diff --git a/README.md b/README.md
index 6f5f8dc899..ef88d14af4 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,16 @@
 # rust-python-linter
 
+A [Pyflakes](https://github.com/PyCQA/pyflakes)-inspired Python linter, written in Rust.
+
+Supports:
+
+- Python 3.10
+- True parallelism
+- [ESLint](https://eslint.org/docs/latest/user-guide/command-line-interface#caching)-inspired
+  caching
+
 ```
 cargo fmt
 cargo clippy
-cargo run test_sources
+cargo run resources/test/src
 ```
diff --git a/test_sources/__init__.py b/resources/test/src/__init__.py
similarity index 100%
rename from test_sources/__init__.py
rename to resources/test/src/__init__.py
diff --git a/resources/test/src/bar.py b/resources/test/src/bar.py
new file mode 100644
index 0000000000..d0c5c49e10
--- /dev/null
+++ b/resources/test/src/bar.py
@@ -0,0 +1,8 @@
+if (1, 2):
+    pass
+
+for _ in range(5):
+    if True:
+        pass
+    elif (1, 2):
+        pass
diff --git a/test_sources/foo.py b/resources/test/src/foo.py
similarity index 100%
rename from test_sources/foo.py
rename to resources/test/src/foo.py
diff --git a/src/check.rs b/src/check.rs
index 195da0cb65..811916a2ff 100644
--- a/src/check.rs
+++ b/src/check.rs
@@ -1,57 +1,94 @@
 use std::path::Path;
 
-use rustpython_parser::ast::{Located, StmtKind, Suite};
+use rustpython_parser::ast::{ExprKind, Stmt, StmtKind, Suite};
 
 use crate::message::Message;
 
-pub fn check_ast(path: &Path, python_ast: &Suite) -> Vec<Message> {
+fn check_statement(path: &Path, stmt: &Stmt) -> Vec<Message> {
     let mut messages: Vec<Message> = vec![];
-    for statement in python_ast {
-        let Located {
-            location,
-            custom: _,
-            node,
-        } = statement;
-        match node {
-            StmtKind::FunctionDef { .. } => {}
-            StmtKind::AsyncFunctionDef { .. } => {}
-            StmtKind::ClassDef { .. } => {}
-            StmtKind::Return { .. } => {}
-            StmtKind::Delete { .. } => {}
-            StmtKind::Assign { .. } => {}
-            StmtKind::AugAssign { .. } => {}
-            StmtKind::AnnAssign { .. } => {}
-            StmtKind::For { .. } => {}
-            StmtKind::AsyncFor { .. } => {}
-            StmtKind::While { .. } => {}
-            StmtKind::If { .. } => {}
-            StmtKind::With { .. } => {}
-            StmtKind::AsyncWith { .. } => {}
-            StmtKind::Raise { .. } => {}
-            StmtKind::Try { .. } => {}
-            StmtKind::Assert { .. } => {}
-            StmtKind::Import { .. } => {}
-            StmtKind::ImportFrom {
-                level: _,
-                module: _,
-                names,
-            } => {
-                for alias in names {
-                    if alias.name == "*" {
-                        messages.push(Message::ImportStarUsage {
-                            filename: path.to_path_buf(),
-                            location: *location,
-                        });
-                    }
+    match &stmt.node {
+        StmtKind::FunctionDef { body, .. } => {
+            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
+        }
+        StmtKind::AsyncFunctionDef { body, .. } => {
+            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
+        }
+        StmtKind::ClassDef { body, .. } => {
+            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
+        }
+        StmtKind::Return { .. } => {}
+        StmtKind::Delete { .. } => {}
+        StmtKind::Assign { .. } => {}
+        StmtKind::AugAssign { .. } => {}
+        StmtKind::AnnAssign { .. } => {}
+        StmtKind::For { body, orelse, .. } => {
+            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
+            messages.extend(orelse.iter().flat_map(|stmt| check_statement(path, stmt)));
+        }
+        StmtKind::AsyncFor { body, orelse, .. } => {
+            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
+            messages.extend(orelse.iter().flat_map(|stmt| check_statement(path, stmt)));
+        }
+        StmtKind::While { body, orelse, .. } => {
+            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
+            messages.extend(orelse.iter().flat_map(|stmt| check_statement(path, stmt)));
+        }
+        StmtKind::If { test, body, orelse } => {
+            if let ExprKind::Tuple { .. } = test.node {
+                messages.push(Message::IfTuple {
+                    filename: path.to_path_buf(),
+                    location: stmt.location,
+                });
+            }
+            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
+            messages.extend(orelse.iter().flat_map(|stmt| check_statement(path, stmt)));
+        }
+        StmtKind::With { body, .. } => {
+            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
+        }
+        StmtKind::AsyncWith { body, .. } => {
+            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
+        }
+        StmtKind::Raise { .. } => {}
+        StmtKind::Try {
+            body,
+            orelse,
+            finalbody,
+            ..
+        } => {
+            messages.extend(body.iter().flat_map(|stmt| check_statement(path, stmt)));
+            messages.extend(orelse.iter().flat_map(|stmt| check_statement(path, stmt)));
+            messages.extend(
+                finalbody
+                    .iter()
+                    .flat_map(|stmt| check_statement(path, stmt)),
+            );
+        }
+        StmtKind::Assert { .. } => {}
+        StmtKind::Import { .. } => {}
+        StmtKind::ImportFrom { names, .. } => {
+            for alias in names {
+                if alias.name == "*" {
+                    messages.push(Message::ImportStarUsage {
+                        filename: path.to_path_buf(),
+                        location: stmt.location,
+                    });
                 }
             }
-            StmtKind::Global { .. } => {}
-            StmtKind::Nonlocal { .. } => {}
-            StmtKind::Expr { .. } => {}
-            StmtKind::Pass => {}
-            StmtKind::Break => {}
-            StmtKind::Continue => {}
         }
+        StmtKind::Global { .. } => {}
+        StmtKind::Nonlocal { .. } => {}
+        StmtKind::Expr { .. } => {}
+        StmtKind::Pass => {}
+        StmtKind::Break => {}
+        StmtKind::Continue => {}
     }
     messages
 }
+
+pub fn check_ast(path: &Path, python_ast: &Suite) -> Vec<Message> {
+    python_ast
+        .iter()
+        .flat_map(|stmt| check_statement(path, stmt))
+        .collect()
+}
diff --git a/src/message.rs b/src/message.rs
index 94e0b67b83..31a62709e7 100644
--- a/src/message.rs
+++ b/src/message.rs
@@ -27,26 +27,27 @@ pub enum Message {
         #[serde(with = "LocationDef")]
         location: Location,
     },
+    IfTuple {
+        filename: PathBuf,
+        #[serde(with = "LocationDef")]
+        location: Location,
+    },
 }
 
 impl Message {
     /// A four-letter shorthand code for the message.
     pub fn code(&self) -> &'static str {
         match self {
-            Message::ImportStarUsage {
-                filename: _,
-                location: _,
-            } => "F403",
+            Message::ImportStarUsage { .. } => "F403",
+            Message::IfTuple { .. } => "F634",
         }
     }
 
     /// The body text for the message.
     pub fn body(&self) -> &'static str {
         match self {
-            Message::ImportStarUsage {
-                filename: _,
-                location: _,
-            } => "Unable to detect undefined names",
+            Message::ImportStarUsage { .. } => "Unable to detect undefined names",
+            Message::IfTuple { .. } => "If test is a tuple, which is always `True`",
         }
     }
 }
@@ -65,6 +66,17 @@ impl fmt::Display for Message {
                 self.code().red().bold(),
                 self.body()
             ),
+            Message::IfTuple { filename, location } => write!(
+                f,
+                "{}{}{}{}{}\t{}\t{}",
+                filename.to_string_lossy().white().bold(),
+                ":".cyan(),
+                location.column(),
+                ":".cyan(),
+                location.row(),
+                self.code().red().bold(),
+                self.body()
+            ),
         }
     }
 }
diff --git a/test_sources/bar.py b/test_sources/bar.py
deleted file mode 100644
index e69de29bb2..0000000000