Add tests for stability check in completion

crates/ide-completion/src/tests/pattern.rs

@@ -1,12 +1,7 @@
 //! Completion tests for pattern position.
 use expect_test::{expect, Expect};
 
-use crate::tests::{check_edit, completion_list, BASE_ITEMS_FIXTURE};
-
-fn check_empty(ra_fixture: &str, expect: Expect) {
-    let actual = completion_list(ra_fixture);
-    expect.assert_eq(&actual)
-}
+use crate::tests::{check_edit, check_empty, completion_list, BASE_ITEMS_FIXTURE};
 
 fn check(ra_fixture: &str, expect: Expect) {
     let actual = completion_list(&format!("{BASE_ITEMS_FIXTURE}\n{ra_fixture}"));
@@ -742,3 +737,56 @@ fn f(x: EnumAlias<u8>) {
         "#]],
     );
 }
+
+#[test]
+fn pat_no_unstable_item_on_stable() {
+    check_empty(
+        r#"
+//- /main.rs crate:main deps:std
+use std::*;
+fn foo() {
+    let a$0
+}
+//- /std.rs crate:std
+#[unstable]
+pub struct S;
+#[unstable]
+pub enum Enum {
+    Variant
+}
+"#,
+        expect![[r#"
+            md std
+            kw mut
+            kw ref
+        "#]],
+    );
+}
+
+#[test]
+fn pat_unstable_item_on_nightly() {
+    check_empty(
+        r#"
+//- toolchain:nightly
+//- /main.rs crate:main deps:std
+use std::*;
+fn foo() {
+    let a$0
+}
+//- /std.rs crate:std
+#[unstable]
+pub struct S;
+#[unstable]
+pub enum Enum {
+    Variant
+}
+"#,
+        expect![[r#"
+            en Enum
+            md std
+            st S
+            kw mut
+            kw ref
+        "#]],
+    );
+}