diff --git a/test/match/queue.test.ts b/test/match/queue.test.ts
new file mode 100644
index 0000000..de2cb39
--- /dev/null
+++ b/test/match/queue.test.ts
@@ -0,0 +1,54 @@
+import { describe, expect, it, mock } from 'bun:test';
+import { MATCH_STATES } from '../../src/lib/server/match/types';
+
+const mocks = {
+	db: {
+		query: {
+			matchParticipantPlayer: { findMany: mock() },
+			playerRating: { findFirst: mock() }
+		},
+		delete: mock()
+	}
+};
+
+mock.module('$lib/server/db', () => ({ db: mocks.db }));
+
+mock.module('drizzle-orm', () => ({
+	eq: mock(() => ({})),
+	asc: mock(() => ({})),
+	lt: mock(() => ({})),
+	inArray: mock(() => ({})),
+	sql: mock(() => ({}))
+}));
+
+mock.module('$lib/server/db/schema', () => ({
+	match: {},
+	matchQueue: {},
+	matchParticipantPlayer: {},
+	playerRating: {}
+}));
+
+mock.module('$lib/server/match/engine', () => ({
+	createMatch: mock()
+}));
+
+const { joinQueue } = await import('../../src/lib/server/match/queue');
+
+describe('joinQueue', () => {
+	it('throws when user is already in an active match', async () => {
+		mocks.db.delete.mockReturnValue({
+			where: mock(() => ({ returning: mock(() => Promise.resolve([])) }))
+		});
+
+		mocks.db.query.matchParticipantPlayer.findMany.mockResolvedValue([
+			{
+				participant: {
+					match: { id: 'match-1', state: MATCH_STATES.PLAYING, createdAt: new Date().toISOString() }
+				}
+			}
+		]);
+
+		await expect(joinQueue('user-1', 'team-1')).rejects.toThrow('You are already in an active match');
+		expect(mocks.db.query.playerRating.findFirst).not.toHaveBeenCalled();
+	});
+});