feat(testlab): add TestLab.writeJsonFile

packages/testlab/src/__tests__/integration/test-sandbox.integration.ts

@@ -3,9 +3,9 @@
 // This file is licensed under the MIT License.
 // License text available at https://opensource.org/licenses/MIT
 
-import {TestSandbox, expect} from '../..';
+import {pathExists, readFile, remove, writeJSON} from 'fs-extra';
 import {resolve} from 'path';
-import {remove, pathExists, readFile, writeJSON} from 'fs-extra';
+import {expect, TestSandbox} from '../..';
 
 const FIXTURES = resolve(__dirname, '../../../fixtures');
 
@@ -65,6 +65,14 @@ describe('TestSandbox integration tests', () => {
     expect(fileContents.pop()).to.equal(sourceMapString);
   });
 
+  it('creates a JSON file in the sandbox', async () => {
+    await sandbox.writeJsonFile('data.json', {key: 'value'});
+    const fullPath = resolve(path, 'data.json');
+    expect(await pathExists(fullPath)).to.be.True();
+    const content = await readFile(fullPath, 'utf-8');
+    expect(content).to.equal('{\n  "key": "value"\n}\n');
+  });
+
   it('resets the sandbox', async () => {
     const file = 'test.js';
     const resolvedFile = resolve(__dirname, '../fixtures/test.js');

packages/testlab/src/test-sandbox.ts

@@ -3,16 +3,17 @@
 // This file is licensed under the MIT License.
 // License text available at https://opensource.org/licenses/MIT
 
-import {resolve, parse} from 'path';
 import {
+  appendFile,
   copy,
-  ensureDirSync,
   emptyDir,
-  remove,
   ensureDir,
+  ensureDirSync,
   pathExists,
-  appendFile,
+  remove,
+  writeJson,
 } from 'fs-extra';
+import {parse, resolve} from 'path';
 
 /**
  * TestSandbox class provides a convenient way to get a reference to a
@@ -105,4 +106,17 @@ export class TestSandbox {
       await appendFile(dest, `\n//# sourceMappingURL=${srcMap}`);
     }
   }
+
+  /**
+   * Creates a new file and writes the given data serialized as JSON.
+   *
+   * @param dest - Destination filename, optionally including a relative path.
+   * @param data - The data to write.
+   */
+  async writeJsonFile(dest: string, data: unknown): Promise<void> {
+    dest = resolve(this.path, dest);
+    const destDir = parse(dest).dir;
+    await ensureDir(destDir);
+    return writeJson(dest, data, {spaces: 2});
+  }
 }