add snapshot tests for generated icon

Author: gsabran

__image_snapshots__/test-js-binary-plist-1-snap.png

@@ -55,6 +55,7 @@
 	},
 	"devDependencies": {
 		"ava": "^6.1.1",
+		"jest-image-snapshot": "^6.5.1",
 		"xo": "^0.56.0"
 	}
 }

__image_snapshots__/test-js-main-1-snap.png

@@ -4,9 +4,56 @@ import {fileURLToPath} from 'node:url';
 import test from 'ava';
 import {execa} from 'execa';
 import {temporaryDirectory} from 'tempy';
+import jestImageSnapshot from 'jest-image-snapshot';
+import { spawnSync } from 'node:child_process';
+const { configureToMatchImageSnapshot } = jestImageSnapshot;
 
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
+/** Validate that the icon for the DMG matches the snapshot (with a small tolerance to avoid flakiness) */
+const assertVolumeIconMatchesSnapshot = (t, dmgPath) => {
+	// Mount the DMG and extract the volume icon
+	const existingVolumes = new Set(fs.readdirSync('/Volumes'));
+	spawnSync('hdiutil', ['mount', dmgPath]);
+	const volumes = new Set(fs.readdirSync('/Volumes'));
+	const mountLocation = [...volumes].find(x => !existingVolumes.has(x));
+	t.truthy(mountLocation);
+	const dmgIconPath = path.join('/Volumes', mountLocation, '.VolumeIcon.icns')
+	const dirPath = path.dirname(dmgPath);
+	const iconPath = path.join(dirPath, 'VolumeIcon.icns');
+	fs.copyFileSync(dmgIconPath, iconPath);
+	spawnSync('hdiutil', ['unmount', path.join('/Volumes', mountLocation)]);
+	const pngPath = path.join(dirPath, 'VolumeIcon.png');
+	spawnSync('sips', ['-s', 'format', 'png', iconPath, '--out', pngPath]);
+
+	// Compare the extracted icon to the snapshot
+	const image = fs.readFileSync(pngPath);
+
+	// Create a Jest-like context for jest-image-snapshot
+	const jestContext = {
+		testPath: fileURLToPath(import.meta.url),
+		currentTestName: t.title,
+		_counters: new Map(),
+		snapshotState: {
+			_counters: new Map(),
+			_updateSnapshot: process.env.UPDATE_SNAPSHOT === 'true' ? 'all' : 'new',
+			updated: 0,
+			added: 0
+		}
+	};
+
+	const result = configureToMatchImageSnapshot({
+	failureThreshold: 0.01,
+	failureThresholdType: 'percent',
+	}).call(jestContext, image)
+
+	if (result.pass) {
+		t.pass();
+	} else {
+		t.fail(result.message());
+	}
+}
+
 test('main', async t => {
 	const cwd = temporaryDirectory();
 
@@ -18,8 +65,10 @@ test('main', async t => {
 			throw error;
 		}
 	}
+	const dmgPath = path.join(cwd, 'Fixture 0.0.1.dmg');
+	t.true(fs.existsSync(dmgPath));
 
-	t.true(fs.existsSync(path.join(cwd, 'Fixture 0.0.1.dmg')));
+	assertVolumeIconMatchesSnapshot(t, dmgPath);
 });
 
 test('binary plist', async t => {
@@ -34,7 +83,9 @@ test('binary plist', async t => {
 		}
 	}
 
-	t.true(fs.existsSync(path.join(cwd, 'Fixture 0.0.1.dmg')));
+	const dmgPath = path.join(cwd, 'Fixture 0.0.1.dmg');
+	t.true(fs.existsSync(dmgPath));
+	assertVolumeIconMatchesSnapshot(t, dmgPath);
 });
 
 test('app without icon', async t => {