feat: add ignoreTypes option to define-flow-type rules

src/rules/defineFlowType.js

@@ -1,8 +1,23 @@
-const schema = [];
+const schema = [
+  {
+    properties: {
+      ignoreTypes: {
+        items: {
+          type: 'string',
+        },
+        type: 'array',
+      },
+    },
+    type: 'object',
+  },
+];
 
 const create = (context) => {
   let globalScope;
 
+  const [firstOption] = context.options;
+  const ignoreTypes = firstOption ? firstOption.ignoreTypes : [];
+
   // do nearly the same thing that eslint does for config globals
   // https://github.com/eslint/eslint/blob/v2.0.0/lib/eslint.js#L118-L194
   const makeDefined = (ident) => {
@@ -12,6 +27,10 @@ const create = (context) => {
     for (ii = globalScope.through.length - 1; ii >= 0; ii--) {
       const ref = globalScope.through[ii];
 
+      if (ignoreTypes.includes(ident.name)) {
+        return;
+      }
+
       if (ref.identifier.name === ident.name) {
         // use "__defineGeneric" since we don't have a reference to "escope.Variable"
 

tests/rules/assertions/defineFlowType.js

@@ -2,6 +2,7 @@ import {
   RuleTester,
 } from 'eslint';
 import noUndefRule from 'eslint/lib/rules/no-undef';
+import defineFlowType from '../../../src/rules/defineFlowType';
 
 const VALID_WITH_DEFINE_FLOW_TYPE = [
   {
@@ -146,6 +147,26 @@ type Foo = $ReadOnly<{}>`,
       },
     },
   },
+
+  /**
+   * There is unobvious behavior.
+   * We used Foo type and it became global variable.
+   * noUndefRule will not pay attention to Foo variable with defineFlowType.
+   * It can be fixed with ignoreTypes option
+ */
+  {
+    code: `
+type A = {foo: Foo};
+
+Foo()
+`,
+
+    // There are two errors one for type another for global var
+    errors: [
+      '\'Foo\' is not defined.',
+      '\'Foo\' is not defined.',
+    ],
+  },
 ];
 
 const ALWAYS_INVALID = [
@@ -221,6 +242,32 @@ const ALWAYS_VALID = [
   });
 }
 
+{
+  const ruleTester = new RuleTester({
+    parser: require.resolve('babel-eslint'),
+    rules: {
+      'define-flow-type': [1, {ignoreTypes: ['Foo']}],
+    },
+  });
+
+  ruleTester.defineRule('define-flow-type', defineFlowType);
+  ruleTester.run('no-undef must trigger an error when define-flow-type is used with ignoreTypes option', noUndefRule, {
+    invalid: [
+      {
+        code: `
+type A = {foo: Foo};
+Foo();
+`,
+        errors: [
+          '\'Foo\' is not defined.',
+          '\'Foo\' is not defined.',
+        ],
+      },
+    ],
+    valid: [],
+  });
+}
+
 export default {
   invalid: [],
   valid: [