feat(linter/import) implement no_unused_modules rule (#2720)

crates/oxc_linter/src/rules/import/no_unused_modules.rs

@@ -1,42 +1,122 @@
 use oxc_diagnostics::{
-    miette::{self, Diagnostic},
+    miette::{self, diagnostic, Diagnostic},
     thiserror::Error,
 };
 use oxc_macros::declare_oxc_lint;
-use oxc_span::{CompactStr, Span};
+use oxc_span::Span;
 
 use crate::{context::LintContext, rule::Rule};
 
 #[derive(Debug, Error, Diagnostic)]
-#[error("eslint-plugin-import(namespace): ")]
-#[diagnostic(severity(warning), help(""))]
-struct NoUnusedModulesDiagnostic(CompactStr, #[label] pub Span);
+enum NoUnusedModulesDiagnostic {
+    #[error("eslint-plugin-import(no-unused-modules): No exports found")]
+    #[diagnostic(severity(warning))]
+    NoExportsFound(#[label] Span),
+}
 
-/// <https://github.com/import-js/eslint-plugin-import/blob/main/docs/rules/namespace.md>
+/// <https://github.com/import-js/eslint-plugin-import/blob/main/docs/rules/no-unused-modules.md>
 #[derive(Debug, Default, Clone)]
-pub struct NoUnusedModules;
+pub struct NoUnusedModules {
+    missing_exports: bool,
+    unused_exports: bool,
+}
 
 declare_oxc_lint!(
     /// ### What it does
-    /// TODO
+    ///
+    /// Reports:
+    /// * modules without any exports
+    /// * individual exports not being statically imported or requireed from other modules in the same project
+    /// * dynamic imports are supported if argument is a literal string
+    ///
     NoUnusedModules,
     nursery
 );
 
 impl Rule for NoUnusedModules {
-    fn run_once(&self, _ctx: &LintContext<'_>) {}
+    fn from_configuration(value: serde_json::Value) -> Self {
+        Self {
+            missing_exports: value
+                .get("missingExports")
+                .and_then(serde_json::Value::as_bool)
+                .unwrap_or(false),
+            unused_exports: value
+                .get("unusedExports")
+                .and_then(serde_json::Value::as_bool)
+                .unwrap_or(false),
+        }
+    }
+
+    fn run_once(&self, ctx: &LintContext<'_>) {
+        let module_record = ctx.semantic().module_record();
+        if self.missing_exports && module_record.local_export_entries.is_empty() {
+            ctx.diagnostic(NoUnusedModulesDiagnostic::NoExportsFound(Span::new(0, 0)));
+        }
+        if self.unused_exports {
+            // TODO: implement unused exports
+        }
+    }
 }
 
 #[test]
 fn test() {
-    // use crate::tester::Tester;
+    use crate::tester::Tester;
+    use serde_json::json;
+
+    let missing_exports_options = json!({
+      "missingExports": true,
+    });
+
+    let pass = vec![
+        ("export default function noOptions() {}", None),
+        ("export default () => 1", Some(missing_exports_options.clone())),
+        ("const a = 1; export { a }", Some(missing_exports_options.clone())),
+        ("function a() { return true }; export { a }", Some(missing_exports_options.clone())),
+        ("const a = 1; const b = 2; export { a, b }", Some(missing_exports_options.clone())),
+        ("const a = 1; export default a", Some(missing_exports_options.clone())),
+        ("export class Foo {}", Some(missing_exports_options.clone())),
+        ("export const [foobar] = [];", Some(missing_exports_options.clone())),
+        ("export const [foobar] = foobarFactory();", Some(missing_exports_options.clone())),
+        (
+            "export default function NewComponent () {
+            return 'I am new component'
+          }",
+            Some(missing_exports_options.clone()),
+        ),
+        (
+            "export default function NewComponent () {
+            return 'I am new component'
+          }",
+            Some(missing_exports_options.clone()),
+        ),
+    ];
+
+    let fail = vec![
+        ("const a = 1", Some(missing_exports_options.clone())),
+        ("/* const a = 1 */", Some(missing_exports_options.clone())),
+    ];
+
+    Tester::new(NoUnusedModules::NAME, pass, fail)
+        .change_rule_path("missing-exports.js")
+        .with_import_plugin(true)
+        .test_and_snapshot();
+
+    // TODO: support unused exports
+    // let unused_exports_options = json!({
+    //   "unusedExports": true,
+    //   "src": ["./no-unused-modules/**/*.js"],
+    //   "ignoreExports": ["./no-unused-modules/*ignored*.js"],
+    // });
 
-    // let pass = vec![];
+    // let pass = vec![
+    //     ("export default function noOptions() {}", None),
+    //     ("export default () => 1", Some(unused_exports_options)),
+    // ];
 
     // let fail = vec![];
 
     // Tester::new(NoUnusedModules::NAME, pass, fail)
-    // .change_rule_path("index.js")
-    // .with_import_plugin(true)
-    // .test_and_snapshot();
+    //     .change_rule_path("unused-exports.js")
+    //     .with_import_plugin(true)
+    //     .test_and_snapshot();
 }

crates/oxc_linter/src/snapshots/no_unused_modules.snap

@@ -0,0 +1,15 @@
+---
+source: crates/oxc_linter/src/tester.rs
+expression: no_unused_modules
+---
+  ⚠ eslint-plugin-import(no-unused-modules): No exports found
+   ╭─[missing-exports.js:1:1]
+ 1 │ const a = 1
+   · ▲
+   ╰────
+
+  ⚠ eslint-plugin-import(no-unused-modules): No exports found
+   ╭─[missing-exports.js:1:1]
+ 1 │ /* const a = 1 */
+   · ▲
+   ╰────