Refactor out generateJestConfig flag logic to reduce duplication

docs/releases/4.0.x.md

@@ -27,7 +27,7 @@ We suggest reading through the following migration guides:
 
 Some noteworthy breaking changes:
 
-- Change to default snapshot options to {escapeString: false,
+- Changed default snapshot formatting options to {escapeString: false,
   printBasicPrototype: false} as outlined by
   [this blogpost](https://jestjs.io/blog/2022/04/25/jest-28#future) - Any
   snapshots tests will have to be updated with the new format, or you can

packages/modular-scripts/src/lint.ts

@@ -8,8 +8,7 @@ import getModularRoot from './utils/getModularRoot';
 import execAsync from './utils/execAsync';
 import { addFiles, getDiffedFiles, getStagedFiles } from './utils/gitActions';
 import * as logger from './utils/logger';
-import * as tmp from 'tmp';
-import { writeJSONSync } from 'fs-extra';
+import { generateJestConfig } from './test/utils';
 export interface LintOptions {
   all: boolean;
   fix: boolean;
@@ -55,21 +54,11 @@ async function lint(
     testPathIgnorePatterns: ['/node_modules/', '/dist/'],
   };
 
-  // Only used when running on Windows
-  const tempConfigPath = path.join(
-    tmp.dirSync().name,
-    'temp-jest-eslint-config.json',
-  );
-
-  // Windows: pass in configuration as a file as jest won't accept "" around the object and Windows doesn't accept JSON object {} passed directly
-  // Any other plaform pass config directly to command
-  let testArgs: string[];
-  if (process.platform === 'win32') {
-    writeJSONSync(tempConfigPath, jestEslintConfig);
-    testArgs = [...regexes, '--config', tempConfigPath];
-  } else {
-    testArgs = [...regexes, '--config', JSON.stringify(jestEslintConfig)];
-  }
+  const testArgs = [
+    ...regexes,
+    '--config',
+    generateJestConfig(jestEslintConfig),
+  ];
 
   const testBin = await resolveAsBin('jest-cli');
 

packages/modular-scripts/src/test/index.ts

@@ -9,12 +9,11 @@ import { getAllWorkspaces } from '../utils/getAllWorkspaces';
 import { getChangedWorkspaces } from '../utils/getChangedWorkspaces';
 import { resolveAsBin } from '../utils/resolveAsBin';
 import * as logger from '../utils/logger';
-import * as tmp from 'tmp';
 import type {
   WorkspaceContent,
   ModularWorkspacePackage,
 } from '@modular-scripts/modular-types';
-import { writeJSONSync } from 'fs-extra';
+import { generateJestConfig } from './utils';
 
 export interface TestOptions {
   ancestors: boolean;
@@ -89,26 +88,10 @@ async function test(
 
   // pass in jest configuration
   const { createJestConfig } = await import('./config');
-
-  // Only used when running on Windows
-  const tempConfigPath = path.join(tmp.dirSync().name, 'temp-jest-config.json');
-
-  // Windows: pass in configuration as a file as jest won't accept "" around the object and Windows doesn't accept JSON object {} passed directly
-  // Any other plaform pass config directly to command
-  if (process.platform === 'win32') {
-    writeJSONSync(
-      tempConfigPath,
-      createJestConfig({ reporters, testResultsProcessor }),
-    );
-    cleanArgv.push('--config', `${tempConfigPath}`);
-  } else {
-    cleanArgv.push(
-      '--config',
-      `${JSON.stringify(
-        createJestConfig({ reporters, testResultsProcessor }),
-      )}`,
-    );
-  }
+  cleanArgv.push(
+    '--config',
+    generateJestConfig(createJestConfig({ reporters, testResultsProcessor })),
+  );
 
   let resolvedEnv;
   try {

packages/modular-scripts/src/test/utils.ts

@@ -1,13 +1,14 @@
 import _rimraf from 'rimraf';
 import execa from 'execa';
-import fs from 'fs-extra';
+import fs, { writeJSONSync } from 'fs-extra';
 import path from 'path';
 import * as tmp from 'tmp';
 import { promisify } from 'util';
 
 import getModularRoot from '../utils/getModularRoot';
 import type { ModularPackageJson } from '@modular-scripts/modular-types';
 import { mkdirSync } from 'fs';
+import type { Config } from '@jest/types';
 
 const rimraf = promisify(_rimraf);
 
@@ -132,3 +133,23 @@ export function mockInstallTemplate(
     path.join(tempRepoNodeModules, templateName),
   );
 }
+
+/**
+ * Generates the Jest --config flag contents to pass when calling Jest based on config JSON provided
+ *
+ * - On Mac, it will provide a stringyfied version of the config JSON provided
+ *
+ * - On Windows, it will write the config JSON to a file in a temp directory and provde the path to pass
+ */
+export function generateJestConfig(jestConfig: Config.InitialOptions): string {
+  if (process.platform === 'win32') {
+    const tempConfigPath = path.join(
+      tmp.dirSync().name,
+      'temp-jest-config.json',
+    );
+    writeJSONSync(tempConfigPath, jestConfig);
+    return `${tempConfigPath}`;
+  } else {
+    return `${JSON.stringify(jestConfig)}`;
+  }
+}