feat: Handle OPTIONS requests in OperationHandler

src/http/ldp/OptionsOperationHandler.ts

@@ -0,0 +1,36 @@
+import type { ResourceSet } from '../../storage/ResourceSet';
+import { NotFoundHttpError } from '../../util/errors/NotFoundHttpError';
+import { NotImplementedHttpError } from '../../util/errors/NotImplementedHttpError';
+import { NoContentResponseDescription } from '../output/response/NoContentResponseDescription';
+import type { ResponseDescription } from '../output/response/ResponseDescription';
+import type { OperationHandlerInput } from './OperationHandler';
+import { OperationHandler } from './OperationHandler';
+
+/**
+ * Handles OPTIONS {@link Operation}s by always returning a 204.
+ */
+export class OptionsOperationHandler extends OperationHandler {
+  private readonly resourceSet: ResourceSet;
+
+  /**
+   * Uses a {@link ResourceSet} to determine the existence of the target resource which impacts the response code.
+   * @param resourceSet - {@link ResourceSet} that knows if the target resource exists or not.
+   */
+  public constructor(resourceSet: ResourceSet) {
+    super();
+    this.resourceSet = resourceSet;
+  }
+
+  public async canHandle({ operation }: OperationHandlerInput): Promise<void> {
+    if (operation.method !== 'OPTIONS') {
+      throw new NotImplementedHttpError('This handler only supports OPTIONS operations');
+    }
+  }
+
+  public async handle({ operation }: OperationHandlerInput): Promise<ResponseDescription> {
+    if (!await this.resourceSet.hasResource(operation.target)) {
+      throw new NotFoundHttpError();
+    }
+    return new NoContentResponseDescription();
+  }
+}

src/http/output/response/NoContentResponseDescription.ts

@@ -0,0 +1,10 @@
+import { ResponseDescription } from './ResponseDescription';
+
+/**
+ * Corresponds to a 204 response.
+ */
+export class NoContentResponseDescription extends ResponseDescription {
+  public constructor() {
+    super(204);
+  }
+}