Revert "[ESLint] Forbid top-level use*() calls (facebook#16455)"

This reverts commit 96eb703.

packages/eslint-plugin-react-hooks/__tests__/ESLintRulesOfHooks-test.js

@@ -19,17 +19,8 @@ ESLintTester.setDefaultConfig({
   },
 });
 
-// ***************************************************
-// For easier local testing, you can add to any case:
-// {
-//   skip: true,
-//   --or--
-//   only: true,
-//   ...
-// }
-// ***************************************************
-
-const tests = {
+const eslintTester = new ESLintTester();
+eslintTester.run('react-hooks', ReactHooksESLintRule, {
   valid: [
     `
       // Valid because components can use hooks.
@@ -232,20 +223,21 @@ const tests = {
       (class {i() { useState(); }});
     `,
     `
-      // Valid because they're not matching use[A-Z].
-      fooState();
+      // Currently valid although we *could* consider these invalid.
+      // It doesn't make a lot of difference because it would crash early.
       use();
       _use();
+      useState();
       _useState();
+      use42();
+      useHook();
       use_hook();
+      React.useState();
     `,
     `
-      // This is grey area.
-      // Currently it's valid (although React.useCallback would fail here).
-      // We could also get stricter and disallow it, just like we did
-      // with non-namespace use*() top-level calls.
-      const History = require('history-2.1.2');
-      const browserHistory = History.useBasename(History.createHistory)({
+      // Regression test for the popular "history" library
+      const {createHistory, useBasename} = require('history-2.1.2');
+      const browserHistory = useBasename(createHistory)({
         basename: '/',
       });
     `,
@@ -677,63 +669,8 @@ const tests = {
         conditionalError('useState'),
       ],
     },
-    {
-      code: `
-        // Invalid because it's dangerous and might not warn otherwise.
-        // This *must* be invalid.
-        function useHook({ bar }) {
-          let foo1 = bar && useState();
-          let foo2 = bar || useState();
-          let foo3 = bar ?? useState();
-        }
-      `,
-      errors: [
-        conditionalError('useState'),
-        conditionalError('useState'),
-        // TODO: ideally this *should* warn, but ESLint
-        // doesn't plan full support for ?? until it advances.
-        // conditionalError('useState'),
-      ],
-    },
-    {
-      code: `
-        // Invalid because it's dangerous.
-        // Normally, this would crash, but not if you use inline requires.
-        // This *must* be invalid.
-        // It's expected to have some false positives, but arguably
-        // they are confusing anyway due to the use*() convention
-        // already being associated with Hooks.
-        useState();
-        if (foo) {
-          const foo = React.useCallback(() => {});
-        }
-        useCustomHook();
-      `,
-      errors: [
-        topLevelError('useState'),
-        topLevelError('React.useCallback'),
-        topLevelError('useCustomHook'),
-      ],
-    },
-    {
-      code: `
-        // Technically this is a false positive.
-        // We *could* make it valid (and it used to be).
-        //
-        // However, top-level Hook-like calls can be very dangerous
-        // in environments with inline requires because they can mask
-        // the runtime error by accident.
-        // So we prefer to disallow it despite the false positive.
-
-        const {createHistory, useBasename} = require('history-2.1.2');
-        const browserHistory = useBasename(createHistory)({
-          basename: '/',
-        });
-      `,
-      errors: [topLevelError('useBasename')],
-    },
   ],
-};
+});
 
 function conditionalError(hook, hasPreviousFinalizer = false) {
   return {
@@ -771,42 +708,3 @@ function genericError(hook) {
       'Hook function.',
   };
 }
-
-function topLevelError(hook) {
-  return {
-    message:
-      `React Hook "${hook}" cannot be called at the top level. React Hooks ` +
-      'must be called in a React function component or a custom React ' +
-      'Hook function.',
-  };
-}
-
-// For easier local testing
-if (!process.env.CI) {
-  let only = [];
-  let skipped = [];
-  [...tests.valid, ...tests.invalid].forEach(t => {
-    if (t.skip) {
-      delete t.skip;
-      skipped.push(t);
-    }
-    if (t.only) {
-      delete t.only;
-      only.push(t);
-    }
-  });
-  const predicate = t => {
-    if (only.length > 0) {
-      return only.indexOf(t) !== -1;
-    }
-    if (skipped.length > 0) {
-      return skipped.indexOf(t) === -1;
-    }
-    return true;
-  };
-  tests.valid = tests.valid.filter(predicate);
-  tests.invalid = tests.invalid.filter(predicate);
-}
-
-const eslintTester = new ESLintTester();
-eslintTester.run('react-hooks', ReactHooksESLintRule, tests);

packages/eslint-plugin-react-hooks/src/RulesOfHooks.js

@@ -432,13 +432,9 @@ export default {
                 'React Hook function.';
               context.report({node: hook, message});
             } else if (codePathNode.type === 'Program') {
+              // For now, ignore if it's in top level scope.
               // We could warn here but there are false positives related
               // configuring libraries like `history`.
-              const message =
-                `React Hook "${context.getSource(hook)}" cannot be called ` +
-                'at the top level. React Hooks must be called in a ' +
-                'React function component or a custom React Hook function.';
-              context.report({node: hook, message});
             } else {
               // Assume in all other cases the user called a hook in some
               // random function callback. This should usually be true for