chore(prefer-spy-on): convert to typescript (#326)

Author: G-Rath

src/rules/__tests__/prefer-spy-on.test.js renamed to src/rules/__tests__/prefer-spy-on.test.ts

@@ -1,7 +1,10 @@
-import { RuleTester } from 'eslint';
+import {
+  AST_NODE_TYPES,
+  TSESLint,
+} from '@typescript-eslint/experimental-utils';
 import rule from '../prefer-spy-on';
 
-const ruleTester = new RuleTester({
+const ruleTester = new TSESLint.RuleTester({
   parserOptions: {
     ecmaVersion: 6,
   },
@@ -22,44 +25,84 @@ ruleTester.run('prefer-spy-on', rule, {
   invalid: [
     {
       code: 'obj.a = jest.fn(); const test = 10;',
-      errors: [{ messageId: 'useJestSpyOn', type: 'AssignmentExpression' }],
+      errors: [
+        {
+          messageId: 'useJestSpyOn',
+          type: AST_NODE_TYPES.AssignmentExpression,
+        },
+      ],
       output: "jest.spyOn(obj, 'a'); const test = 10;",
     },
     {
       code: "Date['now'] = jest['fn']()",
-      errors: [{ messageId: 'useJestSpyOn', type: 'AssignmentExpression' }],
+      errors: [
+        {
+          messageId: 'useJestSpyOn',
+          type: AST_NODE_TYPES.AssignmentExpression,
+        },
+      ],
       output: "jest.spyOn(Date, 'now')",
     },
     {
       code: 'window[`${name}`] = jest[`fn`]()',
-      errors: [{ messageId: 'useJestSpyOn', type: 'AssignmentExpression' }],
+      errors: [
+        {
+          messageId: 'useJestSpyOn',
+          type: AST_NODE_TYPES.AssignmentExpression,
+        },
+      ],
       output: 'jest.spyOn(window, `${name}`)',
     },
     {
       code: "obj['prop' + 1] = jest['fn']()",
-      errors: [{ messageId: 'useJestSpyOn', type: 'AssignmentExpression' }],
+      errors: [
+        {
+          messageId: 'useJestSpyOn',
+          type: AST_NODE_TYPES.AssignmentExpression,
+        },
+      ],
       output: "jest.spyOn(obj, 'prop' + 1)",
     },
     {
       code: 'obj.one.two = jest.fn(); const test = 10;',
-      errors: [{ messageId: 'useJestSpyOn', type: 'AssignmentExpression' }],
+      errors: [
+        {
+          messageId: 'useJestSpyOn',
+          type: AST_NODE_TYPES.AssignmentExpression,
+        },
+      ],
       output: "jest.spyOn(obj.one, 'two'); const test = 10;",
     },
     {
       code: 'obj.a = jest.fn(() => 10)',
-      errors: [{ messageId: 'useJestSpyOn', type: 'AssignmentExpression' }],
+      errors: [
+        {
+          messageId: 'useJestSpyOn',
+          type: AST_NODE_TYPES.AssignmentExpression,
+        },
+      ],
       output: "jest.spyOn(obj, 'a').mockImplementation(() => 10)",
     },
     {
       code:
         "obj.a.b = jest.fn(() => ({})).mockReturnValue('default').mockReturnValueOnce('first call'); test();",
-      errors: [{ messageId: 'useJestSpyOn', type: 'AssignmentExpression' }],
+      errors: [
+        {
+          messageId: 'useJestSpyOn',
+          type: AST_NODE_TYPES.AssignmentExpression,
+        },
+      ],
       output:
         "jest.spyOn(obj.a, 'b').mockImplementation(() => ({})).mockReturnValue('default').mockReturnValueOnce('first call'); test();",
     },
     {
       code: 'window.fetch = jest.fn(() => ({})).one.two().three().four',
-      errors: [{ messageId: 'useJestSpyOn', type: 'AssignmentExpression' }],
+      errors: [
+        {
+          messageId: 'useJestSpyOn',
+          type: AST_NODE_TYPES.AssignmentExpression,
+        },
+      ],
       output:
         "jest.spyOn(window, 'fetch').mockImplementation(() => ({})).one.two().three().four",
     },

src/rules/prefer-spy-on.js

@@ -0,0 +1,100 @@
+import {
+  AST_NODE_TYPES,
+  TSESTree,
+} from '@typescript-eslint/experimental-utils';
+import { createRule, getNodeName } from './tsUtils';
+
+const findNodeObject = (
+  node: TSESTree.CallExpression | TSESTree.MemberExpression,
+): TSESTree.LeftHandSideExpression | null => {
+  if ('object' in node) {
+    return node.object;
+  }
+
+  if (node.callee.type === AST_NODE_TYPES.MemberExpression) {
+    return node.callee.object;
+  }
+
+  return null;
+};
+
+const getJestFnCall = (node: TSESTree.Node): TSESTree.CallExpression | null => {
+  if (
+    node.type !== AST_NODE_TYPES.CallExpression &&
+    node.type !== AST_NODE_TYPES.MemberExpression
+  ) {
+    return null;
+  }
+
+  const obj = findNodeObject(node);
+
+  if (!obj) {
+    return null;
+  }
+
+  if (obj.type === AST_NODE_TYPES.Identifier) {
+    return node.type === AST_NODE_TYPES.CallExpression &&
+      getNodeName(node.callee) === 'jest.fn'
+      ? node
+      : null;
+  }
+
+  return getJestFnCall(obj);
+};
+
+export default createRule({
+  name: __filename,
+  meta: {
+    docs: {
+      category: 'Best Practices',
+      description: 'Suggest using `jest.spyOn()`',
+      recommended: false,
+    },
+    messages: {
+      useJestSpyOn: 'Use jest.spyOn() instead.',
+    },
+    fixable: 'code',
+    schema: [],
+    type: 'suggestion',
+  },
+  defaultOptions: [],
+  create(context) {
+    return {
+      AssignmentExpression(node) {
+        const { left, right } = node;
+
+        if (left.type !== AST_NODE_TYPES.MemberExpression) return;
+
+        const jestFnCall = getJestFnCall(right);
+
+        if (!jestFnCall) return;
+
+        context.report({
+          node,
+          messageId: 'useJestSpyOn',
+          fix(fixer) {
+            const leftPropQuote =
+              left.property.type === AST_NODE_TYPES.Identifier ? "'" : '';
+            const [arg] = jestFnCall.arguments;
+            const argSource = arg && context.getSourceCode().getText(arg);
+            const mockImplementation = argSource
+              ? `.mockImplementation(${argSource})`
+              : '';
+
+            return [
+              fixer.insertTextBefore(left, `jest.spyOn(`),
+              fixer.replaceTextRange(
+                [left.object.range[1], left.property.range[0]],
+                `, ${leftPropQuote}`,
+              ),
+              fixer.replaceTextRange(
+                [left.property.range[1], jestFnCall.range[1]],
+                `${leftPropQuote})${mockImplementation}`,
+              ),
+            ];
+          },
+        });
+      },
+    };
+  },
+});

src/rules/prefer-spy-on.ts

@@ -109,11 +109,6 @@ export const getNodeName = node => {
   switch (node && node.type) {
     case 'Identifier':
       return node.name;
-    case 'Literal':
-      return node.value;
-    case 'TemplateLiteral':
-      if (node.expressions.length === 0) return node.quasis[0].value.cooked;
-      break;
     case 'MemberExpression':
       return joinNames(getNodeName(node.object), getNodeName(node.property));
   }