From 84cc0239677e62442a3395a8fe7c43884647dbfc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Zeutzheim?= <github@bzeutzheim.de>
Date: Sat, 5 Dec 2020 14:11:09 +0100
Subject: [PATCH] feat(eslint-plugin): [consistent-type-imports] Add mixed mode
 option

This ads a new mode called "type-imports-mixed" for consistent-type-imports rule which will only trigger, if all imports of an import declaration are type only imports.

References #2769
---
 .../src/rules/consistent-type-imports.ts      | 11 ++++--
 .../rules/consistent-type-imports.test.ts     | 37 +++++++++++++++++++
 2 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/packages/eslint-plugin/src/rules/consistent-type-imports.ts b/packages/eslint-plugin/src/rules/consistent-type-imports.ts
index c4cb6586a00..eb687642ed3 100644
--- a/packages/eslint-plugin/src/rules/consistent-type-imports.ts
+++ b/packages/eslint-plugin/src/rules/consistent-type-imports.ts
@@ -6,7 +6,7 @@ import {
 } from '@typescript-eslint/experimental-utils';
 import * as util from '../util';
 
-type Prefer = 'type-imports' | 'no-type-imports';
+type Prefer = 'type-imports' | 'no-type-imports' | 'type-imports-mixed';
 
 type Options = [
   {
@@ -67,7 +67,7 @@ export default util.createRule<Options, MessageIds>({
         type: 'object',
         properties: {
           prefer: {
-            enum: ['type-imports', 'no-type-imports'],
+            enum: ['type-imports', 'no-type-imports', 'type-imports-mixed'],
           },
           disallowTypeAnnotations: {
             type: 'boolean',
@@ -94,7 +94,7 @@ export default util.createRule<Options, MessageIds>({
     const sourceImportsMap: { [key: string]: SourceImports } = {};
 
     return {
-      ...(prefer === 'type-imports'
+      ...(prefer !== 'no-type-imports'
         ? {
             // prefer type imports
             ImportDeclaration(node: TSESTree.ImportDeclaration): void {
@@ -157,7 +157,10 @@ export default util.createRule<Options, MessageIds>({
                 }
               }
 
-              if (typeSpecifiers.length) {
+              if (
+                typeSpecifiers.length &&
+                (prefer === 'type-imports' || valueSpecifiers.length === 0)
+              ) {
                 sourceImports.reportValueImports.push({
                   node,
                   typeSpecifiers,
diff --git a/packages/eslint-plugin/tests/rules/consistent-type-imports.test.ts b/packages/eslint-plugin/tests/rules/consistent-type-imports.test.ts
index 8818225a024..4b2543c4cb1 100644
--- a/packages/eslint-plugin/tests/rules/consistent-type-imports.test.ts
+++ b/packages/eslint-plugin/tests/rules/consistent-type-imports.test.ts
@@ -109,6 +109,23 @@ ruleTester.run('consistent-type-imports', rule, {
       `,
       options: [{ prefer: 'no-type-imports' }],
     },
+    // type-imports-mixed
+    {
+      code: `
+        import { A, B } from 'foo';
+        const foo: A = B();
+      `,
+      options: [{ prefer: 'type-imports-mixed' }],
+    },
+    {
+      code: `
+        import type A from 'foo';
+        import B from 'foo';
+        let foo: A;
+        let bar = B;
+      `,
+      options: [{ prefer: 'type-imports-mixed' }],
+    },
     // exports
     `
       import Type from 'foo';
@@ -1215,5 +1232,25 @@ const a: Default = '';
         },
       ],
     },
+    {
+      code: `
+import { A, B } from 'foo';
+let foo: A;
+let bar: B;
+      `,
+      output: `
+import type { A, B } from 'foo';
+let foo: A;
+let bar: B;
+      `,
+      options: [{ prefer: 'type-imports-mixed' }],
+      errors: [
+        {
+          messageId: 'typeOverValue',
+          line: 2,
+          column: 1,
+        },
+      ],
+    },
   ],
 });