test(eslint): create eslint test fixtures (#32396)

Author: michaelfaith

fixtures/eslint/.eslintrc.json renamed to fixtures/eslint-v6/.eslintrc.json

@@ -1,15 +1,14 @@
 {
   "root": true,
+  "extends": ["plugin:react-hooks/recommended-legacy"],
   "parserOptions": {
-    "ecmaVersion": 8,
+    "ecmaVersion": 2020,
     "sourceType": "module",
     "ecmaFeatures": {
       "jsx": true
     }
   },
-  "plugins": ["react-hooks"],
   "rules": {
-    "react-hooks/rules-of-hooks": 2,
-    "react-hooks/exhaustive-deps": 2
+    "react-hooks/exhaustive-deps": "error"
   }
 }

fixtures/eslint-v6/README.md

@@ -0,0 +1,12 @@
+# ESLint v6 Fixture
+
+This fixture allows us to test e2e functionality for `eslint-plugin-react-hooks` with eslint version 6.
+
+Run the following to test.
+
+```sh
+cd fixtures/eslint-v6
+yarn
+yarn build
+yarn lint
+```

fixtures/eslint-v6/build.mjs

@@ -0,0 +1,5 @@
+#!/usr/bin/env node
+
+import {exec} from 'node:child_process';
+
+exec('cd ../.. && yarn build -r stable eslint-plugin-react-hooks');

fixtures/eslint-v6/index.js

@@ -0,0 +1,143 @@
+/**
+ * Exhaustive Deps
+ */
+// Valid because dependencies are declared correctly
+function Comment({comment, commentSource}) {
+  const currentUserID = comment.viewer.id;
+  const environment = RelayEnvironment.forUser(currentUserID);
+  const commentID = nullthrows(comment.id);
+  useEffect(() => {
+    const subscription = SubscriptionCounter.subscribeOnce(
+      `StoreSubscription_${commentID}`,
+      () =>
+        StoreSubscription.subscribe(
+          environment,
+          {
+            comment_id: commentID,
+          },
+          currentUserID,
+          commentSource
+        )
+    );
+    return () => subscription.dispose();
+  }, [commentID, commentSource, currentUserID, environment]);
+}
+
+// Valid because no dependencies
+function UseEffectWithNoDependencies() {
+  const local = {};
+  useEffect(() => {
+    console.log(local);
+  });
+}
+function UseEffectWithEmptyDependencies() {
+  useEffect(() => {
+    const local = {};
+    console.log(local);
+  }, []);
+}
+
+// OK because `props` wasn't defined.
+function ComponentWithNoPropsDefined() {
+  useEffect(() => {
+    console.log(props.foo);
+  }, []);
+}
+
+// Valid because props are declared as a dependency
+function ComponentWithPropsDeclaredAsDep({foo}) {
+  useEffect(() => {
+    console.log(foo.length);
+    console.log(foo.slice(0));
+  }, [foo]);
+}
+
+// Valid because individual props are declared as dependencies
+function ComponentWithIndividualPropsDeclaredAsDeps(props) {
+  useEffect(() => {
+    console.log(props.foo);
+    console.log(props.bar);
+  }, [props.bar, props.foo]);
+}
+
+// Invalid because neither props or props.foo are declared as dependencies
+function ComponentWithoutDeclaringPropAsDep(props) {
+  useEffect(() => {
+    console.log(props.foo);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
+  useCallback(() => {
+    console.log(props.foo);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
+  useMemo(() => {
+    console.log(props.foo);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
+  React.useEffect(() => {
+    console.log(props.foo);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
+  React.useCallback(() => {
+    console.log(props.foo);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
+  React.useMemo(() => {
+    console.log(props.foo);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
+  React.notReactiveHook(() => {
+    console.log(props.foo);
+  }, []); // This one isn't a violation
+}
+
+/**
+ * Rules of Hooks
+ */
+// Valid because functions can call functions.
+function normalFunctionWithConditionalFunction() {
+  if (cond) {
+    doSomething();
+  }
+}
+
+// Valid because hooks can call hooks.
+function useHook() {
+  useState();
+}
+const whatever = function useHook() {
+  useState();
+};
+const useHook1 = () => {
+  useState();
+};
+let useHook2 = () => useState();
+useHook2 = () => {
+  useState();
+};
+
+// Invalid because hooks can't be called in conditionals.
+function ComponentWithConditionalHook() {
+  if (cond) {
+    // eslint-disable-next-line react-hooks/rules-of-hooks
+    useConditionalHook();
+  }
+}
+
+// Invalid because hooks can't be called in loops.
+function useHookInLoops() {
+  while (a) {
+    // eslint-disable-next-line react-hooks/rules-of-hooks
+    useHook1();
+    if (b) return;
+    // eslint-disable-next-line react-hooks/rules-of-hooks
+    useHook2();
+  }
+  while (c) {
+    // eslint-disable-next-line react-hooks/rules-of-hooks
+    useHook3();
+    if (d) return;
+    // eslint-disable-next-line react-hooks/rules-of-hooks
+    useHook4();
+  }
+}

fixtures/eslint-v6/package.json

@@ -0,0 +1,12 @@
+{
+  "private": true,
+  "name": "eslint-v6",
+  "dependencies": {
+    "eslint": "^6",
+    "eslint-plugin-react-hooks": "link:../../build/node_modules/eslint-plugin-react-hooks"
+  },
+  "scripts": {
+    "build": "node build.mjs && yarn",
+    "lint": "eslint index.js --report-unused-disable-directives"
+  }
+}