Enable TS strict mode by default (#3899)

Fixes #3324 

Co-authored-by: Kitson Kelly <me@kitsonkelly.com>

cli/compilers/ts.rs

@@ -714,7 +714,7 @@ mod tests {
       .unwrap()
       .code
       .as_bytes()
-      .starts_with(b"console.log(\"Hello World\");"));
+      .starts_with(b"\"use strict\";\nconsole.log(\"Hello World\");"));
   }
 
   #[tokio::test]

cli/compilers/wasm_wrap.js

@@ -1,3 +1,4 @@
+// @ts-nocheck
 const importObject = Object.create(null);
 //IMPORTS
 

cli/js/body_test.ts

@@ -45,7 +45,7 @@ testPerm({ net: true }, async function bodyMultipartFormData(): Promise<void> {
 
   const formData = await body.formData();
   assert(formData.has("field_1"));
-  assertEquals(formData.get("field_1").toString(), "value_1 \r\n");
+  assertEquals(formData.get("field_1")!.toString(), "value_1 \r\n");
   assert(formData.has("field_2"));
 });
 
@@ -62,7 +62,7 @@ testPerm({ net: true }, async function bodyURLEncodedFormData(): Promise<void> {
 
   const formData = await body.formData();
   assert(formData.has("field_1"));
-  assertEquals(formData.get("field_1").toString(), "Hi");
+  assertEquals(formData.get("field_1")!.toString(), "Hi");
   assert(formData.has("field_2"));
-  assertEquals(formData.get("field_2").toString(), "<Deno>");
+  assertEquals(formData.get("field_2")!.toString(), "<Deno>");
 });

cli/js/buffer_test.ts

@@ -3,7 +3,7 @@
 // This code has been ported almost directly from Go's src/bytes/buffer_test.go
 // Copyright 2009 The Go Authors. All rights reserved. BSD license.
 // https://github.com/golang/go/blob/master/LICENSE
-import { assertEquals, test } from "./test_util.ts";
+import { assert, assertEquals, test } from "./test_util.ts";
 
 const { Buffer, readAll, readAllSync, writeAll, writeAllSync } = Deno;
 type Buffer = Deno.Buffer;
@@ -78,12 +78,16 @@ function repeat(c: string, bytes: number): Uint8Array {
 
 test(function bufferNewBuffer(): void {
   init();
+  assert(testBytes);
+  assert(testString);
   const buf = new Buffer(testBytes.buffer as ArrayBuffer);
   check(buf, testString);
 });
 
 test(async function bufferBasicOperations(): Promise<void> {
   init();
+  assert(testBytes);
+  assert(testString);
   const buf = new Buffer();
   for (let i = 0; i < 5; i++) {
     check(buf, "");
@@ -134,8 +138,8 @@ test(async function bufferLargeByteWrites(): Promise<void> {
   const buf = new Buffer();
   const limit = 9;
   for (let i = 3; i < limit; i += 3) {
-    const s = await fillBytes(buf, "", 5, testBytes);
+    const s = await fillBytes(buf, "", 5, testBytes!);
-    await empty(buf, s, new Uint8Array(Math.floor(testString.length / i)));
+    await empty(buf, s, new Uint8Array(Math.floor(testString!.length / i)));
   }
   check(buf, "");
 });
@@ -161,6 +165,8 @@ test(async function bufferTooLargeByteWrites(): Promise<void> {
 
 test(async function bufferLargeByteReads(): Promise<void> {
   init();
+  assert(testBytes);
+  assert(testString);
   const buf = new Buffer();
   for (let i = 3; i < 30; i += 3) {
     const n = Math.floor(testBytes.byteLength / i);
@@ -177,6 +183,8 @@ test(function bufferCapWithPreallocatedSlice(): void {
 
 test(async function bufferReadFrom(): Promise<void> {
   init();
+  assert(testBytes);
+  assert(testString);
   const buf = new Buffer();
   for (let i = 3; i < 30; i += 3) {
     const s = await fillBytes(
@@ -194,6 +202,8 @@ test(async function bufferReadFrom(): Promise<void> {
 
 test(async function bufferReadFromSync(): Promise<void> {
   init();
+  assert(testBytes);
+  assert(testString);
   const buf = new Buffer();
   for (let i = 3; i < 30; i += 3) {
     const s = await fillBytes(
@@ -236,6 +246,7 @@ test(async function bufferTestGrow(): Promise<void> {
 
 test(async function testReadAll(): Promise<void> {
   init();
+  assert(testBytes);
   const reader = new Buffer(testBytes.buffer as ArrayBuffer);
   const actualBytes = await readAll(reader);
   assertEquals(testBytes.byteLength, actualBytes.byteLength);
@@ -246,6 +257,7 @@ test(async function testReadAll(): Promise<void> {
 
 test(function testReadAllSync(): void {
   init();
+  assert(testBytes);
   const reader = new Buffer(testBytes.buffer as ArrayBuffer);
   const actualBytes = readAllSync(reader);
   assertEquals(testBytes.byteLength, actualBytes.byteLength);
@@ -256,6 +268,7 @@ test(function testReadAllSync(): void {
 
 test(async function testWriteAll(): Promise<void> {
   init();
+  assert(testBytes);
   const writer = new Buffer();
   await writeAll(writer, testBytes);
   const actualBytes = writer.bytes();
@@ -267,6 +280,7 @@ test(async function testWriteAll(): Promise<void> {
 
 test(function testWriteAllSync(): void {
   init();
+  assert(testBytes);
   const writer = new Buffer();
   writeAllSync(writer, testBytes);
   const actualBytes = writer.bytes();

cli/js/chmod_test.ts

@@ -1,5 +1,5 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
-import { testPerm, assertEquals } from "./test_util.ts";
+import { testPerm, assert, assertEquals } from "./test_util.ts";
 
 const isNotWindows = Deno.build.os !== "win";
 
@@ -16,6 +16,7 @@ testPerm({ read: true, write: true }, function chmodSyncSuccess(): void {
   // Check success when not on windows
   if (isNotWindows) {
     const fileInfo = Deno.statSync(filename);
+    assert(fileInfo.mode);
     assertEquals(fileInfo.mode & 0o777, 0o777);
   }
 });
@@ -35,14 +36,17 @@ if (isNotWindows) {
       Deno.symlinkSync(filename, symlinkName);
 
       let symlinkInfo = Deno.lstatSync(symlinkName);
+      assert(symlinkInfo.mode);
       const symlinkMode = symlinkInfo.mode & 0o777; // platform dependent
 
       Deno.chmodSync(symlinkName, 0o777);
 
       // Change actual file mode, not symlink
       const fileInfo = Deno.statSync(filename);
+      assert(fileInfo.mode);
       assertEquals(fileInfo.mode & 0o777, 0o777);
       symlinkInfo = Deno.lstatSync(symlinkName);
+      assert(symlinkInfo.mode);
       assertEquals(symlinkInfo.mode & 0o777, symlinkMode);
     }
   );
@@ -86,6 +90,7 @@ testPerm({ read: true, write: true }, async function chmodSuccess(): Promise<
   // Check success when not on windows
   if (isNotWindows) {
     const fileInfo = Deno.statSync(filename);
+    assert(fileInfo.mode);
     assertEquals(fileInfo.mode & 0o777, 0o777);
   }
 });
@@ -105,14 +110,17 @@ if (isNotWindows) {
       Deno.symlinkSync(filename, symlinkName);
 
       let symlinkInfo = Deno.lstatSync(symlinkName);
+      assert(symlinkInfo.mode);
       const symlinkMode = symlinkInfo.mode & 0o777; // platform dependent
 
       await Deno.chmod(symlinkName, 0o777);
 
       // Just change actual file mode, not symlink
       const fileInfo = Deno.statSync(filename);
+      assert(fileInfo.mode);
       assertEquals(fileInfo.mode & 0o777, 0o777);
       symlinkInfo = Deno.lstatSync(symlinkName);
+      assert(symlinkInfo.mode);
       assertEquals(symlinkInfo.mode & 0o777, symlinkMode);
     }
   );

cli/js/compiler_host.ts

@@ -49,8 +49,7 @@ export const defaultBundlerOptions: ts.CompilerOptions = {
 export const defaultCompileOptions: ts.CompilerOptions = {
   allowJs: true,
   allowNonTsExtensions: true,
-  // TODO(#3324) Enable strict mode for user code.
+  strict: true,
-  // strict: true,
   checkJs: false,
   esModuleInterop: true,
   module: ts.ModuleKind.ESNext,

cli/js/console_test.ts

@@ -14,8 +14,8 @@ const customInspect = Deno.symbols.customInspect;
 const {
   Console,
   stringifyArgs
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  // @ts-ignore TypeScript (as of 3.7) does not support indexing namespaces by symbol
-} = Deno[Deno.symbols.internal] as any;
+} = Deno[Deno.symbols.internal];
 
 function stringify(...args: unknown[]): string {
   return stringifyArgs(args).replace(/\n$/, "");
@@ -306,6 +306,7 @@ test(function consoleTestCallToStringOnLabel(): void {
   for (const method of methods) {
     let hasCalled = false;
 
+    // @ts-ignore
     console[method]({
       toString(): void {
         hasCalled = true;
@@ -451,6 +452,7 @@ test(function consoleGroup(): void {
 // console.group with console.warn test
 test(function consoleGroupWarn(): void {
   mockConsole((console, _out, _err, both): void => {
+    assert(both);
     console.warn("1");
     console.group();
     console.warn("2");
@@ -694,6 +696,7 @@ test(function consoleDirXml(): void {
 test(function consoleTrace(): void {
   mockConsole((console, _out, err): void => {
     console.trace("%s", "custom message");
+    assert(err);
     assert(err.toString().includes("Trace: custom message"));
   });
 });

cli/js/error_stack_test.ts

@@ -1,8 +1,8 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 import { test, assert } from "./test_util.ts";
 
-// eslint-disable-next-line @typescript-eslint/no-explicit-any
+// @ts-ignore TypeScript (as of 3.7) does not support indexing namespaces by symbol
-const { setPrepareStackTrace } = Deno[Deno.symbols.internal] as any;
+const { setPrepareStackTrace } = Deno[Deno.symbols.internal];
 
 interface CallSite {
   getThis(): unknown;

cli/js/event_target_test.ts

@@ -4,8 +4,11 @@ import { test, assertEquals } from "./test_util.ts";
 test(function addEventListenerTest(): void {
   const document = new EventTarget();
 
+  // @ts-ignore tests ignoring the type system for resilience
   assertEquals(document.addEventListener("x", null, false), undefined);
+  // @ts-ignore
   assertEquals(document.addEventListener("x", null, true), undefined);
+  // @ts-ignore
   assertEquals(document.addEventListener("x", null), undefined);
 });
 
@@ -14,7 +17,7 @@ test(function constructedEventTargetCanBeUsedAsExpected(): void {
   const event = new Event("foo", { bubbles: true, cancelable: false });
   let callCount = 0;
 
-  const listener = (e): void => {
+  const listener = (e: Event): void => {
     assertEquals(e, event);
     ++callCount;
   };
@@ -34,11 +37,19 @@ test(function constructedEventTargetCanBeUsedAsExpected(): void {
 
 test(function anEventTargetCanBeSubclassed(): void {
   class NicerEventTarget extends EventTarget {
-    on(type, callback?, options?): void {
+    on(
+      type: string,
+      callback: (e: Event) => void | null,
+      options?: __domTypes.AddEventListenerOptions
+    ): void {
       this.addEventListener(type, callback, options);
     }
 
-    off(type, callback?, options?): void {
+    off(
+      type: string,
+      callback: (e: Event) => void | null,
+      options?: __domTypes.EventListenerOptions
+    ): void {
       this.removeEventListener(type, callback, options);
     }
   }
@@ -60,8 +71,11 @@ test(function anEventTargetCanBeSubclassed(): void {
 
 test(function removingNullEventListenerShouldSucceed(): void {
   const document = new EventTarget();
+  // @ts-ignore
   assertEquals(document.removeEventListener("x", null, false), undefined);
+  // @ts-ignore
   assertEquals(document.removeEventListener("x", null, true), undefined);
+  // @ts-ignore
   assertEquals(document.removeEventListener("x", null), undefined);
 });
 
@@ -70,7 +84,7 @@ test(function constructedEventTargetUseObjectPrototype(): void {
   const event = new Event("toString", { bubbles: true, cancelable: false });
   let callCount = 0;
 
-  const listener = (e): void => {
+  const listener = (e: Event): void => {
     assertEquals(e, event);
     ++callCount;
   };

cli/js/event_test.ts

@@ -1,5 +1,5 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
-import { test, assertEquals, assertNotEquals } from "./test_util.ts";
+import { test, assertEquals, assert } from "./test_util.ts";
 
 test(function eventInitializedWithType(): void {
   const type = "click";
@@ -70,7 +70,8 @@ test(function eventPreventDefaultSuccess(): void {
 });
 
 test(function eventInitializedWithNonStringType(): void {
-  const type = undefined;
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  const type: any = undefined;
   const event = new Event(type);
 
   assertEquals(event.isTrusted, false);
@@ -84,12 +85,12 @@ test(function eventInitializedWithNonStringType(): void {
 // ref https://github.com/web-platform-tests/wpt/blob/master/dom/events/Event-isTrusted.any.js
 test(function eventIsTrusted(): void {
   const desc1 = Object.getOwnPropertyDescriptor(new Event("x"), "isTrusted");
-  assertNotEquals(desc1, undefined);
+  assert(desc1);
   assertEquals(typeof desc1.get, "function");
 
   const desc2 = Object.getOwnPropertyDescriptor(new Event("x"), "isTrusted");
-  assertNotEquals(desc2, undefined);
+  assert(desc2);
-  assertEquals(typeof desc2.get, "function");
+  assertEquals(typeof desc2!.get, "function");
 
-  assertEquals(desc1.get, desc2.get);
+  assertEquals(desc1!.get, desc2!.get);
 });

cli/js/fetch_test.ts

@@ -54,7 +54,7 @@ testPerm({ net: true }, async function fetchHeaders(): Promise<void> {
   const response = await fetch("http://localhost:4545/cli/tests/fixture.json");
   const headers = response.headers;
   assertEquals(headers.get("Content-Type"), "application/json");
-  assert(headers.get("Server").startsWith("SimpleHTTP"));
+  assert(headers.get("Server")!.startsWith("SimpleHTTP"));
 });
 
 testPerm({ net: true }, async function fetchBlob(): Promise<void> {
@@ -93,10 +93,10 @@ testPerm({ net: true }, async function responseClone(): Promise<void> {
   assert(response !== response1);
   assertEquals(response.status, response1.status);
   assertEquals(response.statusText, response1.statusText);
-  const ab = await response.arrayBuffer();
+  const u8a = new Uint8Array(await response.arrayBuffer());
-  const ab1 = await response1.arrayBuffer();
+  const u8a1 = new Uint8Array(await response1.arrayBuffer());
-  for (let i = 0; i < ab.byteLength; i++) {
+  for (let i = 0; i < u8a.byteLength; i++) {
-    assertEquals(ab[i], ab1[i]);
+    assertEquals(u8a[i], u8a1[i]);
   }
 });
 
@@ -119,7 +119,7 @@ testPerm({ net: true }, async function fetchMultipartFormDataSuccess(): Promise<
   );
   const formData = await response.formData();
   assert(formData.has("field_1"));
-  assertEquals(formData.get("field_1").toString(), "value_1 \r\n");
+  assertEquals(formData.get("field_1")!.toString(), "value_1 \r\n");
   assert(formData.has("field_2"));
   /* TODO(ry) Re-enable this test once we bring back the global File type.
   const file = formData.get("field_2") as File;
@@ -136,9 +136,9 @@ testPerm(
     );
     const formData = await response.formData();
     assert(formData.has("field_1"));
-    assertEquals(formData.get("field_1").toString(), "Hi");
+    assertEquals(formData.get("field_1")!.toString(), "Hi");
     assert(formData.has("field_2"));
-    assertEquals(formData.get("field_2").toString(), "<Deno>");
+    assertEquals(formData.get("field_2")!.toString(), "<Deno>");
   }
 );
 
@@ -179,7 +179,7 @@ testPerm({ net: true }, async function fetchInitStringBody(): Promise<void> {
   });
   const text = await response.text();
   assertEquals(text, data);
-  assert(response.headers.get("content-type").startsWith("text/plain"));
+  assert(response.headers.get("content-type")!.startsWith("text/plain"));
 });
 
 testPerm({ net: true }, async function fetchRequestInitStringBody(): Promise<
@@ -220,7 +220,7 @@ testPerm({ net: true }, async function fetchInitURLSearchParamsBody(): Promise<
   assertEquals(text, data);
   assert(
     response.headers
-      .get("content-type")
+      .get("content-type")!
       .startsWith("application/x-www-form-urlencoded")
   );
 });
@@ -236,7 +236,7 @@ testPerm({ net: true }, async function fetchInitBlobBody(): Promise<void> {
   });
   const text = await response.text();
   assertEquals(text, data);
-  assert(response.headers.get("content-type").startsWith("text/javascript"));
+  assert(response.headers.get("content-type")!.startsWith("text/javascript"));
 });
 
 testPerm({ net: true }, async function fetchUserAgent(): Promise<void> {

cli/js/file_test.ts

@@ -1,7 +1,8 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 import { test, assert, assertEquals } from "./test_util.ts";
 
-function testFirstArgument(arg1, expectedSize): void {
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+function testFirstArgument(arg1: any[], expectedSize: number): void {
   const file = new File(arg1, "name");
   assert(file instanceof File);
   assertEquals(file.name, "name");
@@ -76,7 +77,8 @@ test(function fileObjectInFileBits(): void {
   testFirstArgument([{}], 15);
 });
 
-function testSecondArgument(arg2, expectedFileName): void {
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+function testSecondArgument(arg2: any, expectedFileName: string): void {
   const file = new File(["bits"], arg2);
   assert(file instanceof File);
   assertEquals(file.name, expectedFileName);

cli/js/files_test.ts

@@ -157,6 +157,7 @@ testPerm({ write: true }, async function writeNullBufferFailure(): Promise<
   // writing null should throw an error
   let err;
   try {
+    // @ts-ignore
     await file.write(null);
   } catch (e) {
     err = e;
@@ -182,6 +183,7 @@ testPerm(
     // reading file into null buffer should throw an error
     let err;
     try {
+      // @ts-ignore
       await file.read(null);
     } catch (e) {
       err = e;

cli/js/form_data_test.ts

@@ -36,7 +36,9 @@ test(function formDataParamsGetSuccess(): void {
   formData.append("a", "true");
   formData.append("b", "false");
   formData.append("a", "null");
+  // @ts-ignore
   formData.append("d", undefined);
+  // @ts-ignore
   formData.append("e", null);
   assertEquals(formData.get("a"), "true");
   assertEquals(formData.get("b"), "false");
@@ -63,8 +65,10 @@ test(function formDataParamsSetSuccess(): void {
   assertEquals(formData.getAll("b"), ["false"]);
   formData.set("a", "false");
   assertEquals(formData.getAll("a"), ["false"]);
+  // @ts-ignore
   formData.set("d", undefined);
   assertEquals(formData.get("d"), "undefined");
+  // @ts-ignore
   formData.set("e", null);
   assertEquals(formData.get("e"), "null");
 });
@@ -101,15 +105,22 @@ test(function formDataParamsForEachSuccess(): void {
 });
 
 test(function formDataParamsArgumentsCheck(): void {
-  const methodRequireOneParam = ["delete", "getAll", "get", "has", "forEach"];
+  const methodRequireOneParam = [
+    "delete",
+    "getAll",
+    "get",
+    "has",
+    "forEach"
+  ] as const;
 
-  const methodRequireTwoParams = ["append", "set"];
+  const methodRequireTwoParams = ["append", "set"] as const;
 
   methodRequireOneParam.forEach((method): void => {
     const formData = new FormData();
     let hasThrown = 0;
     let errMsg = "";
     try {
+      // @ts-ignore
       formData[method]();
       hasThrown = 1;
     } catch (err) {
@@ -133,6 +144,7 @@ test(function formDataParamsArgumentsCheck(): void {
     let errMsg = "";
 
     try {
+      // @ts-ignore
       formData[method]();
       hasThrown = 1;
     } catch (err) {
@@ -152,6 +164,7 @@ test(function formDataParamsArgumentsCheck(): void {
     hasThrown = 0;
     errMsg = "";
     try {
+      // @ts-ignore
       formData[method]("foo");
       hasThrown = 1;
     } catch (err) {

cli/js/headers_test.ts

@@ -2,8 +2,8 @@
 import { test, assert, assertEquals } from "./test_util.ts";
 const {
   stringifyArgs
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  // @ts-ignore TypeScript (as of 3.7) does not support indexing namespaces by symbol
-} = Deno[Deno.symbols.internal] as any;
+} = Deno[Deno.symbols.internal];
 
 // Logic heavily copied from web-platform-tests, make
 // sure pass mostly header basic test
@@ -13,6 +13,7 @@ test(function newHeaderTest(): void {
   new Headers(undefined);
   new Headers({});
   try {
+    // @ts-ignore
     new Headers(null);
   } catch (e) {
     assertEquals(
@@ -22,14 +23,16 @@ test(function newHeaderTest(): void {
   }
 });
 
-const headerDict = {
+const headerDict: Record<string, string> = {
   name1: "value1",
   name2: "value2",
   name3: "value3",
+  // @ts-ignore
   name4: undefined,
   "Content-Type": "value4"
 };
-const headerSeq = [];
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+const headerSeq: any[] = [];
 for (const name in headerDict) {
   headerSeq.push([name, headerDict[name]]);
 }
@@ -133,7 +136,7 @@ test(function headerValuesSuccess(): void {
   }
 });
 
-const headerEntriesDict = {
+const headerEntriesDict: Record<string, string> = {
   name1: "value1",
   Name2: "value2",
   name: "value3",
@@ -261,6 +264,7 @@ test(function headerParamsArgumentsCheck(): void {
     let hasThrown = 0;
     let errMsg = "";
     try {
+      // @ts-ignore
       headers[method]();
       hasThrown = 1;
     } catch (err) {
@@ -284,6 +288,7 @@ test(function headerParamsArgumentsCheck(): void {
     let errMsg = "";
 
     try {
+      // @ts-ignore
       headers[method]();
       hasThrown = 1;
     } catch (err) {
@@ -303,6 +308,7 @@ test(function headerParamsArgumentsCheck(): void {
     hasThrown = 0;
     errMsg = "";
     try {
+      // @ts-ignore
       headers[method]("foo");
       hasThrown = 1;
     } catch (err) {

cli/js/internals_test.ts

@@ -4,7 +4,7 @@ import { test, assert } from "./test_util.ts";
 test(function internalsExists(): void {
   const {
     stringifyArgs
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    // @ts-ignore TypeScript (as of 3.7) does not support indexing namespaces by symbol
-  } = Deno[Deno.symbols.internal] as any;
+  } = Deno[Deno.symbols.internal];
   assert(!!stringifyArgs);
 });

cli/js/mixins/dom_iterable_test.ts

@@ -20,11 +20,8 @@ function setup() {
     Base,
     // This is using an internal API we don't want published as types, so having
     // to cast to any to "trick" TypeScript
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    // @ts-ignore TypeScript (as of 3.7) does not support indexing namespaces by symbol
-    DomIterable: (Deno[Deno.symbols.internal] as any).DomIterableMixin(
+    DomIterable: Deno[Deno.symbols.internal].DomIterableMixin(Base, dataSymbol)
-      Base,
-      dataSymbol
-    )
   };
 }
 
@@ -52,7 +49,12 @@ test(function testDomIterable(): void {
 
   result = [];
   const scope = {};
-  function callback(value, key, parent): void {
+  function callback(
+    this: typeof scope,
+    value: number,
+    key: string,
+    parent: typeof domIterable
+  ): void {
     assertEquals(parent, domIterable);
     assert(key != null);
     assert(value != null);
@@ -72,7 +74,7 @@ test(function testDomIterableScope(): void {
 
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   function checkScope(thisArg: any, expected: any): void {
-    function callback(): void {
+    function callback(this: typeof thisArg): void {
       assertEquals(this, expected);
     }
     domIterable.forEach(callback, thisArg);

cli/js/net_test.ts

@@ -27,7 +27,7 @@ testPerm({ net: true }, async function netCloseWhileAccept(): Promise<void> {
 testPerm({ net: true }, async function netConcurrentAccept(): Promise<void> {
   const listener = Deno.listen({ port: 4502 });
   let acceptErrCount = 0;
-  const checkErr = (e): void => {
+  const checkErr = (e: Deno.DenoError<Deno.ErrorKind>): void => {
     assertEquals(e.kind, Deno.ErrorKind.Other);
     if (e.message === "Listener has been closed") {
       assertEquals(acceptErrCount, 1);

cli/js/os_test.ts

@@ -56,7 +56,10 @@ if (Deno.build.os === "win") {
     // specified in `inputEnv`. The subprocess reads the environment variables
     // which are in the keys of `expectedEnv` and writes them to stdout as JSON.
     // It is then verified that these match with the values of `expectedEnv`.
-    const checkChildEnv = async (inputEnv, expectedEnv): Promise<void> => {
+    const checkChildEnv = async (
+      inputEnv: Record<string, string>,
+      expectedEnv: Record<string, string>
+    ): Promise<void> => {
       const src = `
         console.log(
           ${JSON.stringify(Object.keys(expectedEnv))}.map(k => Deno.env(k))
@@ -249,6 +252,7 @@ testPerm({ env: true }, function getDir(): void {
       if (Deno.build.os !== r.os) continue;
       if (r.shouldHaveValue) {
         const d = Deno.dir(s.kind);
+        assert(d);
         assert(d.length > 0);
       }
     }

cli/js/process_test.ts

@@ -130,6 +130,7 @@ testPerm({ run: true }, async function runStdinPiped(): Promise<void> {
     args: ["python", "-c", "import sys; assert 'hello' == sys.stdin.read();"],
     stdin: "piped"
   });
+  assert(p.stdin);
   assert(!p.stdout);
   assert(!p.stderr);
 
@@ -137,7 +138,7 @@ testPerm({ run: true }, async function runStdinPiped(): Promise<void> {
   const n = await p.stdin.write(msg);
   assertEquals(n, msg.byteLength);
 
-  p.stdin.close();
+  p.stdin!.close();
 
   const status = await p.status();
   assertEquals(status.success, true);
@@ -155,16 +156,16 @@ testPerm({ run: true }, async function runStdoutPiped(): Promise<void> {
   assert(!p.stderr);
 
   const data = new Uint8Array(10);
-  let r = await p.stdout.read(data);
+  let r = await p.stdout!.read(data);
   if (r === Deno.EOF) {
     throw new Error("p.stdout.read(...) should not be EOF");
   }
   assertEquals(r, 5);
   const s = new TextDecoder().decode(data.subarray(0, r));
   assertEquals(s, "hello");
-  r = await p.stdout.read(data);
+  r = await p.stdout!.read(data);
   assertEquals(r, Deno.EOF);
-  p.stdout.close();
+  p.stdout!.close();
 
   const status = await p.status();
   assertEquals(status.success, true);
@@ -182,16 +183,16 @@ testPerm({ run: true }, async function runStderrPiped(): Promise<void> {
   assert(!p.stdout);
 
   const data = new Uint8Array(10);
-  let r = await p.stderr.read(data);
+  let r = await p.stderr!.read(data);
   if (r === Deno.EOF) {
     throw new Error("p.stderr.read should not return EOF here");
   }
   assertEquals(r, 5);
   const s = new TextDecoder().decode(data.subarray(0, r));
   assertEquals(s, "hello");
-  r = await p.stderr.read(data);
+  r = await p.stderr!.read(data);
   assertEquals(r, Deno.EOF);
-  p.stderr.close();
+  p.stderr!.close();
 
   const status = await p.status();
   assertEquals(status.success, true);
@@ -307,7 +308,7 @@ testPerm({ run: true }, async function runClose(): Promise<void> {
   p.close();
 
   const data = new Uint8Array(10);
-  const r = await p.stderr.read(data);
+  const r = await p.stderr!.read(data);
   assertEquals(r, Deno.EOF);
 });
 

cli/js/resources_test.ts

@@ -39,8 +39,8 @@ testPerm({ read: true }, async function resourcesFile(): Promise<void> {
     Object.keys(resourcesAfter).length,
     Object.keys(resourcesBefore).length + 1
   );
-  const newRid = Object.keys(resourcesAfter).find((rid): boolean => {
+  const newRid = +Object.keys(resourcesAfter).find((rid): boolean => {
     return !resourcesBefore.hasOwnProperty(rid);
-  });
+  })!;
   assertEquals(resourcesAfter[newRid], "fsFile");
 });

cli/js/signal_test.ts

@@ -8,7 +8,7 @@ import {
 } from "./test_util.ts";
 
 function defer(n: number): Promise<void> {
-  return new Promise((resolve, _) => {
+  return new Promise((resolve: () => void, _) => {
     setTimeout(resolve, n);
   });
 }

cli/js/stat_test.ts

@@ -210,7 +210,7 @@ if (isWindows) {
       const s = Deno.statSync(filename);
       assert(s.dev !== null);
       assert(s.ino !== null);
-      assertEquals(s.mode & 0o666, 0o666);
+      assertEquals(s.mode! & 0o666, 0o666);
       assertEquals(s.nlink, 2);
       assert(s.uid !== null);
       assert(s.gid !== null);

cli/js/test_util.ts

@@ -62,7 +62,10 @@ function permissionsMatch(
   requiredPerms: Permissions
 ): boolean {
   for (const permName in processPerms) {
-    if (processPerms[permName] !== requiredPerms[permName]) {
+    if (
+      processPerms[permName as keyof Permissions] !==
+      requiredPerms[permName as keyof Permissions]
+    ) {
       return false;
     }
   }
@@ -302,7 +305,7 @@ testPerm(
   async function assertAllUnitTestFilesImported(): Promise<void> {
     const directoryTestFiles = Deno.readDirSync("./cli/js")
       .map(k => k.name)
-      .filter(file => file.endsWith("_test.ts"));
+      .filter(file => file!.endsWith("_test.ts"));
     const unitTestsFile: Uint8Array = Deno.readFileSync(
       "./cli/js/unit_tests.ts"
     );
@@ -311,11 +314,11 @@ testPerm(
       .split("\n")
       .filter(line => line.startsWith("import") && line.includes("_test.ts"));
     const importedTestFiles = importLines.map(
-      relativeFilePath => relativeFilePath.match(/\/([^\/]+)";/)[1]
+      relativeFilePath => relativeFilePath.match(/\/([^\/]+)";/)![1]
     );
 
     directoryTestFiles.forEach(dirFile => {
-      if (!importedTestFiles.includes(dirFile)) {
+      if (!importedTestFiles.includes(dirFile!)) {
         throw new Error(
           "cil/js/unit_tests.ts is missing import of test file: cli/js/" +
             dirFile

cli/js/timers_test.ts

@@ -7,21 +7,22 @@ function deferred(): {
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   reject: (reason?: any) => void;
 } {
-  let resolve;
+  let resolve: (value?: {} | PromiseLike<{}>) => void;
-  let reject;
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  const promise = new Promise((res, rej): void => {
+  let reject: ((reason?: any) => void) | undefined = undefined;
+  const promise = new Promise<{}>((res, rej): void => {
     resolve = res;
     reject = rej;
   });
   return {
     promise,
-    resolve,
+    resolve: resolve!,
-    reject
+    reject: reject!
   };
 }
 
-async function waitForMs(ms): Promise<number> {
+async function waitForMs(ms: number): Promise<number> {
-  return new Promise((resolve): number => setTimeout(resolve, ms));
+  return new Promise((resolve: () => void): number => setTimeout(resolve, ms));
 }
 
 test(async function timeoutSuccess(): Promise<void> {
@@ -133,7 +134,7 @@ test(async function intervalCancelSuccess(): Promise<void> {
 });
 
 test(async function intervalOrdering(): Promise<void> {
-  const timers = [];
+  const timers: number[] = [];
   let timeouts = 0;
   function onTimeout(): void {
     ++timeouts;

cli/js/tls_test.ts

@@ -195,7 +195,7 @@ testPerm({ read: true, net: true }, async function dialAndListenTLS(): Promise<
   assertEquals(ok, "OK");
   const headers = await tpr.readMIMEHeader();
   assert(headers !== Deno.EOF);
-  const contentLength = parseInt(headers.get("content-length"));
+  const contentLength = parseInt(headers.get("content-length")!);
   const bodyBuf = new Uint8Array(contentLength);
   await r.readFull(bodyBuf);
   assertEquals(decoder.decode(bodyBuf), "Hello World\n");

cli/js/url_search_params_test.ts

@@ -177,6 +177,7 @@ test(function urlSearchParamsAppendArgumentsCheck(): void {
       const searchParams = new URLSearchParams();
       let hasThrown = 0;
       try {
+        // @ts-ignore
         searchParams[method]();
         hasThrown = 1;
       } catch (err) {
@@ -193,6 +194,7 @@ test(function urlSearchParamsAppendArgumentsCheck(): void {
     const searchParams = new URLSearchParams();
     let hasThrown = 0;
     try {
+      // @ts-ignore
       searchParams[method]("foo");
       hasThrown = 1;
     } catch (err) {
@@ -232,6 +234,7 @@ test(function urlSearchParamsCustomSymbolIterator(): void {
 
 test(function urlSearchParamsCustomSymbolIteratorWithNonStringParams(): void {
   const params = {};
+  // @ts-ignore
   params[Symbol.iterator] = function*(): IterableIterator<[number, number]> {
     yield [1, 2];
   };

cli/js/utime_test.ts

@@ -3,7 +3,9 @@ import { testPerm, assert, assertEquals } from "./test_util.ts";
 
 // Allow 10 second difference.
 // Note this might not be enough for FAT (but we are not testing on such fs).
-function assertFuzzyTimestampEquals(t1: number, t2: number): void {
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+function assertFuzzyTimestampEquals(t1: any, t2: number): void {
+  assert(typeof t1 === "number");
   assert(Math.abs(t1 - t2) < 10);
 }
 

cli/js/write_file_test.ts

@@ -50,9 +50,9 @@ testPerm({ read: true, write: true }, function writeFileSyncUpdatePerm(): void {
     const data = enc.encode("Hello");
     const filename = Deno.makeTempDirSync() + "/test.txt";
     Deno.writeFileSync(filename, data, { perm: 0o755 });
-    assertEquals(Deno.statSync(filename).mode & 0o777, 0o755);
+    assertEquals(Deno.statSync(filename).mode! & 0o777, 0o755);
     Deno.writeFileSync(filename, data, { perm: 0o666 });
-    assertEquals(Deno.statSync(filename).mode & 0o777, 0o666);
+    assertEquals(Deno.statSync(filename).mode! & 0o777, 0o666);
   }
 });
 
@@ -161,9 +161,9 @@ testPerm(
       const data = enc.encode("Hello");
       const filename = Deno.makeTempDirSync() + "/test.txt";
       await Deno.writeFile(filename, data, { perm: 0o755 });
-      assertEquals(Deno.statSync(filename).mode & 0o777, 0o755);
+      assertEquals(Deno.statSync(filename).mode! & 0o777, 0o755);
       await Deno.writeFile(filename, data, { perm: 0o666 });
-      assertEquals(Deno.statSync(filename).mode & 0o777, 0o666);
+      assertEquals(Deno.statSync(filename).mode! & 0o777, 0o666);
     }
   }
 );

cli/tests/046_jsx_test.tsx

@@ -1,3 +1,8 @@
+declare namespace JSX {
+  interface IntrinsicElements {
+    [elemName: string]: any;
+  }
+}
 const React = {
   createElement(factory: any, props: any, ...children: any[]) {
     return {factory, props, children}

cli/tests/048_media_types_jsx.ts

@@ -10,6 +10,16 @@ import { loaded as loadedJsx2 } from "http://localhost:4545/cli/tests/subdir/mt_
 import { loaded as loadedJsx3 } from "http://localhost:4545/cli/tests/subdir/mt_text_ecmascript_jsx.j3.jsx";
 import { loaded as loadedJsx4 } from "http://localhost:4545/cli/tests/subdir/mt_application_x_javascript_jsx.j4.jsx";
 
+declare global {
+  // eslint-disable-next-line @typescript-eslint/no-namespace
+  namespace JSX {
+    interface IntrinsicElements {
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      [elemName: string]: any;
+    }
+  }
+}
+
 console.log(
   "success",
   loadedTsx1,

std/encoding/base32_test.ts

@@ -6,7 +6,7 @@ import { encode, decode } from "./base32.ts";
 
 // Lifted from https://stackoverflow.com/questions/38987784
 const fromHexString = (hexString: string): Uint8Array =>
-  new Uint8Array(hexString.match(/.{1,2}/g).map(byte => parseInt(byte, 16)));
+  new Uint8Array(hexString.match(/.{1,2}/g)!.map(byte => parseInt(byte, 16)));
 const toHexString = (bytes: Uint8Array): string =>
   bytes.reduce((str, byte) => str + byte.toString(16).padStart(2, "0"), "");
 

std/encoding/csv.ts

@@ -46,7 +46,7 @@ function chkOptions(opt: ReadOptions): void {
   }
   if (
     INVALID_RUNE.includes(opt.comma) ||
-    INVALID_RUNE.includes(opt.comment) ||
+    (typeof opt.comment === "string" && INVALID_RUNE.includes(opt.comment)) ||
     opt.comma === opt.comment
   ) {
     throw new Error("Invalid Delimiter");
@@ -122,7 +122,7 @@ export async function readMatrix(
   }
 ): Promise<string[][]> {
   const result: string[][] = [];
-  let _nbFields: number;
+  let _nbFields: number | undefined;
   let lineResult: string[];
   let first = true;
   let lineIndex = 0;
@@ -253,8 +253,10 @@ export async function parse(
     });
   }
   if (opt.parse) {
-    assert(opt.parse != null, "opt.parse must be set");
+    return r.map((e: string[]): unknown => {
-    return r.map((e: string[]): unknown => opt.parse(e));
+      assert(opt.parse, "opt.parse must be set");
+      return opt.parse(e);
+    });
   }
   return r;
 }

std/encoding/csv_test.ts

@@ -476,26 +476,32 @@ for (const t of testCases) {
       if (t.Error) {
         let err;
         try {
-          actual = await readMatrix(new BufReader(new StringReader(t.Input)), {
+          actual = await readMatrix(
-            comma: comma,
+            new BufReader(new StringReader(t.Input ?? "")),
-            comment: comment,
+            {
-            trimLeadingSpace: trim,
+              comma: comma,
-            fieldsPerRecord: fieldsPerRec,
+              comment: comment,
-            lazyQuotes: lazyquote
+              trimLeadingSpace: trim,
-          });
+              fieldsPerRecord: fieldsPerRec,
+              lazyQuotes: lazyquote
+            }
+          );
         } catch (e) {
           err = e;
         }
         assert(err);
         assertEquals(err.message, t.Error);
       } else {
-        actual = await readMatrix(new BufReader(new StringReader(t.Input)), {
+        actual = await readMatrix(
-          comma: comma,
+          new BufReader(new StringReader(t.Input ?? "")),
-          comment: comment,
+          {
-          trimLeadingSpace: trim,
+            comma: comma,
-          fieldsPerRecord: fieldsPerRec,
+            comment: comment,
-          lazyQuotes: lazyquote
+            trimLeadingSpace: trim,
-        });
+            fieldsPerRecord: fieldsPerRec,
+            lazyQuotes: lazyquote
+          }
+        );
         const expected = t.Output;
         assertEquals(actual, expected);
       }

std/encoding/yaml/loader/loader.ts

@@ -187,7 +187,7 @@ interface DirectiveHandlers {
   [directive: string]: (
     state: LoaderState,
     name: string,
-    ...args: unknown[]
+    ...args: string[]
   ) => void;
 }
 
@@ -362,7 +362,7 @@ function storeMappingPair(
         mergeMappings(state, result, valueNode[index], overridableKeys);
       }
     } else {
-      mergeMappings(state, result, valueNode, overridableKeys);
+      mergeMappings(state, result, valueNode as ArrayObject, overridableKeys);
     }
   } else {
     if (
@@ -1610,7 +1610,7 @@ function readDocument(state: LoaderState): void {
   const documentStart = state.position;
   let position: number,
     directiveName: string,
-    directiveArgs: unknown[],
+    directiveArgs: string[],
     hasDirectives = false,
     ch: number;
 

std/examples/gist.ts

@@ -24,7 +24,7 @@ if (parsedArgs._.length === 0) {
   Deno.exit(1);
 }
 
-const files = {};
+const files: Record<string, { content: string }> = {};
 for (const filename of parsedArgs._) {
   const base = pathBase(filename);
   const content = await Deno.readFile(filename);

std/fs/copy.ts

@@ -85,6 +85,8 @@ async function copyFile(
   await Deno.copyFile(src, dest);
   if (options.preserveTimestamps) {
     const statInfo = await Deno.stat(src);
+    assert(statInfo.accessed != null, `statInfo.accessed is unavailable`);
+    assert(statInfo.modified != null, `statInfo.modified is unavailable`);
     await Deno.utime(dest, statInfo.accessed, statInfo.modified);
   }
 }

std/fs/empty_dir_test.ts

@@ -1,5 +1,6 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 import {
+  assert,
   assertEquals,
   assertStrContains,
   assertThrows,
@@ -225,6 +226,8 @@ Deno.test(async function emptyDirPermission(): Promise<void> {
         args: args
       });
 
+      assert(stdout);
+
       const output = await Deno.readAll(stdout);
 
       assertStrContains(new TextDecoder().decode(output), s.output);

std/fs/exists_test.ts

@@ -131,7 +131,7 @@ Deno.test(async function existsPermission(): Promise<void> {
       args: args
     });
 
-    const output = await Deno.readAll(stdout);
+    const output = await Deno.readAll(stdout!);
 
     assertStrContains(new TextDecoder().decode(output), s.output);
   }

std/fs/walk.ts

@@ -65,9 +65,9 @@ export async function* walk(
     includeFiles = true,
     includeDirs = true,
     followSymlinks = false,
-    exts = null,
+    exts = undefined,
-    match = null,
+    match = undefined,
-    skip = null
+    skip = undefined
   }: WalkOptions = {}
 ): AsyncIterableIterator<WalkInfo> {
   if (maxDepth < 0) {
@@ -76,7 +76,7 @@ export async function* walk(
   if (includeDirs && include(root, exts, match, skip)) {
     yield { filename: root, info: await stat(root) };
   }
-  if (maxDepth < 1 || !include(root, null, null, skip)) {
+  if (maxDepth < 1 || !include(root, undefined, undefined, skip)) {
     return;
   }
   const ls: FileInfo[] = await readDir(root);
@@ -119,9 +119,9 @@ export function* walkSync(
     includeFiles = true,
     includeDirs = true,
     followSymlinks = false,
-    exts = null,
+    exts = undefined,
-    match = null,
+    match = undefined,
-    skip = null
+    skip = undefined
   }: WalkOptions = {}
 ): IterableIterator<WalkInfo> {
   if (maxDepth < 0) {
@@ -130,7 +130,7 @@ export function* walkSync(
   if (includeDirs && include(root, exts, match, skip)) {
     yield { filename: root, info: statSync(root) };
   }
-  if (maxDepth < 1 || !include(root, null, null, skip)) {
+  if (maxDepth < 1 || !include(root, undefined, undefined, skip)) {
     return;
   }
   const ls: FileInfo[] = readDirSync(root);

std/http/cookie.ts

@@ -45,7 +45,7 @@ function toString(cookie: Cookie): string {
   if (cookie.httpOnly) {
     out.push("HttpOnly");
   }
-  if (Number.isInteger(cookie.maxAge)) {
+  if (typeof cookie.maxAge === "number" && Number.isInteger(cookie.maxAge)) {
     assert(cookie.maxAge > 0, "Max-Age must be an integer superior to 0");
     out.push(`Max-Age=${cookie.maxAge}`);
   }

std/http/file_server.ts

@@ -15,6 +15,7 @@ import {
   Response
 } from "./server.ts";
 import { parse } from "../flags/mod.ts";
+import { assert } from "../testing/asserts.ts";
 
 interface EntryInfo {
   mode: string;
@@ -40,10 +41,10 @@ const encoder = new TextEncoder();
 const serverArgs = parse(args) as FileServerArgs;
 
 const CORSEnabled = serverArgs.cors ? true : false;
-const target = posix.resolve(serverArgs._[1] || "");
+const target = posix.resolve(serverArgs._[1] ?? "");
-const addr = `0.0.0.0:${serverArgs.port || serverArgs.p || 4500}`;
+const addr = `0.0.0.0:${serverArgs.port ?? serverArgs.p ?? 4500}`;
 
-if (serverArgs.h || serverArgs.help) {
+if (serverArgs.h ?? serverArgs.help) {
   console.log(`Deno File Server
   Serves a local directory in HTTP.
 
@@ -125,8 +126,8 @@ async function serveDir(
   const listEntry: EntryInfo[] = [];
   const fileInfos = await readDir(dirPath);
   for (const fileInfo of fileInfos) {
-    const filePath = posix.join(dirPath, fileInfo.name);
+    const filePath = posix.join(dirPath, fileInfo.name ?? "");
-    const fileUrl = posix.join(dirUrl, fileInfo.name);
+    const fileUrl = posix.join(dirUrl, fileInfo.name ?? "");
     if (fileInfo.name === "index.html" && fileInfo.isFile()) {
       // in case index.html as dir...
       return await serveFile(req, filePath);
@@ -139,7 +140,7 @@ async function serveDir(
     listEntry.push({
       mode: modeToString(fileInfo.isDirectory(), mode),
       size: fileInfo.isFile() ? fileLenToString(fileInfo.len) : "",
-      name: fileInfo.name,
+      name: fileInfo.name ?? "",
       url: fileUrl
     });
   }
@@ -311,7 +312,7 @@ listenAndServe(
     }
     const fsPath = posix.join(target, normalizedUrl);
 
-    let response: Response;
+    let response: Response | undefined;
     try {
       const info = await stat(fsPath);
       if (info.isDirectory()) {
@@ -324,10 +325,11 @@ listenAndServe(
       response = await serveFallback(req, e);
     } finally {
       if (CORSEnabled) {
+        assert(response);
         setCORS(response);
       }
-      serverLog(req, response);
+      serverLog(req, response!);
-      req.respond(response);
+      req.respond(response!);
     }
   }
 );

std/http/file_server_test.ts

@@ -38,7 +38,7 @@ test(async function serveFile(): Promise<void> {
     assert(res.headers.has("access-control-allow-origin"));
     assert(res.headers.has("access-control-allow-headers"));
     assert(res.headers.has("content-type"));
-    assert(res.headers.get("content-type").includes("charset=utf-8"));
+    assert(res.headers.get("content-type")!.includes("charset=utf-8"));
     const downloadedFile = await res.text();
     const localFile = new TextDecoder().decode(
       await Deno.readFile("README.md")

std/http/server.ts

@@ -436,7 +436,7 @@ export class Server implements AsyncIterable<ServerRequest> {
   ): AsyncIterableIterator<ServerRequest> {
     const bufr = new BufReader(conn);
     const w = new BufWriter(conn);
-    let req: ServerRequest | Deno.EOF;
+    let req: ServerRequest | Deno.EOF | undefined;
     let err: Error | undefined;
 
     while (!this.closing) {

std/http/server_test.ts

@@ -545,7 +545,7 @@ test(async function testReadRequestError(): Promise<void> {
   for (const test of testCases) {
     const reader = new BufReader(new StringReader(test.in));
     let err;
-    let req: ServerRequest | Deno.EOF;
+    let req: ServerRequest | Deno.EOF | undefined;
     try {
       req = await readRequest(mockConn as Deno.Conn, reader);
     } catch (e) {
@@ -559,7 +559,7 @@ test(async function testReadRequestError(): Promise<void> {
       assert(err instanceof (test.err as typeof UnexpectedEOFError));
     } else {
       assert(req instanceof ServerRequest);
-      assert(test.headers != null);
+      assert(test.headers);
       assertEquals(err, undefined);
       assertNotEquals(req, Deno.EOF);
       for (const h of test.headers) {
@@ -719,6 +719,7 @@ if (Deno.build.os !== "win") {
       const serverRoutine = async (): Promise<void> => {
         let reqCount = 0;
         const server = serve(":8124");
+        // @ts-ignore
         const serverRid = server.listener["rid"];
         let connRid = -1;
         for await (const req of server) {

std/io/bufio.ts

@@ -311,7 +311,7 @@ export class BufReader implements Reader {
    */
   async readSlice(delim: number): Promise<Uint8Array | Deno.EOF> {
     let s = 0; // search start index
-    let slice: Uint8Array;
+    let slice: Uint8Array | undefined;
 
     while (true) {
       // Search buffer.

std/manual.md

@@ -1538,7 +1538,7 @@ Build with Cargo:
 cargo build -vv
 
 # Run:
-./target/debug/deno tests/002_hello.ts
+./target/debug/deno cli/tests/002_hello.ts
 ```
 
 #### Testing and Tools

std/node/events.ts

@@ -22,6 +22,7 @@
 // USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 import { validateIntegerRange } from "./util.ts";
+import { assert } from "../testing/asserts.ts";
 
 export interface WrappedFunction extends Function {
   listener: Function;
@@ -163,7 +164,8 @@ export default class EventEmitter {
   private unwrapListeners(arr: Function[]): Function[] {
     const unwrappedListeners: Function[] = new Array(arr.length) as Function[];
     for (let i = 0; i < arr.length; i++) {
-      unwrappedListeners[i] = arr[i]["listener"] || arr[i];
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      unwrappedListeners[i] = (arr[i] as any)["listener"] || arr[i];
     }
     return unwrappedListeners;
   }
@@ -232,10 +234,12 @@ export default class EventEmitter {
     const wrapperContext = {
       eventName: eventName,
       listener: listener,
-      rawListener: wrapper,
+      rawListener: (wrapper as unknown) as WrappedFunction,
       context: this
     };
-    const wrapped = wrapper.bind(wrapperContext);
+    const wrapped = (wrapper.bind(
+      wrapperContext
+    ) as unknown) as WrappedFunction;
     wrapperContext.rawListener = wrapped;
     wrapped.listener = listener;
     return wrapped as WrappedFunction;
@@ -275,7 +279,7 @@ export default class EventEmitter {
       return this;
     }
 
-    if (this._events.has(eventName)) {
+    if (eventName && this._events.has(eventName)) {
       const listeners = (this._events.get(eventName) as Array<
         Function | WrappedFunction
       >).slice(); // Create a copy; We use it AFTER it's deleted.
@@ -299,14 +303,19 @@ export default class EventEmitter {
    */
   public removeListener(eventName: string | symbol, listener: Function): this {
     if (this._events.has(eventName)) {
-      const arr: Array<Function | WrappedFunction> = this._events.get(
+      const arr:
-        eventName
+        | Array<Function | WrappedFunction>
-      );
+        | undefined = this._events.get(eventName);
+
+      assert(arr);
 
       let listenerIndex = -1;
       for (let i = arr.length - 1; i >= 0; i--) {
         // arr[i]["listener"] is the reference to the listener inside a bound 'once' wrapper
-        if (arr[i] == listener || arr[i]["listener"] == listener) {
+        if (
+          arr[i] == listener ||
+          (arr[i] && (arr[i] as WrappedFunction)["listener"] == listener)
+        ) {
           listenerIndex = i;
           break;
         }
@@ -421,8 +430,10 @@ export function on(
 ): AsyncInterable {
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   const unconsumedEventValues: any[] = [];
-  const unconsumedPromises = [];
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  let error = null;
+  const unconsumedPromises: any[] = [];
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  let error: Error | null = null;
   let finished = false;
 
   const iterator = {
@@ -476,7 +487,7 @@ export function on(
     },
 
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    [Symbol.asyncIterator](): AsyncIterable<any> {
+    [Symbol.asyncIterator](): any {
       return this;
     }
   };

std/node/events_test.ts

@@ -17,7 +17,7 @@ test({
   fn() {
     let eventsFired: string[] = [];
     const testEmitter = new EventEmitter();
-    testEmitter.on("newListener", event => {
+    testEmitter.on("newListener", (event: string) => {
       if (event !== "newListener") {
         eventsFired.push("newListener");
       }
@@ -81,20 +81,23 @@ test({
   fn() {
     const testEmitter = new EventEmitter();
     const eventsFired: string[] = [];
-    testEmitter.on("event", oneArg => {
+    testEmitter.on("event", (oneArg: string) => {
       eventsFired.push("event(" + oneArg + ")");
     });
-    testEmitter.on("event", (oneArg, twoArg) => {
+    testEmitter.on("event", (oneArg: string, twoArg: string) => {
       eventsFired.push("event(" + oneArg + ", " + twoArg + ")");
     });
 
     testEmitter.on("non-event", shouldNeverBeEmitted);
 
-    testEmitter.on("event", (oneArg, twoArg, threeArg) => {
+    testEmitter.on(
-      eventsFired.push(
+      "event",
-        "event(" + oneArg + ", " + twoArg + ", " + threeArg + ")"
+      (oneArg: string, twoArg: string, threeArg: string) => {
-      );
+        eventsFired.push(
-    });
+          "event(" + oneArg + ", " + twoArg + ", " + threeArg + ")"
+        );
+      }
+    );
     testEmitter.emit("event", 1, 2, 3);
     assertEquals(eventsFired, ["event(1)", "event(1, 2)", "event(1, 2, 3)"]);
   }

std/node/global.ts

@@ -1 +1,2 @@
-window["global"] = window;
+// @ts-ignore
+globalThis["global"] = globalThis;

std/node/module.ts

@@ -40,7 +40,7 @@ const isWindows = path.isWindows;
 const relativeResolveCache = Object.create(null);
 
 let requireDepth = 0;
-let statCache = null;
+let statCache: Map<string, StatResult> | null = null;
 
 type StatResult = -1 | 0 | 1;
 // Returns 0 if the path refers to
@@ -64,7 +64,11 @@ function stat(filename: string): StatResult {
   }
 }
 
-function updateChildren(parent: Module, child: Module, scan: boolean): void {
+function updateChildren(
+  parent: Module | null,
+  child: Module,
+  scan: boolean
+): void {
   const children = parent && parent.children;
   if (children && !(scan && children.includes(child))) {
     children.push(child);
@@ -75,17 +79,17 @@ class Module {
   id: string;
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   exports: any;
-  parent?: Module;
+  parent: Module | null;
-  filename: string;
+  filename: string | null;
   loaded: boolean;
   children: Module[];
   paths: string[];
   path: string;
-  constructor(id = "", parent?: Module) {
+  constructor(id = "", parent?: Module | null) {
     this.id = id;
     this.exports = {};
-    this.parent = parent;
+    this.parent = parent || null;
-    updateChildren(parent, this, false);
+    updateChildren(parent || null, this, false);
     this.filename = null;
     this.loaded = false;
     this.children = [];
@@ -229,25 +233,25 @@ class Module {
             fakeParent.paths = Module._nodeModulePaths(path);
             const lookupPaths = Module._resolveLookupPaths(request, fakeParent);
 
-            for (let j = 0; j < lookupPaths.length; j++) {
+            for (let j = 0; j < lookupPaths!.length; j++) {
-              if (!paths.includes(lookupPaths[j])) paths.push(lookupPaths[j]);
+              if (!paths.includes(lookupPaths![j])) paths.push(lookupPaths![j]);
             }
           }
         }
       } else if (options.paths === undefined) {
-        paths = Module._resolveLookupPaths(request, parent);
+        paths = Module._resolveLookupPaths(request, parent)!;
       } else {
         throw new Error("options.paths is invalid");
       }
     } else {
-      paths = Module._resolveLookupPaths(request, parent);
+      paths = Module._resolveLookupPaths(request, parent)!;
     }
 
     // Look up the filename first, since that's the cache key.
     const filename = Module._findPath(request, paths, isMain);
     if (!filename) {
       const requireStack = [];
-      for (let cursor = parent; cursor; cursor = cursor.parent) {
+      for (let cursor: Module | null = parent; cursor; cursor = cursor.parent) {
         requireStack.push(cursor.filename || cursor.id);
       }
       let message = `Cannot find module '${request}'`;
@@ -341,7 +345,7 @@ class Module {
   //    object.
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   static _load(request: string, parent: Module, isMain: boolean): any {
-    let relResolveCacheIdentifier;
+    let relResolveCacheIdentifier: string | undefined;
     if (parent) {
       // Fast path for (lazy loaded) modules in the same directory. The indirect
       // caching is required to allow cache invalidation without changing the old
@@ -385,6 +389,7 @@ class Module {
 
     Module._cache[filename] = module;
     if (parent !== undefined) {
+      assert(relResolveCacheIdentifier);
       relativeResolveCache[relResolveCacheIdentifier] = filename;
     }
 
@@ -397,6 +402,7 @@ class Module {
       if (threw) {
         delete Module._cache[filename];
         if (parent !== undefined) {
+          assert(relResolveCacheIdentifier);
           delete relativeResolveCache[relResolveCacheIdentifier];
         }
       } else if (
@@ -602,7 +608,7 @@ for (const id of nativeModulePolyfill.keys()) {
   Module.builtinModules.push(id);
 }
 
-let modulePaths = [];
+let modulePaths: string[] = [];
 
 // Given a module name, and a list of paths to test, returns the first
 // matching file in the following precedence.
@@ -664,7 +670,7 @@ function readPackage(requestPath: string): PackageInfo | null {
 }
 
 function readPackageScope(
-  checkPath
+  checkPath: string
 ): { path: string; data: PackageInfo } | false {
   const rootSeparatorIndex = checkPath.indexOf(path.sep);
   let separatorIndex;
@@ -987,6 +993,7 @@ const CircularRequirePrototypeWarningProxy = new Proxy(
   {
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
     get(target, prop): any {
+      // @ts-ignore
       if (prop in target) return target[prop];
       emitCircularRequireWarning(prop);
       return undefined;
@@ -1150,7 +1157,7 @@ function getPathFromURLWin32(url: URL): string {
   let pathname = url.pathname;
   for (let n = 0; n < pathname.length; n++) {
     if (pathname[n] === "%") {
-      const third = pathname.codePointAt(n + 2) | 0x20;
+      const third = pathname.codePointAt(n + 2)! | 0x20;
       if (
         (pathname[n + 1] === "2" && third === 102) || // 2f 2F /
         (pathname[n + 1] === "5" && third === 99)
@@ -1165,7 +1172,7 @@ function getPathFromURLWin32(url: URL): string {
   pathname = pathname.replace(forwardSlashRegEx, "\\");
   pathname = decodeURIComponent(pathname);
   // TODO: handle windows hostname case (needs bindings)
-  const letter = pathname.codePointAt(1) | 0x20;
+  const letter = pathname.codePointAt(1)! | 0x20;
   const sep = pathname[2];
   if (
     letter < CHAR_LOWERCASE_A ||
@@ -1184,7 +1191,7 @@ function getPathFromURLPosix(url: URL): string {
   const pathname = url.pathname;
   for (let n = 0; n < pathname.length; n++) {
     if (pathname[n] === "%") {
-      const third = pathname.codePointAt(n + 2) | 0x20;
+      const third = pathname.codePointAt(n + 2)! | 0x20;
       if (pathname[n + 1] === "2" && third === 102) {
         throw new Error(
           "Invalid file URL path: must not include encoded / characters"

std/node/os.ts

@@ -123,7 +123,7 @@ export function getPriority(pid = 0): number {
 }
 
 /** Returns the string path of the current user's home directory. */
-export function homedir(): string {
+export function homedir(): string | null {
   return Deno.dir("home");
 }
 
@@ -157,7 +157,7 @@ export function release(): string {
 
 /** Not yet implemented */
 export function setPriority(pid: number, priority?: number): void {
-  /* The node API has the 'pid' as the first parameter and as optional.  
+  /* The node API has the 'pid' as the first parameter and as optional.
        This makes for a problematic implementation in Typescript. */
   if (priority === undefined) {
     priority = pid;

std/path/utils.ts

@@ -46,13 +46,13 @@ export function normalizeString(
   let lastSegmentLength = 0;
   let lastSlash = -1;
   let dots = 0;
-  let code: number;
+  let code: number | undefined;
   for (let i = 0, len = path.length; i <= len; ++i) {
     if (i < len) code = path.charCodeAt(i);
-    else if (isPathSeparator(code)) break;
+    else if (isPathSeparator(code!)) break;
     else code = CHAR_FORWARD_SLASH;
 
-    if (isPathSeparator(code)) {
+    if (isPathSeparator(code!)) {
       if (lastSlash === i - 1 || dots === 1) {
         // NOOP
       } else if (lastSlash !== i - 1 && dots === 2) {

std/path/win32.ts

@@ -303,7 +303,7 @@ export function join(...paths: string[]): string {
   if (pathsCount === 0) return ".";
 
   let joined: string | undefined;
-  let firstPart: string;
+  let firstPart: string | null = null;
   for (let i = 0; i < pathsCount; ++i) {
     const path = paths[i];
     assertPath(path);

std/textproto/mod.ts

@@ -67,7 +67,7 @@ export class TextProtoReader {
    */
   async readMIMEHeader(): Promise<Headers | Deno.EOF> {
     const m = new Headers();
-    let line: Uint8Array;
+    let line: Uint8Array | undefined;
 
     // The first line cannot start with a leading space.
     let buf = await this.r.peek(1);
@@ -135,7 +135,7 @@ export class TextProtoReader {
 
   async readLineSlice(): Promise<Uint8Array | Deno.EOF> {
     // this.closeDot();
-    let line: Uint8Array;
+    let line: Uint8Array | undefined;
     while (true) {
       const r = await this.r.readLine();
       if (r === Deno.EOF) return Deno.EOF;

std/util/deep_assign.ts

@@ -1,4 +1,6 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+import { assert } from "../testing/asserts.ts";
+
 export function deepAssign(
   target: Record<string, unknown>,
   ...sources: object[]
@@ -24,6 +26,7 @@ export function deepAssign(
       if (typeof target[key] !== `object` || !target[key]) {
         target[key] = {};
       }
+      assert(value);
       deepAssign(target[key] as Record<string, unknown>, value);
     });
   }