From d7ce91be575dc4f87bd48939081a2422a222d5c2 Mon Sep 17 00:00:00 2001
From: Sandeep Somavarapu <sasomava@microsoft.com>
Date: Mon, 9 Dec 2019 20:01:32 +0100
Subject: [PATCH] #86401 add merge tests

---
 .../userDataSync/common/extensionsMerge.ts    |  10 +-
 .../test/common/extensionsMerge.test.ts       | 412 +++++++++++++++++-
 2 files changed, 416 insertions(+), 6 deletions(-)

diff --git a/src/vs/platform/userDataSync/common/extensionsMerge.ts b/src/vs/platform/userDataSync/common/extensionsMerge.ts
index ce4a95ea624..364c7513ecd 100644
--- a/src/vs/platform/userDataSync/common/extensionsMerge.ts
+++ b/src/vs/platform/userDataSync/common/extensionsMerge.ts
@@ -59,8 +59,8 @@ export function merge(localExtensions: ISyncExtension[], remoteExtensions: ISync
 		return { added: [], removed: [], updated: [], remote: null };
 	}
 
-	const baseToLocal = lastSyncExtensionsMap ? compare(lastSyncExtensionsMap, localExtensionsMap, ignoredExtensionsSet) : { added: keys(localExtensionsMap).reduce((r, k) => { r.add(k); return r; }, new Set<string>()), removed: new Set<string>(), updated: new Set<string>() };
-	const baseToRemote = lastSyncExtensionsMap ? compare(lastSyncExtensionsMap, remoteExtensionsMap, ignoredExtensionsSet) : { added: keys(remoteExtensionsMap).reduce((r, k) => { r.add(k); return r; }, new Set<string>()), removed: new Set<string>(), updated: new Set<string>() };
+	const baseToLocal = compare(lastSyncExtensionsMap, localExtensionsMap, ignoredExtensionsSet);
+	const baseToRemote = compare(lastSyncExtensionsMap, remoteExtensionsMap, ignoredExtensionsSet);
 
 	const massageSyncExtension = (extension: ISyncExtension, key: string): ISyncExtension => {
 		const massagedExtension: ISyncExtension = {
@@ -144,8 +144,8 @@ export function merge(localExtensions: ISyncExtension[], remoteExtensions: ISync
 	return { added, removed, updated, remote };
 }
 
-function compare(from: Map<string, ISyncExtension>, to: Map<string, ISyncExtension>, ignoredExtensions: Set<string>): { added: Set<string>, removed: Set<string>, updated: Set<string> } {
-	const fromKeys = keys(from).filter(key => !ignoredExtensions.has(key));
+function compare(from: Map<string, ISyncExtension> | null, to: Map<string, ISyncExtension>, ignoredExtensions: Set<string>): { added: Set<string>, removed: Set<string>, updated: Set<string> } {
+	const fromKeys = from ? keys(from).filter(key => !ignoredExtensions.has(key)) : [];
 	const toKeys = keys(to).filter(key => !ignoredExtensions.has(key));
 	const added = toKeys.filter(key => fromKeys.indexOf(key) === -1).reduce((r, key) => { r.add(key); return r; }, new Set<string>());
 	const removed = fromKeys.filter(key => toKeys.indexOf(key) === -1).reduce((r, key) => { r.add(key); return r; }, new Set<string>());
@@ -155,7 +155,7 @@ function compare(from: Map<string, ISyncExtension>, to: Map<string, ISyncExtensi
 		if (removed.has(key)) {
 			continue;
 		}
-		const fromExtension = from.get(key)!;
+		const fromExtension = from!.get(key)!;
 		const toExtension = to.get(key);
 		if (!toExtension
 			|| fromExtension.enabled !== toExtension.enabled
diff --git a/src/vs/platform/userDataSync/test/common/extensionsMerge.test.ts b/src/vs/platform/userDataSync/test/common/extensionsMerge.test.ts
index a907e94b634..b98154aeb5e 100644
--- a/src/vs/platform/userDataSync/test/common/extensionsMerge.test.ts
+++ b/src/vs/platform/userDataSync/test/common/extensionsMerge.test.ts
@@ -62,6 +62,51 @@ suite('ExtensionsMerge - No Conflicts', () => {
 		assert.deepEqual(actual.remote, expected);
 	});
 
+	test('merge returns local extension if remote does not exist with skipped extensions', async () => {
+		const localExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+		const skippedExtension: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+		];
+		const expected: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+
+		const actual = merge(localExtensions, null, null, skippedExtension, []);
+
+		assert.deepEqual(actual.added, []);
+		assert.deepEqual(actual.removed, []);
+		assert.deepEqual(actual.updated, []);
+		assert.deepEqual(actual.remote, expected);
+	});
+
+	test('merge returns local extension if remote does not exist with skipped and ignored extensions', async () => {
+		const localExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+		const skippedExtension: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+		];
+		const expected: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+
+		const actual = merge(localExtensions, null, null, skippedExtension, ['a']);
+
+		assert.deepEqual(actual.added, []);
+		assert.deepEqual(actual.removed, []);
+		assert.deepEqual(actual.updated, []);
+		assert.deepEqual(actual.remote, expected);
+	});
+
 	test('merge local and remote extensions when there is no base', async () => {
 		const localExtensions: ISyncExtension[] = [
 			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
@@ -78,9 +123,374 @@ suite('ExtensionsMerge - No Conflicts', () => {
 			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
 		];
 
-		const actual = merge(localExtensions, remoteExtensions, null, [], ['A']);
+		const actual = merge(localExtensions, remoteExtensions, null, [], []);
+
+		assert.deepEqual(actual.added, [{ identifier: { id: 'b', uuid: 'b' }, enabled: true }, { identifier: { id: 'c', uuid: 'c' }, enabled: true }]);
+		assert.deepEqual(actual.removed, []);
+		assert.deepEqual(actual.updated, []);
+		assert.deepEqual(actual.remote, expected);
+	});
+
+	test('merge local and remote extensions when there is no base and with ignored extensions', async () => {
+		const localExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const remoteExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+		const expected: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+
+		const actual = merge(localExtensions, remoteExtensions, null, [], ['a']);
+
+		assert.deepEqual(actual.added, [{ identifier: { id: 'b', uuid: 'b' }, enabled: true }, { identifier: { id: 'c', uuid: 'c' }, enabled: true }]);
+		assert.deepEqual(actual.removed, []);
+		assert.deepEqual(actual.updated, []);
+		assert.deepEqual(actual.remote, expected);
+	});
+
+	test('merge local and remote extensions when remote is moved forwarded', async () => {
+		const baseExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const localExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const remoteExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+
+		const actual = merge(localExtensions, remoteExtensions, baseExtensions, [], []);
 
 		assert.deepEqual(actual.added, [{ identifier: { id: 'b', uuid: 'b' }, enabled: true }, { identifier: { id: 'c', uuid: 'c' }, enabled: true }]);
+		assert.deepEqual(actual.removed, [{ id: 'a', uuid: 'a' }, { id: 'd', uuid: 'd' }]);
+		assert.deepEqual(actual.updated, []);
+		assert.equal(actual.remote, null);
+	});
+
+	test('merge local and remote extensions when remote moved forwarded with ignored extensions', async () => {
+		const baseExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const localExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const remoteExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+
+		const actual = merge(localExtensions, remoteExtensions, baseExtensions, [], ['a']);
+
+		assert.deepEqual(actual.added, [{ identifier: { id: 'b', uuid: 'b' }, enabled: true }, { identifier: { id: 'c', uuid: 'c' }, enabled: true }]);
+		assert.deepEqual(actual.removed, [{ id: 'd', uuid: 'd' }]);
+		assert.deepEqual(actual.updated, []);
+		assert.equal(actual.remote, null);
+	});
+
+	test('merge local and remote extensions when remote is moved forwarded with skipped extensions', async () => {
+		const baseExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const localExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const skippedExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+		];
+		const remoteExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+
+		const actual = merge(localExtensions, remoteExtensions, baseExtensions, skippedExtensions, []);
+
+		assert.deepEqual(actual.added, [{ identifier: { id: 'b', uuid: 'b' }, enabled: true }, { identifier: { id: 'c', uuid: 'c' }, enabled: true }]);
+		assert.deepEqual(actual.removed, [{ id: 'd', uuid: 'd' }]);
+		assert.deepEqual(actual.updated, []);
+		assert.equal(actual.remote, null);
+	});
+
+	test('merge local and remote extensions when remote is moved forwarded with skipped and ignored extensions', async () => {
+		const baseExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const localExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const skippedExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+		];
+		const remoteExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+
+		const actual = merge(localExtensions, remoteExtensions, baseExtensions, skippedExtensions, ['b']);
+
+		assert.deepEqual(actual.added, [{ identifier: { id: 'c', uuid: 'c' }, enabled: true }]);
+		assert.deepEqual(actual.removed, [{ id: 'd', uuid: 'd' }]);
+		assert.deepEqual(actual.updated, []);
+		assert.equal(actual.remote, null);
+	});
+
+	test('merge local and remote extensions when local is moved forwarded', async () => {
+		const baseExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const localExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+		const remoteExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+
+		const actual = merge(localExtensions, remoteExtensions, baseExtensions, [], []);
+
+		assert.deepEqual(actual.added, []);
+		assert.deepEqual(actual.removed, []);
+		assert.deepEqual(actual.updated, []);
+		assert.deepEqual(actual.remote, localExtensions);
+	});
+
+	test('merge local and remote extensions when local is moved forwarded with ignored settings', async () => {
+		const baseExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const localExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+		const remoteExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+
+		const actual = merge(localExtensions, remoteExtensions, baseExtensions, [], ['b']);
+
+		assert.deepEqual(actual.added, []);
+		assert.deepEqual(actual.removed, []);
+		assert.deepEqual(actual.updated, []);
+		assert.deepEqual(actual.remote, [
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		]);
+	});
+
+	test('merge local and remote extensions when local is moved forwarded with skipped extensions', async () => {
+		const baseExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const skippedExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const localExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+		const remoteExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const expected: ISyncExtension[] = [
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+
+		const actual = merge(localExtensions, remoteExtensions, baseExtensions, skippedExtensions, []);
+
+		assert.deepEqual(actual.added, []);
+		assert.deepEqual(actual.removed, []);
+		assert.deepEqual(actual.updated, []);
+		assert.deepEqual(actual.remote, expected);
+	});
+
+	test('merge local and remote extensions when local is moved forwarded with skipped and ignored extensions', async () => {
+		const baseExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const skippedExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const localExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+		const remoteExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const expected: ISyncExtension[] = [
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+		];
+
+		const actual = merge(localExtensions, remoteExtensions, baseExtensions, skippedExtensions, ['c']);
+
+		assert.deepEqual(actual.added, []);
+		assert.deepEqual(actual.removed, []);
+		assert.deepEqual(actual.updated, []);
+		assert.deepEqual(actual.remote, expected);
+	});
+
+	test('merge local and remote extensions when both moved forwarded', async () => {
+		const baseExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const localExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+		const remoteExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'e', uuid: 'e' }, enabled: true },
+		];
+		const expected: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'e', uuid: 'e' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+
+		const actual = merge(localExtensions, remoteExtensions, baseExtensions, [], []);
+
+		assert.deepEqual(actual.added, [{ identifier: { id: 'e', uuid: 'e' }, enabled: true }]);
+		assert.deepEqual(actual.removed, [{ id: 'a', uuid: 'a' }]);
+		assert.deepEqual(actual.updated, []);
+		assert.deepEqual(actual.remote, expected);
+	});
+
+	test('merge local and remote extensions when both moved forwarded with ignored extensions', async () => {
+		const baseExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const localExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+		const remoteExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'e', uuid: 'e' }, enabled: true },
+		];
+		const expected: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'e', uuid: 'e' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+
+		const actual = merge(localExtensions, remoteExtensions, baseExtensions, [], ['a', 'e']);
+
+		assert.deepEqual(actual.added, []);
+		assert.deepEqual(actual.removed, []);
+		assert.deepEqual(actual.updated, []);
+		assert.deepEqual(actual.remote, expected);
+	});
+
+	test('merge local and remote extensions when both moved forwarded with skipped extensions', async () => {
+		const baseExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const skippedExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+		];
+		const localExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+		const remoteExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'e', uuid: 'e' }, enabled: true },
+		];
+		const expected: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'e', uuid: 'e' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+
+		const actual = merge(localExtensions, remoteExtensions, baseExtensions, skippedExtensions, []);
+
+		assert.deepEqual(actual.added, [{ identifier: { id: 'e', uuid: 'e' }, enabled: true }]);
+		assert.deepEqual(actual.removed, []);
+		assert.deepEqual(actual.updated, []);
+		assert.deepEqual(actual.remote, expected);
+	});
+
+	test('merge local and remote extensions when both moved forwarded with skipped and ignoredextensions', async () => {
+		const baseExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const skippedExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+		];
+		const localExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+		const remoteExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'e', uuid: 'e' }, enabled: true },
+		];
+		const expected: ISyncExtension[] = [
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'e', uuid: 'e' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+
+		const actual = merge(localExtensions, remoteExtensions, baseExtensions, skippedExtensions, ['e']);
+
+		assert.deepEqual(actual.added, []);
+		assert.deepEqual(actual.removed, []);
+		assert.deepEqual(actual.updated, []);
+		assert.deepEqual(actual.remote, expected);
+	});
+
+	test('merge when remote extension has no uuid and different extension id case', async () => {
+		const localExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'a', uuid: 'a' }, enabled: true },
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+		const remoteExtensions: ISyncExtension[] = [
+			{ identifier: { id: 'A' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+		];
+		const expected: ISyncExtension[] = [
+			{ identifier: { id: 'A' }, enabled: true },
+			{ identifier: { id: 'd', uuid: 'd' }, enabled: true },
+			{ identifier: { id: 'b', uuid: 'b' }, enabled: true },
+			{ identifier: { id: 'c', uuid: 'c' }, enabled: true },
+		];
+
+		const actual = merge(localExtensions, remoteExtensions, null, [], []);
+
+		assert.deepEqual(actual.added, [{ identifier: { id: 'd', uuid: 'd' }, enabled: true }]);
 		assert.deepEqual(actual.removed, []);
 		assert.deepEqual(actual.updated, []);
 		assert.deepEqual(actual.remote, expected);
-- 
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