fix(unstable): move sloppy-import warnings to lint rule (#24710)

Adds a new `no-sloppy-imports` lint rule and cleans up the lint code.

Closes #22844
Closes https://github.com/denoland/deno_lint/issues/1293

42 files changed, 377 insertions, 190 deletions

diff --git a/tests/integration/check_tests.rs b/tests/integration/check_tests.rs
index 78ab859f9..b560b352e 100644
--- a/tests/integration/check_tests.rs
+++ b/tests/integration/check_tests.rs
@@ -392,105 +392,3 @@ fn npm_module_check_then_error() {
     .assert_matches_text("Check [WILDCARD]main.ts\nerror: TS2305[WILDCARD]has no exported member 'oldName'[WILDCARD]")
     .assert_exit_code(1);
 }
-
-#[test]
-fn test_unstable_sloppy_imports_dts_files() {
-  let context = TestContextBuilder::new().use_temp_cwd().build();
-  let temp_dir = context.temp_dir();
-  temp_dir.write("a.ts", "export class A {}"); // resolves this
-  temp_dir.write("a.d.ts", "export class A2 {}");
-
-  temp_dir.write("b.js", "export class B {}");
-  temp_dir.write("b.d.ts", "export class B2 {}"); // this
-
-  temp_dir.write("c.mts", "export class C {}"); // this
-  temp_dir.write("c.d.mts", "export class C2 {}");
-
-  temp_dir.write("d.mjs", "export class D {}");
-  temp_dir.write("d.d.mts", "export class D2 {}"); // this
-
-  let temp_dir = temp_dir.path();
-
-  let dir = temp_dir.join("dir_ts");
-  dir.create_dir_all();
-  dir.join("index.ts").write("export class Dir {}"); // this
-  dir.join("index.d.ts").write("export class Dir2 {}");
-
-  let dir = temp_dir.join("dir_js");
-  dir.create_dir_all();
-  dir.join("index.js").write("export class Dir {}");
-  dir.join("index.d.ts").write("export class Dir2 {}"); // this
-
-  let dir = temp_dir.join("dir_mts");
-  dir.create_dir_all();
-  dir.join("index.mts").write("export class Dir {}"); // this
-  dir.join("index.d.ts").write("export class Dir2 {}");
-
-  let dir = temp_dir.join("dir_mjs");
-  dir.create_dir_all();
-  dir.join("index.mjs").write("export class Dir {}");
-  dir.join("index.d.ts").write("export class Dir2 {}"); // this
-
-  temp_dir.join("main.ts").write(
-    r#"import * as a from "./a.js";
-import * as b from "./b.js";
-import * as c from "./c.mjs";
-import * as d from "./d.mjs";
-
-console.log(a.A);
-console.log(b.B2);
-console.log(c.C);
-console.log(d.D2);
-
-import * as a2 from "./a";
-import * as b2 from "./b";
-import * as c2 from "./c";
-import * as d2 from "./d";
-
-console.log(a2.A);
-console.log(b2.B2);
-console.log(c2.C);
-console.log(d2.D2);
-
-import * as dirTs from "./dir_ts";
-import * as dirJs from "./dir_js";
-import * as dirMts from "./dir_mts";
-import * as dirMjs from "./dir_mjs";
-
-console.log(dirTs.Dir);
-console.log(dirJs.Dir2);
-console.log(dirMts.Dir);
-console.log(dirMjs.Dir2);
-"#,
-  );
-
-  context
-    .new_command()
-    .args("check --unstable-sloppy-imports main.ts")
-    .run()
-    .assert_matches_text(
-      r#"Warning Sloppy module resolution (hint: update .js extension to .ts)
-    at file:///[WILDCARD]/main.ts:1:20
-Warning Sloppy module resolution (hint: update .mjs extension to .mts)
-    at file:///[WILDCARD]/main.ts:3:20
-Warning Sloppy module resolution (hint: add .ts extension)
-    at file:///[WILDCARD]/main.ts:11:21
-Warning Sloppy module resolution (hint: add .js extension)
-    at file:///[WILDCARD]/main.ts:12:21
-Warning Sloppy module resolution (hint: add .mts extension)
-    at file:///[WILDCARD]/main.ts:13:21
-Warning Sloppy module resolution (hint: add .mjs extension)
-    at file:///[WILDCARD]/main.ts:14:21
-Warning Sloppy module resolution (hint: specify path to index.ts file in directory instead)
-    at file:///[WILDCARD]/main.ts:21:24
-Warning Sloppy module resolution (hint: specify path to index.js file in directory instead)
-    at file:///[WILDCARD]/main.ts:22:24
-Warning Sloppy module resolution (hint: specify path to index.mts file in directory instead)
-    at file:///[WILDCARD]/main.ts:23:25
-Warning Sloppy module resolution (hint: specify path to index.mjs file in directory instead)
-    at file:///[WILDCARD]/main.ts:24:25
-Check [WILDCARD]main.ts
-"#,
-    )
-    .assert_exit_code(0);
-}
diff --git a/tests/integration/lsp_tests.rs b/tests/integration/lsp_tests.rs
index e8904942d..cbc175ec6 100644
--- a/tests/integration/lsp_tests.rs
+++ b/tests/integration/lsp_tests.rs
@@ -14459,7 +14459,67 @@ fn lsp_sloppy_imports() {
     },
   }));
 
-  assert_eq!(json!(diagnostics.all()), json!([]));
+  assert_eq!(
+    json!(diagnostics.all()),
+    json!([{
+    "range": {
+          "start": { "line": 0, "character": 19 },
+          "end": { "line": 0, "character": 24 }
+        },
+        "severity": 2,
+        "code": "no-sloppy-imports",
+        "source": "deno-lint",
+        "message": "Sloppy imports are not allowed.",
+        "data": [{
+          "description": "Add a '.ts' extension.",
+          "changes": [{
+            "range": {
+              "start": { "line": 0, "character": 19 },
+              "end": { "line": 0, "character": 24 },
+            },
+           "new_text": "'./a.ts'"
+          }]
+        }]
+    }, {
+    "range": {
+        "start": { "line": 1, "character": 19 },
+        "end": { "line": 1, "character": 27 }
+      },
+      "severity": 2,
+      "code": "no-sloppy-imports",
+      "source": "deno-lint",
+      "message": "Sloppy imports are not allowed.",
+      "data": [{
+        "description": "Change the extension to '.ts'.",
+        "changes": [{
+          "range": {
+            "start": { "line": 1, "character": 19 },
+            "end": { "line": 1, "character": 27 },
+          },
+         "new_text": "'./b.ts'"
+        }]
+      }]
+    }, {
+    "range": {
+        "start": { "line": 2, "character": 19 },
+        "end": { "line": 2, "character": 27 }
+      },
+      "severity": 2,
+      "code": "no-sloppy-imports",
+      "source": "deno-lint",
+      "message": "Sloppy imports are not allowed.",
+      "data": [{
+        "description": "Change the extension to '.d.ts'.",
+        "changes": [{
+          "range": {
+            "start": { "line": 2, "character": 19 },
+            "end": { "line": 2, "character": 27 },
+          },
+         "new_text": "'./c.d.ts'"
+        }]
+      }]
+    }])
+  );
 
   client.shutdown();
 }
@@ -14488,11 +14548,33 @@ fn lsp_sloppy_imports_prefers_dts() {
     "import { foo } from './a.js';\nconsole.log(foo);",
   );
   let diagnostics = client.did_open_file(&file);
-  // no warnings because "a.js" exists
-  assert_eq!(diagnostics.all().len(), 0);
+  // no other warnings because "a.js" exists
+  assert_eq!(
+    json!(diagnostics.all()),
+    json!([{
+      "range": {
+        "start": { "line": 0, "character": 20 },
+        "end": { "line": 0, "character": 28 }
+      },
+      "severity": 2,
+      "code": "no-sloppy-imports",
+      "source": "deno-lint",
+      "message": "Sloppy imports are not allowed.",
+      "data": [{
+        "description": "Change the extension to '.d.ts'.",
+        "changes": [{
+          "range": {
+            "start": { "line": 0, "character": 20 },
+            "end": { "line": 0, "character": 28 },
+          },
+         "new_text": "'./a.d.ts'"
+        }]
+      }]
+    }])
+  );
 
   let diagnostics = client.did_open_file(&a_dts);
-  assert_eq!(diagnostics.all().len(), 0, "Got {:#?}", diagnostics.all());
+  assert_eq!(json!(diagnostics.for_file(&a_dts.uri())), json!([]));
 
   let response = client.write_request(
     "textDocument/references",
diff --git a/tests/integration/run_tests.rs b/tests/integration/run_tests.rs
index 73d98aff5..7a6ee61cf 100644
--- a/tests/integration/run_tests.rs
+++ b/tests/integration/run_tests.rs
@@ -4851,86 +4851,6 @@ itest!(unsafe_proto_flag {
   exit_code: 0,
 });
 
-#[test]
-fn test_unstable_sloppy_imports() {
-  let context = TestContextBuilder::new().use_temp_cwd().build();
-  let temp_dir = context.temp_dir();
-  temp_dir.write("a.ts", "export class A {}");
-  temp_dir.write("b.js", "export class B {}");
-  temp_dir.write("c.mts", "export class C {}");
-  temp_dir.write("d.mjs", "export class D {}");
-  temp_dir.write("e.tsx", "export class E {}");
-  temp_dir.write("f.jsx", "export class F {}");
-  let dir = temp_dir.path().join("dir");
-  dir.create_dir_all();
-  dir.join("index.tsx").write("export class G {}");
-  temp_dir.write(
-    "main.ts",
-    r#"import * as a from "./a.js";
-import * as b from "./b";
-import * as c from "./c";
-import * as d from "./d";
-import * as e from "./e";
-import * as e2 from "./e.js";
-import * as f from "./f";
-import * as g from "./dir";
-console.log(a.A);
-console.log(b.B);
-console.log(c.C);
-console.log(d.D);
-console.log(e.E);
-console.log(e2.E);
-console.log(f.F);
-console.log(g.G);
-"#,
-  );
-
-  // run without sloppy imports
-  context
-    .new_command()
-    .args("run main.ts")
-    .run()
-    .assert_matches_text(r#"error: Module not found "file:///[WILDCARD]/a.js". Maybe change the extension to '.ts' or run with --unstable-sloppy-imports
-    at file:///[WILDCARD]/main.ts:1:20
-"#)
-    .assert_exit_code(1);
-
-  // now run with sloppy imports
-  temp_dir.write("deno.json", r#"{ "unstable": ["sloppy-imports"] }"#);
-  context
-    .new_command()
-    .args("run main.ts")
-    .run()
-    .assert_matches_text(
-      "Warning Sloppy imports are not recommended and have a negative impact on performance.
-Warning Sloppy module resolution (hint: update .js extension to .ts)
-    at file:///[WILDCARD]/main.ts:1:20
-Warning Sloppy module resolution (hint: add .js extension)
-    at file:///[WILDCARD]/main.ts:2:20
-Warning Sloppy module resolution (hint: add .mts extension)
-    at file:///[WILDCARD]/main.ts:3:20
-Warning Sloppy module resolution (hint: add .mjs extension)
-    at file:///[WILDCARD]/main.ts:4:20
-Warning Sloppy module resolution (hint: add .tsx extension)
-    at file:///[WILDCARD]/main.ts:5:20
-Warning Sloppy module resolution (hint: update .js extension to .tsx)
-    at file:///[WILDCARD]/main.ts:6:21
-Warning Sloppy module resolution (hint: add .jsx extension)
-    at file:///[WILDCARD]/main.ts:7:20
-Warning Sloppy module resolution (hint: specify path to index.tsx file in directory instead)
-    at file:///[WILDCARD]/main.ts:8:20
-[class A]
-[class B]
-[class C]
-[class D]
-[class E]
-[class E]
-[class F]
-[class G]
-",
-    );
-}
-
 itest!(unstable_temporal_api {
   args: "run --no-config --unstable-temporal --check run/unstable_temporal_api/main.ts",
   output: "run/unstable_temporal_api/main.out",
diff --git a/tests/specs/lint/sloppy_imports_dts/__test__.jsonc b/tests/specs/lint/sloppy_imports_dts/__test__.jsonc
new file mode 100644
index 000000000..2650d7ec2
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/__test__.jsonc
@@ -0,0 +1,34 @@
+{
+  "tests": {
+    "check": {
+      "args": "check --unstable-sloppy-imports main.ts",
+      "output": "check.out"
+    },
+    "run": {
+      "args": "run --unstable-sloppy-imports main.ts",
+      "output": "run.out"
+    },
+    "lint": {
+      "args": "lint --unstable-sloppy-imports",
+      "output": "lint.out",
+      "exitCode": 1
+    },
+    // try fixing the lint issues and then ensure deno check and run still work
+    "lint_fix": {
+      "tempDir": true,
+      "steps": [{
+        "args": "lint --unstable-sloppy-imports --fix",
+        "output": "Checked 17 files\n"
+      }, {
+        "args": "lint --unstable-sloppy-imports",
+        "output": "Checked 17 files\n"
+      }, {
+        "args": "check --unstable-sloppy-imports main.ts",
+        "output": "check.out"
+      }, {
+        "args": "run --unstable-sloppy-imports main.ts",
+        "output": "run.out"
+      }]
+    }
+  }
+}
diff --git a/tests/specs/lint/sloppy_imports_dts/a.d.ts b/tests/specs/lint/sloppy_imports_dts/a.d.ts
new file mode 100644
index 000000000..b0c84214f
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/a.d.ts
@@ -0,0 +1 @@
+export class A2 {}
diff --git a/tests/specs/lint/sloppy_imports_dts/a.ts b/tests/specs/lint/sloppy_imports_dts/a.ts
new file mode 100644
index 000000000..1e14df544
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/a.ts
@@ -0,0 +1 @@
+export class A {}
diff --git a/tests/specs/lint/sloppy_imports_dts/b.d.ts b/tests/specs/lint/sloppy_imports_dts/b.d.ts
new file mode 100644
index 000000000..522d6784d
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/b.d.ts
@@ -0,0 +1 @@
+export class B2 {}
diff --git a/tests/specs/lint/sloppy_imports_dts/b.js b/tests/specs/lint/sloppy_imports_dts/b.js
new file mode 100644
index 000000000..1aa41a54a
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/b.js
@@ -0,0 +1 @@
+export class B {}
diff --git a/tests/specs/lint/sloppy_imports_dts/c.d.mts b/tests/specs/lint/sloppy_imports_dts/c.d.mts
new file mode 100644
index 000000000..efd6dcc73
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/c.d.mts
@@ -0,0 +1 @@
+export class C2 {}
diff --git a/tests/specs/lint/sloppy_imports_dts/c.mts b/tests/specs/lint/sloppy_imports_dts/c.mts
new file mode 100644
index 000000000..1ec0ebf40
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/c.mts
@@ -0,0 +1 @@
+export class C {}
diff --git a/tests/specs/lint/sloppy_imports_dts/check.out b/tests/specs/lint/sloppy_imports_dts/check.out
new file mode 100644
index 000000000..1830c3186
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/check.out
@@ -0,0 +1 @@
+Check file:///[WILDLINE]/main.ts
diff --git a/tests/specs/lint/sloppy_imports_dts/d.d.mts b/tests/specs/lint/sloppy_imports_dts/d.d.mts
new file mode 100644
index 000000000..629b29e30
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/d.d.mts
@@ -0,0 +1 @@
+export class D2 {}
diff --git a/tests/specs/lint/sloppy_imports_dts/d.mjs b/tests/specs/lint/sloppy_imports_dts/d.mjs
new file mode 100644
index 000000000..01b958f66
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/d.mjs
@@ -0,0 +1 @@
+export class D {}
diff --git a/tests/specs/lint/sloppy_imports_dts/dir_js/index.d.ts b/tests/specs/lint/sloppy_imports_dts/dir_js/index.d.ts
new file mode 100644
index 000000000..23cac8500
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/dir_js/index.d.ts
@@ -0,0 +1 @@
+export class Dir2 {}
diff --git a/tests/specs/lint/sloppy_imports_dts/dir_js/index.js b/tests/specs/lint/sloppy_imports_dts/dir_js/index.js
new file mode 100644
index 000000000..f31e303be
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/dir_js/index.js
@@ -0,0 +1 @@
+export class Dir {}
diff --git a/tests/specs/lint/sloppy_imports_dts/dir_mjs/index.d.ts b/tests/specs/lint/sloppy_imports_dts/dir_mjs/index.d.ts
new file mode 100644
index 000000000..23cac8500
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/dir_mjs/index.d.ts
@@ -0,0 +1 @@
+export class Dir2 {}
diff --git a/tests/specs/lint/sloppy_imports_dts/dir_mjs/index.mjs b/tests/specs/lint/sloppy_imports_dts/dir_mjs/index.mjs
new file mode 100644
index 000000000..f31e303be
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/dir_mjs/index.mjs
@@ -0,0 +1 @@
+export class Dir {}
diff --git a/tests/specs/lint/sloppy_imports_dts/dir_mts/index.d.ts b/tests/specs/lint/sloppy_imports_dts/dir_mts/index.d.ts
new file mode 100644
index 000000000..23cac8500
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/dir_mts/index.d.ts
@@ -0,0 +1 @@
+export class Dir2 {}
diff --git a/tests/specs/lint/sloppy_imports_dts/dir_mts/index.mts b/tests/specs/lint/sloppy_imports_dts/dir_mts/index.mts
new file mode 100644
index 000000000..f31e303be
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/dir_mts/index.mts
@@ -0,0 +1 @@
+export class Dir {}
diff --git a/tests/specs/lint/sloppy_imports_dts/dir_ts/index.d.ts b/tests/specs/lint/sloppy_imports_dts/dir_ts/index.d.ts
new file mode 100644
index 000000000..23cac8500
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/dir_ts/index.d.ts
@@ -0,0 +1 @@
+export class Dir2 {}
diff --git a/tests/specs/lint/sloppy_imports_dts/dir_ts/index.ts b/tests/specs/lint/sloppy_imports_dts/dir_ts/index.ts
new file mode 100644
index 000000000..f31e303be
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/dir_ts/index.ts
@@ -0,0 +1 @@
+export class Dir {}
diff --git a/tests/specs/lint/sloppy_imports_dts/lint.out b/tests/specs/lint/sloppy_imports_dts/lint.out
new file mode 100644
index 000000000..d891676ac
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/lint.out
@@ -0,0 +1,110 @@
+error[no-sloppy-imports]: Sloppy imports are not allowed.
+ --> [WILDLINE]main.ts:1:20
+  | 
+1 | import * as a from "./a.js";
+  |                    ^^^^^^^^
+
+  docs: https://docs.deno.com/runtime/manual/tools/unstable_flags/#--unstable-sloppy-imports
+
+
+error[no-sloppy-imports]: Sloppy imports are not allowed.
+ --> [WILDLINE]main.ts:2:20
+  | 
+2 | import * as b from "./b.js";
+  |                    ^^^^^^^^
+
+  docs: https://docs.deno.com/runtime/manual/tools/unstable_flags/#--unstable-sloppy-imports
+
+
+error[no-sloppy-imports]: Sloppy imports are not allowed.
+ --> [WILDLINE]main.ts:3:20
+  | 
+3 | import * as c from "./c.mjs";
+  |                    ^^^^^^^^^
+
+  docs: https://docs.deno.com/runtime/manual/tools/unstable_flags/#--unstable-sloppy-imports
+
+
+error[no-sloppy-imports]: Sloppy imports are not allowed.
+ --> [WILDLINE]main.ts:4:20
+  | 
+4 | import * as d from "./d.mjs";
+  |                    ^^^^^^^^^
+
+  docs: https://docs.deno.com/runtime/manual/tools/unstable_flags/#--unstable-sloppy-imports
+
+
+error[no-sloppy-imports]: Sloppy imports are not allowed.
+  --> [WILDLINE]main.ts:11:21
+   | 
+11 | import * as a2 from "./a";
+   |                     ^^^^^
+
+  docs: https://docs.deno.com/runtime/manual/tools/unstable_flags/#--unstable-sloppy-imports
+
+
+error[no-sloppy-imports]: Sloppy imports are not allowed.
+  --> [WILDLINE]main.ts:12:21
+   | 
+12 | import * as b2 from "./b";
+   |                     ^^^^^
+
+  docs: https://docs.deno.com/runtime/manual/tools/unstable_flags/#--unstable-sloppy-imports
+
+
+error[no-sloppy-imports]: Sloppy imports are not allowed.
+  --> [WILDLINE]main.ts:13:21
+   | 
+13 | import * as c2 from "./c";
+   |                     ^^^^^
+
+  docs: https://docs.deno.com/runtime/manual/tools/unstable_flags/#--unstable-sloppy-imports
+
+
+error[no-sloppy-imports]: Sloppy imports are not allowed.
+  --> [WILDLINE]main.ts:14:21
+   | 
+14 | import * as d2 from "./d";
+   |                     ^^^^^
+
+  docs: https://docs.deno.com/runtime/manual/tools/unstable_flags/#--unstable-sloppy-imports
+
+
+error[no-sloppy-imports]: Sloppy imports are not allowed.
+  --> [WILDLINE]main.ts:21:24
+   | 
+21 | import * as dirTs from "./dir_ts";
+   |                        ^^^^^^^^^^
+
+  docs: https://docs.deno.com/runtime/manual/tools/unstable_flags/#--unstable-sloppy-imports
+
+
+error[no-sloppy-imports]: Sloppy imports are not allowed.
+  --> [WILDLINE]main.ts:22:24
+   | 
+22 | import * as dirJs from "./dir_js";
+   |                        ^^^^^^^^^^
+
+  docs: https://docs.deno.com/runtime/manual/tools/unstable_flags/#--unstable-sloppy-imports
+
+
+error[no-sloppy-imports]: Sloppy imports are not allowed.
+  --> [WILDLINE]main.ts:23:25
+   | 
+23 | import * as dirMts from "./dir_mts";
+   |                         ^^^^^^^^^^^
+
+  docs: https://docs.deno.com/runtime/manual/tools/unstable_flags/#--unstable-sloppy-imports
+
+
+error[no-sloppy-imports]: Sloppy imports are not allowed.
+  --> [WILDLINE]main.ts:24:25
+   | 
+24 | import * as dirMjs from "./dir_mjs";
+   |                         ^^^^^^^^^^^
+
+  docs: https://docs.deno.com/runtime/manual/tools/unstable_flags/#--unstable-sloppy-imports
+
+
+Found 12 problems (12 fixable via --fix)
+Checked 17 files
diff --git a/tests/specs/lint/sloppy_imports_dts/main.ts b/tests/specs/lint/sloppy_imports_dts/main.ts
new file mode 100644
index 000000000..2261eae58
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/main.ts
@@ -0,0 +1,29 @@
+import * as a from "./a.js";
+import * as b from "./b.js";
+import * as c from "./c.mjs";
+import * as d from "./d.mjs";
+
+console.log(a.A);
+console.log(b.B2);
+console.log(c.C);
+console.log(d.D2);
+
+import * as a2 from "./a";
+import * as b2 from "./b";
+import * as c2 from "./c";
+import * as d2 from "./d";
+
+console.log(a2.A);
+console.log(b2.B2);
+console.log(c2.C);
+console.log(d2.D2);
+
+import * as dirTs from "./dir_ts";
+import * as dirJs from "./dir_js";
+import * as dirMts from "./dir_mts";
+import * as dirMjs from "./dir_mjs";
+
+console.log(dirTs.Dir);
+console.log(dirJs.Dir2);
+console.log(dirMts.Dir);
+console.log(dirMjs.Dir2);
diff --git a/tests/specs/lint/sloppy_imports_dts/run.out b/tests/specs/lint/sloppy_imports_dts/run.out
new file mode 100644
index 000000000..665534c64
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_dts/run.out
@@ -0,0 +1,12 @@
+[class A]
+undefined
+[class C]
+undefined
+[class A]
+undefined
+[class C]
+undefined
+[class Dir]
+undefined
+[class Dir]
+undefined
diff --git a/tests/specs/lint/sloppy_imports_no_incremental_cache/__test__.jsonc b/tests/specs/lint/sloppy_imports_no_incremental_cache/__test__.jsonc
new file mode 100644
index 000000000..e4596fd21
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_no_incremental_cache/__test__.jsonc
@@ -0,0 +1,20 @@
+{
+  "tempDir": true,
+  "steps": [{
+    "args": "lint main.ts",
+    "output": "Checked 1 file\n"
+  }, {
+    "args": "lint --unstable-sloppy-imports main.ts",
+    "output": "Checked 1 file\n"
+  }, {
+    "args": [
+      "eval",
+      "Deno.renameSync('file.js', 'file.ts')"
+    ],
+    "output": ""
+  }, {
+    "args": "lint --unstable-sloppy-imports main.ts",
+    "output": "fail_js_to_ts.out",
+    "exitCode": 1
+  }]
+}
diff --git a/tests/specs/lint/sloppy_imports_no_incremental_cache/fail_js_to_ts.out b/tests/specs/lint/sloppy_imports_no_incremental_cache/fail_js_to_ts.out
new file mode 100644
index 000000000..7321fd184
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_no_incremental_cache/fail_js_to_ts.out
@@ -0,0 +1,11 @@
+error[no-sloppy-imports]: Sloppy imports are not allowed.
+ --> [WILDLINE]main.ts:1:23
+  | 
+1 | import * as file from "./file.js";
+  |                       ^^^^^^^^^^^
+
+  docs: https://docs.deno.com/runtime/manual/tools/unstable_flags/#--unstable-sloppy-imports
+
+
+Found 1 problem (1 fixable via --fix)
+Checked 1 file
diff --git a/tests/specs/lint/sloppy_imports_no_incremental_cache/file.js b/tests/specs/lint/sloppy_imports_no_incremental_cache/file.js
new file mode 100644
index 000000000..23f12c5f6
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_no_incremental_cache/file.js
@@ -0,0 +1 @@
+export class File {}
diff --git a/tests/specs/lint/sloppy_imports_no_incremental_cache/main.ts b/tests/specs/lint/sloppy_imports_no_incremental_cache/main.ts
new file mode 100644
index 000000000..873f4f483
--- /dev/null
+++ b/tests/specs/lint/sloppy_imports_no_incremental_cache/main.ts
@@ -0,0 +1,3 @@
+import * as file from "./file.js";
+
+console.log(file);
diff --git a/tests/specs/publish/sloppy_imports/sloppy_imports.out b/tests/specs/publish/sloppy_imports/sloppy_imports.out
index bfa258b93..9371e9bb6 100644
--- a/tests/specs/publish/sloppy_imports/sloppy_imports.out
+++ b/tests/specs/publish/sloppy_imports/sloppy_imports.out
@@ -1,5 +1,3 @@
-Warning Sloppy module resolution (hint: specify path to index.ts file in directory instead)
-    at file:///[WILDCARD]/mod.ts:1:20
 Check file:///[WILDCARD]/mod.ts
 Checking for slow types in the public API...
 Check file:///[WILDCARD]/mod.ts
diff --git a/tests/specs/run/sloppy_imports/__test__.jsonc b/tests/specs/run/sloppy_imports/__test__.jsonc
new file mode 100644
index 000000000..79aaaba69
--- /dev/null
+++ b/tests/specs/run/sloppy_imports/__test__.jsonc
@@ -0,0 +1,10 @@
+{
+  "steps": [{
+    "args": "run main.ts",
+    "output": "no_sloppy.out",
+    "exitCode": 1
+  }, {
+    "args": "run --unstable-sloppy-imports main.ts",
+    "output": "sloppy.out"
+  }]
+}
diff --git a/tests/specs/run/sloppy_imports/a.ts b/tests/specs/run/sloppy_imports/a.ts
new file mode 100644
index 000000000..1e14df544
--- /dev/null
+++ b/tests/specs/run/sloppy_imports/a.ts
@@ -0,0 +1 @@
+export class A {}
diff --git a/tests/specs/run/sloppy_imports/b.js b/tests/specs/run/sloppy_imports/b.js
new file mode 100644
index 000000000..1aa41a54a
--- /dev/null
+++ b/tests/specs/run/sloppy_imports/b.js
@@ -0,0 +1 @@
+export class B {}
diff --git a/tests/specs/run/sloppy_imports/c.mts b/tests/specs/run/sloppy_imports/c.mts
new file mode 100644
index 000000000..1ec0ebf40
--- /dev/null
+++ b/tests/specs/run/sloppy_imports/c.mts
@@ -0,0 +1 @@
+export class C {}
diff --git a/tests/specs/run/sloppy_imports/d.mjs b/tests/specs/run/sloppy_imports/d.mjs
new file mode 100644
index 000000000..01b958f66
--- /dev/null
+++ b/tests/specs/run/sloppy_imports/d.mjs
@@ -0,0 +1 @@
+export class D {}
diff --git a/tests/specs/run/sloppy_imports/dir/index.tsx b/tests/specs/run/sloppy_imports/dir/index.tsx
new file mode 100644
index 000000000..d679ef9a9
--- /dev/null
+++ b/tests/specs/run/sloppy_imports/dir/index.tsx
@@ -0,0 +1 @@
+export class G {}
diff --git a/tests/specs/run/sloppy_imports/e.tsx b/tests/specs/run/sloppy_imports/e.tsx
new file mode 100644
index 000000000..70e8d4378
--- /dev/null
+++ b/tests/specs/run/sloppy_imports/e.tsx
@@ -0,0 +1 @@
+export class E {}
diff --git a/tests/specs/run/sloppy_imports/f.jsx b/tests/specs/run/sloppy_imports/f.jsx
new file mode 100644
index 000000000..cee3fd259
--- /dev/null
+++ b/tests/specs/run/sloppy_imports/f.jsx
@@ -0,0 +1 @@
+export class F {}
diff --git a/tests/specs/run/sloppy_imports/main.ts b/tests/specs/run/sloppy_imports/main.ts
new file mode 100644
index 000000000..3bdc3fe01
--- /dev/null
+++ b/tests/specs/run/sloppy_imports/main.ts
@@ -0,0 +1,16 @@
+import * as a from "./a.js";
+import * as b from "./b";
+import * as c from "./c";
+import * as d from "./d";
+import * as e from "./e";
+import * as e2 from "./e.js";
+import * as f from "./f";
+import * as g from "./dir";
+console.log(a.A);
+console.log(b.B);
+console.log(c.C);
+console.log(d.D);
+console.log(e.E);
+console.log(e2.E);
+console.log(f.F);
+console.log(g.G);
diff --git a/tests/specs/run/sloppy_imports/no_sloppy.out b/tests/specs/run/sloppy_imports/no_sloppy.out
new file mode 100644
index 000000000..d3a205e99
--- /dev/null
+++ b/tests/specs/run/sloppy_imports/no_sloppy.out
@@ -0,0 +1,2 @@
+error: Module not found "file:///[WILDCARD]/a.js". Maybe change the extension to '.ts' or run with --unstable-sloppy-imports
+    at file:///[WILDLINE]/main.ts:1:20
diff --git a/tests/specs/run/sloppy_imports/sloppy.out b/tests/specs/run/sloppy_imports/sloppy.out
new file mode 100644
index 000000000..170a4bb16
--- /dev/null
+++ b/tests/specs/run/sloppy_imports/sloppy.out
@@ -0,0 +1,8 @@
+[class A]
+[class B]
+[class C]
+[class D]
+[class E]
+[class E]
+[class F]
+[class G]
diff --git a/tests/specs/task/invalid_unstable_feature/invalid_unstable_feature.out b/tests/specs/task/invalid_unstable_feature/invalid_unstable_feature.out
index 78c4eaca9..901eea47a 100644
--- a/tests/specs/task/invalid_unstable_feature/invalid_unstable_feature.out
+++ b/tests/specs/task/invalid_unstable_feature/invalid_unstable_feature.out
@@ -1,5 +1,4 @@
 Task start deno run index.js
-Warning Sloppy imports are not recommended and have a negative impact on performance.
 Warning 'abc' isn't a valid unstable feature
 Warning 'cba' isn't a valid unstable feature
 Hello unstable features
diff --git a/tests/util/server/src/lsp.rs b/tests/util/server/src/lsp.rs
index f21035610..b615ed475 100644
--- a/tests/util/server/src/lsp.rs
+++ b/tests/util/server/src/lsp.rs
@@ -1230,6 +1230,16 @@ impl CollectedDiagnostics {
       .collect()
   }
 
+  pub fn for_file(&self, specifier: &Url) -> Vec<lsp::Diagnostic> {
+    self
+      .all_messages()
+      .iter()
+      .filter(|p| p.uri == *specifier)
+      .flat_map(|p| p.diagnostics.iter())
+      .cloned()
+      .collect()
+  }
+
   /// Gets the messages that the editor will see after all the publishes.
   pub fn all_messages(&self) -> Vec<lsp::PublishDiagnosticsParams> {
     self.0.clone()
@@ -1245,7 +1255,7 @@ impl CollectedDiagnostics {
       .find(|p| {
         p.diagnostics
           .iter()
-          .any(|d| d.source == Some(source.to_string()))
+          .any(|d| d.source.as_deref() == Some(source))
       })
       .map(ToOwned::to_owned)
       .unwrap()