Add more unit tests

Include tests for emplace, modify fallback content negotiation logic.

TODO.md

@@ -26,3 +26,7 @@
 - [ ] Implement RPC endpoints
 - [ ] Implement `Vary` header (requires providing a `getHeader()` method in the request object to listen for obtained headers)
 - [ ] Add example on serving data as documents using `application/html` type.
+- [ ] OpenAPI support
+  - [ ] Swagger docs plugin
+    - [ ] Plugin support
+- [ ] Add option to reject content negotiation params with `406 Not Acceptable`

src/backend/servers/http/core.ts

@@ -384,40 +384,43 @@ export const createServer = (backendState: BackendState, serverParams = {} as Cr
 	const handleMiddlewareError = (processRequestErrRaw: Error) => (resourceReq: ResourceRequestContext, res: http.ServerResponse<RequestContext>) => {
 		const finalErr = processRequestErrRaw as ErrorPlainResponse;
 		const headers = finalErr.headers ?? {};
+		const language = resourceReq.cn.language ?? resourceReq.backend.cn.language;
+		const mediaType = resourceReq.cn.mediaType ?? resourceReq.backend.cn.mediaType;
+		const charset = resourceReq.cn.charset ?? resourceReq.backend.cn.charset;
 		let encoded: Buffer | undefined;
 		let serialized;
 		try {
-			serialized = typeof finalErr.body !== 'undefined' ? resourceReq.backend.cn.mediaType.serialize(finalErr.body) : undefined;
+			serialized = typeof finalErr.body !== 'undefined' ? mediaType.serialize(finalErr.body) : undefined;
 		} catch (cause) {
-			res.statusMessage = resourceReq.backend.cn.language.statusMessages['unableToSerializeResponse']?.replace(
+			res.statusMessage = language.statusMessages['unableToSerializeResponse']?.replace(
 				/\$RESOURCE/g,
-				resourceReq.resource!.state.itemName) ?? '';
+				resourceReq.resource.state.itemName) ?? '';
 			res.writeHead(constants.HTTP_STATUS_INTERNAL_SERVER_ERROR);
 			res.end();
 			return;
 		}
 
 		try {
-			encoded = typeof serialized !== 'undefined' ? resourceReq.backend.cn.charset.encode(serialized) : undefined;
+			encoded = typeof serialized !== 'undefined' ? charset.encode(serialized) : undefined;
 		} catch (cause) {
-			res.statusMessage = resourceReq.backend.cn.language.statusMessages['unableToEncodeResponse']?.replace(/\$RESOURCE/g,
-				resourceReq.resource!.state.itemName) ?? '';
+			res.statusMessage = language.statusMessages['unableToEncodeResponse']?.replace(/\$RESOURCE/g,
+				resourceReq.resource.state.itemName) ?? '';
 			res.writeHead(constants.HTTP_STATUS_INTERNAL_SERVER_ERROR);
 			res.end();
 			return;
 		}
 
 		headers['Content-Type'] = [
-			resourceReq.backend.cn.mediaType.name,
-			typeof serialized !== 'undefined' ? `charset=${resourceReq.backend.cn.charset.name}` : '',
+			mediaType.name,
+			typeof serialized !== 'undefined' ? `charset=${charset.name}` : '',
 		]
 			.filter((s) => s.length > 0)
 			.join('; ');
 
-		res.statusMessage = resourceReq.backend.cn.language.statusMessages[
+		res.statusMessage = language.statusMessages[
 			finalErr.statusMessage ?? 'internalServerError'
 		]?.replace(/\$RESOURCE/g,
-			resourceReq.resource!.state.itemName);
+			resourceReq.resource.state.itemName);
 		res.writeHead(finalErr.statusCode ?? constants.HTTP_STATUS_INTERNAL_SERVER_ERROR, headers);
 		if (typeof encoded !== 'undefined') {
 			res.end(encoded);
@@ -430,6 +433,10 @@ export const createServer = (backendState: BackendState, serverParams = {} as Cr
 		const plainReq = await decorateRequest(reqRaw); // TODO add type safety here, put handleGetRoot as its own middleware as it does not concern over any resource
 		if (typeof plainReq.resource !== 'undefined') {
 			const resourceReq = plainReq as ResourceRequestContext;
+			const language = resourceReq.cn.language ?? resourceReq.backend.cn.language;
+			const mediaType = resourceReq.cn.mediaType ?? resourceReq.backend.cn.mediaType;
+			const charset = resourceReq.cn.charset ?? resourceReq.backend.cn.charset;
+
 			// TODO custom middlewares
 			const effectiveMiddlewares = (
 				typeof resourceReq.resourceId === 'string'
@@ -452,7 +459,7 @@ export const createServer = (backendState: BackendState, serverParams = {} as Cr
 				...(
 					middlewareState.headers ?? {}
 				),
-				'Content-Language': resourceReq.cn.language.name,
+				'Content-Language': language.name,
 			};
 			if (middlewareState instanceof http.ServerResponse) {
 				// TODO streaming responses
@@ -464,10 +471,10 @@ export const createServer = (backendState: BackendState, serverParams = {} as Cr
 				if (typeof middlewareState.body !== 'undefined') {
 					let serialized;
 					try {
-						serialized = resourceReq.cn.mediaType.serialize(middlewareState.body);
+						serialized = mediaType.serialize(middlewareState.body);
 					} catch (cause) {
 						const headers: Record<string, string> = {
-							'Content-Language': resourceReq.backend.cn.language.name,
+							'Content-Language': language.name,
 						};
 						if (resourceReq.method === 'POST') {
 							headers['Accept-Post'] = Array.from(resourceReq.backend.app.mediaTypes.keys()).join(',');
@@ -482,7 +489,7 @@ export const createServer = (backendState: BackendState, serverParams = {} as Cr
 								return `${mimeType}/merge-patch+${mimeSubtype}`;
 							}).join(',');
 						}
-						res.statusMessage = resourceReq.backend.cn.language.statusMessages['unableToSerializeResponse']?.replace(
+						res.statusMessage = language.statusMessages['unableToSerializeResponse']?.replace(
 							/\$RESOURCE/g,
 							resourceReq.resource!.state.itemName) ?? '';
 						res.writeHead(constants.HTTP_STATUS_INTERNAL_SERVER_ERROR, headers);
@@ -491,24 +498,24 @@ export const createServer = (backendState: BackendState, serverParams = {} as Cr
 					}
 
 					try {
-						encoded = resourceReq.cn.charset.encode(serialized);
+						encoded = charset.encode(serialized);
 					} catch (cause) {
-						res.statusMessage = resourceReq.backend.cn.language.statusMessages['unableToEncodeResponse']?.replace(/\$RESOURCE/g,
+						res.statusMessage = language.statusMessages['unableToEncodeResponse']?.replace(/\$RESOURCE/g,
 							resourceReq.resource!.state.itemName) ?? '';
 						res.writeHead(constants.HTTP_STATUS_INTERNAL_SERVER_ERROR, {
-							'Content-Language': resourceReq.backend.cn.language.name,
+							'Content-Language': language.name,
 						});
 						res.end();
 						return;
 					}
 
 					headers['Content-Type'] = [
-						resourceReq.cn.mediaType.name,
-						`charset=${resourceReq.cn.charset.name}`,
+						mediaType.name,
+						`charset=${charset.name}`,
 					].join('; ');
 				}
 
-				const statusMessageKey = middlewareState.statusMessage ? resourceReq.cn.language.statusMessages[middlewareState.statusMessage] : undefined;
+				const statusMessageKey = middlewareState.statusMessage ? language.statusMessages[middlewareState.statusMessage] : undefined;
 				res.statusMessage = statusMessageKey?.replace(/\$RESOURCE/g, resourceReq.resource!.state.itemName) ?? '';
 				res.writeHead(middlewareState.statusCode, headers);
 				if (typeof encoded !== 'undefined') {

src/backend/servers/http/decorators/backend/content-negotiation.ts

@@ -4,7 +4,7 @@ import Negotiator from 'negotiator';
 
 declare module '../../../../common' {
 	interface RequestContext {
-		cn: ContentNegotiation;
+		cn: Partial<ContentNegotiation>;
 	}
 }
 
@@ -20,9 +20,9 @@ export const decorateRequestWithContentNegotiation: RequestDecorator = (req) =>
 	const mediaTypeCandidate = negotiator.mediaType(availableMediaTypes.map((l) => l.name)) ?? req.backend.cn.mediaType.name;
 
 	req.cn = {
-		language: req.backend.app.languages.get(languageCandidate) ?? req.backend.cn.language,
-		mediaType: req.backend.app.mediaTypes.get(mediaTypeCandidate) ?? req.backend.cn.mediaType,
-		charset: req.backend.app.charsets.get(charsetCandidate) ?? req.backend.cn.charset,
+		language: req.backend.app.languages.get(languageCandidate),
+		mediaType: req.backend.app.mediaTypes.get(mediaTypeCandidate),
+		charset: req.backend.app.charsets.get(charsetCandidate),
 	};
 
 	return req;

test/e2e/http/default.test.ts → test/handlers/http/default.test.ts

@@ -10,9 +10,15 @@ import {
 } from 'vitest';
 import {constants} from 'http2';
 import {Backend} from '../../../src/backend';
-import {application, resource, validation as v, Resource, Application} from '../../../src/common';
+import {
+	application,
+	resource,
+	validation as v,
+	Resource,
+	Application,
+} from '../../../src/common';
 import { autoIncrement } from '../../fixtures';
-import {createTestClient, DummyDataSource, TestClient} from '../../utils';
+import {createTestClient, DummyDataSource, TEST_LANGUAGE, TestClient} from '../../utils';
 import {DataSource} from '../../../src/backend/data-source';
 
 const PORT = 3000;
@@ -24,7 +30,7 @@ const ACCEPT_CHARSET = 'utf-8';
 const CONTENT_TYPE_CHARSET = 'utf-8';
 const CONTENT_TYPE = ACCEPT;
 
-describe.only('happy path', () => {
+describe('happy path', () => {
 	let Piano: Resource;
 	let app: Application;
 	let dataSource: DataSource;
@@ -51,6 +57,7 @@ describe.only('happy path', () => {
 		app = application({
 			name: 'piano-service',
 		})
+			.language(TEST_LANGUAGE)
 			.resource(Piano);
 
 		dataSource = new DummyDataSource();
@@ -120,7 +127,7 @@ describe.only('happy path', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_OK);
-			expect(res).toHaveProperty('statusMessage', 'Piano Collection Fetched');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.resourceCollectionFetched);
 			expect(res.headers).toHaveProperty('content-type', expect.stringContaining(ACCEPT));
 
 			if (typeof resData === 'undefined') {
@@ -138,7 +145,7 @@ describe.only('happy path', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_OK);
-			expect(res).toHaveProperty('statusMessage', 'Piano Collection Fetched');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.resourceCollectionFetched);
 		});
 
 		it('returns options', async () => {
@@ -148,7 +155,7 @@ describe.only('happy path', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_NO_CONTENT);
-			expect(res).toHaveProperty('statusMessage', 'Provide Options');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.provideOptions);
 			const allowedMethods = res.headers.allow?.split(',').map((s) => s.trim()) ?? [];
 			expect(allowedMethods).toContain('GET');
 			expect(allowedMethods).toContain('HEAD');
@@ -182,7 +189,7 @@ describe.only('happy path', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_OK);
-			expect(res).toHaveProperty('statusMessage', 'Piano Fetched');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.resourceFetched);
 			expect(res.headers).toHaveProperty('content-type', expect.stringContaining(ACCEPT));
 			if (typeof resData === 'undefined') {
 				expect.fail('Response body must be defined.');
@@ -199,7 +206,7 @@ describe.only('happy path', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_OK);
-			expect(res).toHaveProperty('statusMessage', 'Piano Fetched');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.resourceFetched);
 		});
 
 		it('returns options', async () => {
@@ -209,7 +216,7 @@ describe.only('happy path', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_NO_CONTENT);
-			expect(res).toHaveProperty('statusMessage', 'Provide Options');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.provideOptions);
 			const allowedMethods = res.headers.allow?.split(',').map((s) => s.trim()) ?? [];
 			expect(allowedMethods).toContain('GET');
 			expect(allowedMethods).toContain('HEAD');
@@ -254,7 +261,7 @@ describe.only('happy path', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_CREATED);
-			expect(res).toHaveProperty('statusMessage', 'Piano Created');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.resourceCreated);
 			expect(res.headers).toHaveProperty('content-type', expect.stringContaining(ACCEPT));
 			expect(res.headers).toHaveProperty('location', `${BASE_PATH}/pianos/2`);
 
@@ -276,13 +283,13 @@ describe.only('happy path', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_NO_CONTENT);
-			expect(res).toHaveProperty('statusMessage', 'Provide Options');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.provideOptions);
 			const allowedMethods = res.headers.allow?.split(',').map((s) => s.trim()) ?? [];
 			expect(allowedMethods).toContain('POST');
 		});
 	});
 
-	describe.only('patching items', () => {
+	describe('patching items', () => {
 		const existingResource = {
 			id: 1,
 			brand: 'Yamaha'
@@ -322,7 +329,7 @@ describe.only('happy path', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_NO_CONTENT);
-			expect(res).toHaveProperty('statusMessage', 'Provide Options');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.provideOptions);
 			const allowedMethods = res.headers.allow?.split(',').map((s) => s.trim()) ?? [];
 			expect(allowedMethods).toContain('PATCH');
 			const acceptPatch = res.headers['accept-patch']?.split(',').map((s) => s.trim()) ?? [];
@@ -346,7 +353,7 @@ describe.only('happy path', () => {
 				});
 
 				expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_OK);
-				expect(res).toHaveProperty('statusMessage', 'Piano Patched');
+				expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.resourcePatched);
 				expect(res.headers).toHaveProperty('content-type', expect.stringContaining(ACCEPT));
 
 				if (typeof resData === 'undefined') {
@@ -366,7 +373,7 @@ describe.only('happy path', () => {
 				Piano.canPatch(false).canPatch(['delta']);
 			});
 
-			it.only('returns data', async () => {
+			it('returns data', async () => {
 				const [res, resData] = await client({
 					method: 'PATCH',
 					path: `${BASE_PATH}/pianos/${existingResource.id}`,
@@ -383,7 +390,7 @@ describe.only('happy path', () => {
 				});
 
 				expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_OK);
-				expect(res).toHaveProperty('statusMessage', 'Piano Patched');
+				expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.resourcePatched);
 				expect(res.headers).toHaveProperty('content-type', expect.stringContaining(ACCEPT));
 
 				if (typeof resData === 'undefined') {
@@ -433,7 +440,7 @@ describe.only('happy path', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_OK);
-			expect(res).toHaveProperty('statusMessage', 'Piano Replaced');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.resourceReplaced);
 			expect(res.headers).toHaveProperty('content-type', expect.stringContaining(ACCEPT));
 
 			if (typeof resData === 'undefined') {
@@ -465,7 +472,7 @@ describe.only('happy path', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_CREATED);
-			expect(res).toHaveProperty('statusMessage', 'Piano Created');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.resourceCreated);
 			expect(res.headers).toHaveProperty('content-type', expect.stringContaining(ACCEPT));
 			expect(res.headers).toHaveProperty('location', `${BASE_PATH}/pianos/${newId}`);
 
@@ -487,7 +494,7 @@ describe.only('happy path', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_NO_CONTENT);
-			expect(res).toHaveProperty('statusMessage', 'Provide Options');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.provideOptions);
 			const allowedMethods = res.headers.allow?.split(',').map((s) => s.trim()) ?? [];
 			expect(allowedMethods).toContain('PUT');
 		});
@@ -526,7 +533,7 @@ describe.only('happy path', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_NO_CONTENT);
-			expect(res).toHaveProperty('statusMessage', 'Piano Deleted');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.resourceDeleted);
 			expect(res.headers).not.toHaveProperty('content-type');
 			expect(resData).toBeUndefined();
 		});
@@ -538,7 +545,7 @@ describe.only('happy path', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_NO_CONTENT);
-			expect(res).toHaveProperty('statusMessage', 'Provide Options');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.provideOptions);
 			const allowedMethods = res.headers.allow?.split(',').map((s) => s.trim()) ?? [];
 			expect(allowedMethods).toContain('DELETE');
 		});

test/e2e/http/error-handling.test.ts → test/handlers/http/error-handling.test.ts

@@ -11,10 +11,10 @@ import {constants} from 'http2';
 import {Backend} from '../../../src/backend';
 import {application, resource, validation as v, Resource, Application, Delta} from '../../../src/common';
 import { autoIncrement } from '../../fixtures';
-import {createTestClient, TestClient, DummyDataSource, DummyError} from '../../utils';
+import {createTestClient, TestClient, DummyDataSource, DummyError, TEST_LANGUAGE} from '../../utils';
 import {DataSource} from '../../../src/backend/data-source';
 
-const PORT = 4001;
+const PORT = 3001;
 const HOST = '127.0.0.1';
 const BASE_PATH = '/api';
 const ACCEPT = 'application/json';
@@ -50,6 +50,7 @@ describe('error handling', () => {
 		app = application({
 			name: 'piano-service',
 		})
+			.language(TEST_LANGUAGE)
 			.resource(Piano);
 
 		dataSource = new DummyDataSource();
@@ -117,7 +118,7 @@ describe('error handling', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_INTERNAL_SERVER_ERROR);
-			expect(res).toHaveProperty('statusMessage', 'Unable To Fetch Piano Collection');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.unableToFetchResourceCollection);
 		});
 
 		it('throws on HEAD method', async () => {
@@ -131,7 +132,7 @@ describe('error handling', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_INTERNAL_SERVER_ERROR);
-			expect(res).toHaveProperty('statusMessage', 'Unable To Fetch Piano Collection');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.unableToFetchResourceCollection);
 		});
 	});
 
@@ -155,7 +156,7 @@ describe('error handling', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_INTERNAL_SERVER_ERROR);
-			expect(res).toHaveProperty('statusMessage', 'Unable To Fetch Piano');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.unableToFetchResource);
 		});
 
 		it('throws on HEAD method', async () => {
@@ -169,7 +170,7 @@ describe('error handling', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_INTERNAL_SERVER_ERROR);
-			expect(res).toHaveProperty('statusMessage', 'Unable To Fetch Piano');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.unableToFetchResource);
 		});
 
 		it('throws on item not found', async () => {
@@ -228,7 +229,7 @@ describe('error handling', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_INTERNAL_SERVER_ERROR);
-			expect(res).toHaveProperty('statusMessage', 'Unable To Assign ID From Piano Data Source');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.unableToAssignIdFromResourceDataSource);
 		});
 
 		it('throws on error creating resource', async () => {
@@ -247,7 +248,7 @@ describe('error handling', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_INTERNAL_SERVER_ERROR);
-			expect(res).toHaveProperty('statusMessage', 'Unable To Create Piano');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.unableToCreateResource);
 		});
 	});
 
@@ -279,7 +280,7 @@ describe('error handling', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_INTERNAL_SERVER_ERROR);
-			expect(res).toHaveProperty('statusMessage', 'Unable To Fetch Piano');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.unableToFetchResource);
 			Piano.canPatch(false);
 		});
 
@@ -299,7 +300,7 @@ describe('error handling', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_NOT_FOUND);
-			expect(res).toHaveProperty('statusMessage', 'Patch Non-Existing Piano');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.patchNonExistingResource);
 			Piano.canPatch(false);
 		});
 
@@ -327,7 +328,7 @@ describe('error handling', () => {
 				});
 
 				expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_UNSUPPORTED_MEDIA_TYPE);
-				expect(res).toHaveProperty('statusMessage', 'Invalid Piano Patch Type');
+				expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.invalidResourcePatchType);
 			});
 		});
 
@@ -351,7 +352,7 @@ describe('error handling', () => {
 				});
 
 				expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_UNSUPPORTED_MEDIA_TYPE);
-				expect(res).toHaveProperty('statusMessage', 'Invalid Piano Patch Type');
+				expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.invalidResourcePatchType);
 			});
 
 			it('throws on operating with a delta to an attribute outside the schema', async () => {
@@ -371,7 +372,7 @@ describe('error handling', () => {
 				});
 
 				expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_UNPROCESSABLE_ENTITY);
-				expect(res).toHaveProperty('statusMessage', 'Invalid Piano Patch');
+				expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.invalidResourcePatch);
 			});
 
 			it('throws on operating a delta with mismatched value type', async () => {
@@ -391,10 +392,10 @@ describe('error handling', () => {
 				});
 
 				expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_UNPROCESSABLE_ENTITY);
-				expect(res).toHaveProperty('statusMessage', 'Invalid Piano Patch');
+				expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.invalidResourcePatch);
 			});
 
-			it.skip('throws on performing an invalid delta', async () => {
+			it('throws on performing an invalid delta', async () => {
 				const [res] = await client({
 					method: 'PATCH',
 					path: `${BASE_PATH}/pianos/${existingResource.id}`,
@@ -411,12 +412,12 @@ describe('error handling', () => {
 				});
 
 				expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_UNPROCESSABLE_ENTITY);
-				expect(res).toHaveProperty('statusMessage', 'Invalid Piano Patch');
+				expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.invalidResourcePatch);
 			});
 		});
 	});
 
-	describe.skip('emplacing items', () => {
+	describe('emplacing items', () => {
 		const existingResource = {
 			id: 1,
 			brand: 'Yamaha'
@@ -440,6 +441,21 @@ describe('error handling', () => {
 		afterEach(() => {
 			Piano.canEmplace(false);
 		});
+
+		it('throws on unable to emplace', async () => {
+			vi
+				.spyOn(DummyDataSource.prototype, 'emplace')
+				.mockImplementationOnce(() => { throw new DummyError() });
+
+			const [res] = await client({
+				method: 'PUT',
+				path: `${BASE_PATH}/pianos/${existingResource.id}`,
+				body: newData,
+			});
+
+			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_INTERNAL_SERVER_ERROR);
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.unableToEmplaceResource);
+		});
 	});
 
 	describe('deleting items', () => {
@@ -469,7 +485,7 @@ describe('error handling', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_INTERNAL_SERVER_ERROR);
-			expect(res).toHaveProperty('statusMessage', 'Unable To Fetch Piano');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.unableToFetchResource);
 		});
 
 		it('throws on item not found', async () => {
@@ -483,7 +499,7 @@ describe('error handling', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_NOT_FOUND);
-			expect(res).toHaveProperty('statusMessage', 'Delete Non-Existing Piano');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.deleteNonExistingResource);
 		});
 
 		it('throws on unable to delete item', async () => {
@@ -501,7 +517,7 @@ describe('error handling', () => {
 			});
 
 			expect(res).toHaveProperty('statusCode', constants.HTTP_STATUS_INTERNAL_SERVER_ERROR);
-			expect(res).toHaveProperty('statusMessage', 'Unable To Delete Piano');
+			expect(res).toHaveProperty('statusMessage', TEST_LANGUAGE.statusMessages.unableToDeleteResource);
 		});
 	});
 });

test/utils.ts

@@ -1,6 +1,7 @@
 import {IncomingHttpHeaders, IncomingMessage, OutgoingHttpHeaders, request, RequestOptions} from 'http';
 import {Method} from '../src/backend/common';
 import {DataSource} from '../src/backend/data-source';
+import {FALLBACK_LANGUAGE, Language} from '../src/common';
 
 interface ClientParams {
 	method: Method;
@@ -188,3 +189,52 @@ export class DummyDataSource implements DataSource {
 		this.resource.dataSource = this;
 	}
 }
+
+export const TEST_LANGUAGE: Language = {
+	name: FALLBACK_LANGUAGE.name,
+	statusMessages: {
+		unableToInitializeResourceDataSource: 'unableToInitializeResourceDataSource',
+		unableToFetchResourceCollection: 'unableToFetchResourceCollection',
+		unableToFetchResource: 'unableToFetchResource',
+		resourceIdNotGiven: 'resourceIdNotGiven',
+		languageNotAcceptable: 'languageNotAcceptable',
+		encodingNotAcceptable: 'encodingNotAcceptable',
+		mediaTypeNotAcceptable: 'mediaTypeNotAcceptable',
+		methodNotAllowed: 'methodNotAllowed',
+		urlNotFound: 'urlNotFound',
+		badRequest: 'badRequest',
+		ok: 'ok',
+		resourceCollectionFetched: 'resourceCollectionFetched',
+		resourceFetched: 'resourceFetched',
+		resourceNotFound: 'resourceNotFound',
+		deleteNonExistingResource: 'deleteNonExistingResource',
+		unableToCreateResource: 'unableToCreateResource',
+		unableToBindResourceDataSource: 'unableToBindResourceDataSource',
+		unableToGenerateIdFromResourceDataSource: 'unableToGenerateIdFromResourceDataSource',
+		unableToAssignIdFromResourceDataSource: 'unableToAssignIdFromResourceDataSource',
+		unableToEmplaceResource: 'unableToEmplaceResource',
+		unableToSerializeResponse: 'unableToSerializeResponse',
+		unableToEncodeResponse: 'unableToEncodeResponse',
+		unableToDeleteResource: 'unableToDeleteResource',
+		unableToDeserializeResource: 'unableToDeserializeResource',
+		unableToDecodeResource: 'unableToDecodeResource',
+		resourceDeleted: 'resourceDeleted',
+		unableToDeserializeRequest: 'unableToDeserializeRequest',
+		patchNonExistingResource: 'patchNonExistingResource',
+		unableToPatchResource: 'unableToPatchResource',
+		invalidResourcePatch: 'invalidResourcePatch',
+		invalidResourcePatchType: 'invalidResourcePatchType',
+		invalidResource: 'invalidResource',
+		resourcePatched: 'resourcePatched',
+		resourceCreated: 'resourceCreated',
+		resourceReplaced: 'resourceReplaced',
+		notImplemented: 'notImplemented',
+		provideOptions: 'provideOptions',
+		internalServerError: 'internalServerError',
+	},
+	bodies: {
+		languageNotAcceptable: [],
+		encodingNotAcceptable: [],
+		mediaTypeNotAcceptable: [],
+	},
+};