feat: add support for expectTypeOf to expect-expect (#386)

Author: mrmckeb

README.md

@@ -108,6 +108,22 @@ export default [
 ];
 ```
 
+#### Enabling with type-testing
+
+Vitest ships with an optional [type-testing feature](https://vitest.dev/guide/testing-types), which is disabled by default.
+
+If you're using this feature, you should also enabled `typecheck` in the settings for this plugin. This ensures that rules like [expect-expect](docs/rules/expect-expect.md) account for type-related assertions in tests.
+
+```json
+{
+  "extends": ["plugin:vitest/recommended"],
+  "settings" :{
+    "vitest": {
+      "typecheck": true,
+    }
+  }
+}
+```
 
 ### Rules
 

docs/rules/expect-expect.md

@@ -28,6 +28,10 @@ test('myLogic', () => {
 })
 ```
 
+## Type-testing
+
+If you're using Vitest's [type-testing feature](https://vitest.dev/guide/testing-types) and have tests that only contain `expectTypeOf`, you will need to enable `typecheck` in this plugin's settings: [Enabling type-testing](../../README.md#enabling-with-type-testing).
+
 ## Options
 
 ### `assertFunctionNames`

src/rules/expect-expect.ts

@@ -1,5 +1,6 @@
 import { AST_NODE_TYPES, TSESTree } from '@typescript-eslint/utils'
 import { createEslintRule, getNodeName, isSupportedAccessor } from '../utils'
+import { parsePluginSettings } from '../utils/parsePluginSettings'
 import { getTestCallExpressionsFromDeclaredVariables, isTypeOfVitestFnCall } from '../utils/parseVitestFnCall'
 
 export const RULE_NAME = 'expect-expect'
@@ -62,6 +63,9 @@ export default createEslintRule<Options, MESSAGE_ID>({
     defaultOptions: [{ assertFunctionNames: ['expect'], additionalTestBlockFunctions: [] }],
     create(context, [{ assertFunctionNames = ['expect'], additionalTestBlockFunctions = [] }]) {
 		const unchecked: TSESTree.CallExpression[] = []
+		const settings = parsePluginSettings(context.settings)
+
+		if (settings.typecheck) assertFunctionNames.push('expectTypeOf')
 
 		function checkCallExpression(nodes: TSESTree.Node[]) {
 			for (const node of nodes) {
@@ -82,12 +86,11 @@ export default createEslintRule<Options, MESSAGE_ID>({
 		}
 
         return {
-			CallExpression(node) {		
-				if (node?.callee?.type === AST_NODE_TYPES.MemberExpression && node.callee.property.type === AST_NODE_TYPES.Identifier && node.callee.property.name === 'skip') 
+			CallExpression(node) {
+				if (node?.callee?.type === AST_NODE_TYPES.MemberExpression && node.callee.property.type === AST_NODE_TYPES.Identifier && node.callee.property.name === 'skip')
 					return
-    
-					const name = getNodeName(node) ?? ''
 
+					const name = getNodeName(node) ?? ''
 
 				if (isTypeOfVitestFnCall(node, context, ['test']) || additionalTestBlockFunctions.includes(name)) {
 					if (node.callee.type === AST_NODE_TYPES.MemberExpression && isSupportedAccessor(node.callee.property, 'todo')) return

src/utils/parsePluginSettings.ts

@@ -0,0 +1,20 @@
+import type { SharedConfigurationSettings } from '@typescript-eslint/utils/dist/ts-eslint'
+
+interface PluginSettings {
+    typecheck: boolean;
+}
+
+const DEFAULTS: PluginSettings = {
+    typecheck: false
+}
+
+export function parsePluginSettings(settings: SharedConfigurationSettings): PluginSettings {
+    const pluginSettings = typeof settings.vitest !== 'object' || settings.vitest === null
+        ? {}
+        : settings.vitest
+
+    return {
+        ...DEFAULTS,
+        ...pluginSettings
+    }
+}

tests/expect-expect.test.ts

@@ -155,6 +155,14 @@ ruleTester.run(RULE_NAME, rule, {
 			`,
 			options: [{ assertFunctionNames: ['tester.foo.bar.expect'] }],
 			parserOptions: { sourceType: 'module' }
+		 },
+		 {
+			code: `
+			it("should pass with 'typecheck' enabled", () => {
+				expectTypeOf({ a: 1 }).toEqualTypeOf<{ a: number }>()
+			});
+			`,
+			settings: { vitest: { typecheck: true } }
 		 }
 	],
 	invalid: [
@@ -304,6 +312,19 @@ ruleTester.run(RULE_NAME, rule, {
 				type: AST_NODE_TYPES.Identifier
 			}
 			]
+		 },
+		 {
+			code: `
+			it("should fail without 'typecheck' enabled", () => {
+				expectTypeOf({ a: 1 }).toEqualTypeOf<{ a: number }>()
+			});
+			`,
+			errors: [
+				{
+					messageId: 'noAssertions',
+					type: AST_NODE_TYPES.Identifier
+				}
+			]
 		 }
 	]
 })