diff --git a/apps/server/src/apps/helpers/admin-api-setup-helper.spec.ts b/apps/server/src/apps/helpers/admin-api-setup-helper.spec.ts
new file mode 100644
index 00000000000..e306a7cddd3
--- /dev/null
+++ b/apps/server/src/apps/helpers/admin-api-setup-helper.spec.ts
@@ -0,0 +1,160 @@
+import { createMock } from '@golevelup/ts-jest';
+import { Configuration } from '@hpi-schul-cloud/commons';
+import { IConfig } from '@hpi-schul-cloud/commons/lib/interfaces/IConfig';
+import {
+	PrometheusMetricsConfig,
+	createAPIResponseTimeMetricMiddleware,
+	createPrometheusMetricsApp,
+} from '@infra/metrics';
+import { Logger } from '@src/core/logger';
+import express, { Express, NextFunction, Request, RequestHandler, Response } from 'express';
+import {
+	PrometheusMetricsSetupState,
+	PrometheusMetricsSetupStateLoggable,
+	addPrometheusMetricsMiddlewaresIfEnabled,
+	createAndStartPrometheusMetricsAppIfEnabled,
+} from './prometheus-metrics';
+
+jest.mock('@infra/metrics', () => {
+	const moduleMock: unknown = {
+		...jest.requireActual('@infra/metrics'),
+		createAPIResponseTimeMetricMiddleware: jest.fn(),
+		createPrometheusMetricsApp: jest.fn(),
+	};
+
+	return moduleMock;
+});
+
+const testLogger = createMock<Logger>();
+
+let configBefore: IConfig;
+
+beforeAll(() => {
+	configBefore = Configuration.toObject({ plainSecrets: true });
+});
+
+beforeEach(() => {
+	Configuration.reset(configBefore);
+
+	const middlewareMock: RequestHandler = (_req: Request, _res: Response, next: NextFunction) => {
+		next();
+	};
+
+	(createAPIResponseTimeMetricMiddleware as jest.Mock).mockClear();
+	(createAPIResponseTimeMetricMiddleware as jest.Mock).mockReturnValue(middlewareMock);
+
+	const appMock = { listen: jest.fn() };
+
+	(createPrometheusMetricsApp as jest.Mock).mockClear();
+	(createPrometheusMetricsApp as jest.Mock).mockReturnValue(appMock);
+});
+
+afterAll(() => {
+	Configuration.reset(configBefore);
+});
+
+describe('PrometheusMetricsSetupStateLoggable', () => {
+	describe('getLogMessage', () => {
+		describe('should return a log message with proper content', () => {
+			const expectedMessage = 'Setting up Prometheus metrics...';
+
+			it.each([
+				[PrometheusMetricsSetupState.FEATURE_DISABLED_MIDDLEWARES_WILL_NOT_BE_CREATED],
+				[PrometheusMetricsSetupState.API_RESPONSE_TIME_METRIC_MIDDLEWARE_SUCCESSFULLY_ADDED],
+				[PrometheusMetricsSetupState.FEATURE_DISABLED_APP_WILL_NOT_BE_CREATED],
+				[PrometheusMetricsSetupState.COLLECTING_DEFAULT_METRICS_DISABLED],
+				[PrometheusMetricsSetupState.COLLECTING_METRICS_ROUTE_METRICS_DISABLED],
+			])("for the '%s' state", (state: PrometheusMetricsSetupState) => {
+				const testLogMessage = new PrometheusMetricsSetupStateLoggable(state).getLogMessage();
+
+				expect(testLogMessage).toHaveProperty('message', expectedMessage);
+				expect(testLogMessage).toHaveProperty('data', { state });
+			});
+		});
+	});
+});
+
+describe('addPrometheusMetricsMiddlewaresIfEnabled', () => {
+	let testApp: Express;
+	let testAppUseSpy: jest.SpyInstance;
+
+	beforeEach(() => {
+		testApp = express();
+		testAppUseSpy = jest.spyOn(testApp, 'use');
+	});
+
+	it('should create the API response time metric middleware and should add it to the given app', () => {
+		// To not create setters in the PrometheusMetricsConfig just for the unit tests
+		// purpose, we will enable the Prometheus metrics feature the way it should be
+		// enabled in a real app which is via the app configuration.
+		Configuration.set('FEATURE_PROMETHEUS_METRICS_ENABLED', true);
+		PrometheusMetricsConfig.reload();
+
+		addPrometheusMetricsMiddlewaresIfEnabled(testLogger, testApp);
+
+		expect(createAPIResponseTimeMetricMiddleware).toBeCalled();
+		expect(testAppUseSpy).toBeCalled();
+	});
+
+	it('should not create the API response time metric middleware and should not add it to the given app', () => {
+		Configuration.set('FEATURE_PROMETHEUS_METRICS_ENABLED', false);
+		PrometheusMetricsConfig.reload();
+
+		addPrometheusMetricsMiddlewaresIfEnabled(testLogger, testApp);
+
+		expect(createAPIResponseTimeMetricMiddleware).not.toBeCalled();
+		expect(testAppUseSpy).not.toBeCalled();
+	});
+});
+
+describe('createAndStartAdminApiServer', () => {
+	describe('should create Prometheus metrics app and run it', () => {
+		const testPort = 9000;
+		const testLoggerSpy = jest.spyOn(testLogger, 'info');
+
+		let appMockListenFn: jest.Mock;
+
+		beforeEach(() => {
+			testLoggerSpy.mockClear();
+			appMockListenFn = jest.fn();
+
+			(createPrometheusMetricsApp as jest.Mock).mockClear();
+			(createPrometheusMetricsApp as jest.Mock).mockReturnValue({ listen: appMockListenFn });
+		});
+
+		it.each([
+			[true, true],
+			[false, false],
+			[true, false],
+			[false, true],
+		])(
+			"with collecting default metrics set to '%s' and collecting metrics route metrics set to '%s'",
+			(collectDefaultMetrics: boolean, collectMetricsRouteMetrics: boolean) => {
+				Configuration.set('FEATURE_PROMETHEUS_METRICS_ENABLED', true);
+				Configuration.set('PROMETHEUS_METRICS_PORT', testPort);
+				Configuration.set('PROMETHEUS_METRICS_COLLECT_DEFAULT_METRICS', collectDefaultMetrics);
+				Configuration.set('PROMETHEUS_METRICS_COLLECT_METRICS_ROUTE_METRICS', collectMetricsRouteMetrics);
+				PrometheusMetricsConfig.reload();
+
+				createAndStartPrometheusMetricsAppIfEnabled(testLogger);
+
+				expect(createPrometheusMetricsApp).toBeCalledTimes(1);
+				expect(appMockListenFn).toHaveBeenLastCalledWith(testPort, expect.any(Function));
+
+				// Also test logging info message about running Prometheus metrics app.
+				// eslint-disable-next-line @typescript-eslint/no-unsafe-call,@typescript-eslint/no-unsafe-member-access
+				appMockListenFn.mock.lastCall[1]();
+				expect(testLoggerSpy).toBeCalledTimes(1);
+			}
+		);
+	});
+
+	it('should not create Prometheus metrics app if the whole feature is not enabled', () => {
+		Configuration.set('FEATURE_PROMETHEUS_METRICS_ENABLED', false);
+		PrometheusMetricsConfig.reload();
+
+		createAndStartPrometheusMetricsAppIfEnabled(testLogger);
+
+		expect(createPrometheusMetricsApp).not.toBeCalled();
+	});
+});
diff --git a/apps/server/src/modules/authentication/strategy/x-api-key.strategy.spec.ts b/apps/server/src/modules/authentication/strategy/x-api-key.strategy.spec.ts
index c6c526c8ed0..9bc03ab3a18 100644
--- a/apps/server/src/modules/authentication/strategy/x-api-key.strategy.spec.ts
+++ b/apps/server/src/modules/authentication/strategy/x-api-key.strategy.spec.ts
@@ -14,6 +14,7 @@ import { IXApiKeyConfig } from '../config/x-api-key.config';
 describe('XApiKeyStrategy', () => {
 	let module: TestingModule;
 	let strategy: XApiKeyStrategy;
+	let configService: ConfigService<IXApiKeyConfig, true>;
 	Configuration.set('ADMIN_API__ALLOWED_API_KEYS', '1ab2c3d4e5f61ab2c3d4e5f6');
 
 	beforeAll(async () => {
@@ -29,6 +30,7 @@ describe('XApiKeyStrategy', () => {
 		}).compile();
 
 		strategy = module.get(XApiKeyStrategy);
+		configService = module.get(ConfigService<IXApiKeyConfig, true>);
 	});
 
 	afterAll(async () => {
@@ -64,4 +66,12 @@ describe('XApiKeyStrategy', () => {
 			});
 		});
 	});
+
+	describe('constructor', () => {
+		it('should create strategy', () => {
+			const ApiKeyStrategy = new XApiKeyStrategy(configService);
+			expect(ApiKeyStrategy).toBeDefined();
+			expect(ApiKeyStrategy).toBeInstanceOf(XApiKeyStrategy);
+		});
+	});
 });