Correctly lint test helpers (#1281)

Our test helper modules have been covered by ESLint as though they were
production code. This resulted in misleading coverage statistics and
various erronous lint errors (which we've handled by disabling rules in
affected files).

The ESLint configuration has been updated to consider any modules under
a `tests` directory to be test helpers.

This helps reduce the scope of #1116

.eslintrc.js

@@ -11,9 +11,23 @@ module.exports = {
   ],
   overrides: [
     {
-      files: ['*.test.ts', '*.test.js'],
+      files: ['*.test.{ts,js}', '**/tests/**/*.{ts,js}'],
       extends: ['@metamask/eslint-config-jest'],
     },
+    {
+      // These files are test helpers, not tests. We still use the Jest ESLint
+      // config here to ensure that ESLint expects a test-like environment, but
+      // various rules meant just to apply to tests have been disabled.
+      files: ['**/tests/**/*.{ts,js}', '!*.test.{ts,js}'],
+      rules: {
+        'jest/no-export': 'off',
+        'jest/require-top-level-describe': 'off',
+        'jest/no-if': 'off',
+        'jest/no-test-return-statement': 'off',
+        // TODO: Re-enable this rule; we can accomodate this even in our test helpers
+        'jest/expect-expect': 'off',
+      },
+    },
     {
       files: ['*.js'],
       parserOptions: {

packages/network-controller/tests/provider-api-tests/block-hash-in-response.ts

@@ -1,4 +1,3 @@
-/* eslint-disable no-loop-func */
 import {
   ProviderType,
   waitForNextBlockTracker,

packages/network-controller/tests/provider-api-tests/block-param.ts

@@ -1,4 +1,3 @@
-/* eslint-disable no-loop-func */
 import {
   buildMockParams,
   buildRequestWithReplacedBlockParam,

packages/network-controller/tests/provider-api-tests/no-block-param.ts

@@ -1,5 +1,3 @@
-/* eslint-disable no-loop-func */
-
 import {
   MockCommunications,
   ProviderType,

packages/network-controller/tests/provider-api-tests/shared-tests.ts

@@ -1,5 +1,3 @@
-/* eslint-disable jest/require-top-level-describe, jest/no-export, jest/no-identical-title, jest/no-if */
-
 import { NetworkType } from '@metamask/controller-utils';
 import { testsForRpcMethodsThatCheckForBlockHashInResponse } from './block-hash-in-response';
 import { testsForRpcMethodSupportingBlockParam } from './block-param';

tests/helpers.ts

@@ -6,13 +6,13 @@ const originalSetTimeout = global.setTimeout;
  * times) until it returns a value.
  *
  * @param expectedValue - The value that the function should return.
- * @param test - The function to call.
+ * @param operation - The function to call.
  * @returns A promise that either resolves to a successful result as soon as it
  * returns the expected value, or a failure result if that never happens.
  */
 export async function waitForResult(
   expectedValue: any,
-  test: () => any,
+  operation: () => any,
 ): Promise<{ pass: boolean; lastActualValue?: any }> {
   const approximateRunTime = 10000;
   const intervalBetweenRetries = 25;
@@ -22,7 +22,7 @@ export async function waitForResult(
   let lastActualValue: any;
 
   while (numIterations < maxNumIterations) {
-    const actualValue = test();
+    const actualValue = operation();
     if (actualValue === expectedValue) {
       return { pass: true };
     }