From 482991cb9a94bd2b77b7ad64e0fc11edf5db1c50 Mon Sep 17 00:00:00 2001
From: Joachim Van Herwegen <joachimvh@gmail.com>
Date: Wed, 22 Jul 2020 13:43:26 +0200
Subject: [PATCH] feat: Add OperationHandler for PATCH

---
 .../operations/SimplePatchOperationHandler.ts | 26 +++++++++++++++++++
 .../SimplePatchOperationHandler.test.ts       | 24 +++++++++++++++++
 2 files changed, 50 insertions(+)
 create mode 100644 src/ldp/operations/SimplePatchOperationHandler.ts
 create mode 100644 test/unit/ldp/operations/SimplePatchOperationHandler.test.ts

diff --git a/src/ldp/operations/SimplePatchOperationHandler.ts b/src/ldp/operations/SimplePatchOperationHandler.ts
new file mode 100644
index 000000000..532ed5281
--- /dev/null
+++ b/src/ldp/operations/SimplePatchOperationHandler.ts
@@ -0,0 +1,26 @@
+import { Operation } from './Operation';
+import { OperationHandler } from './OperationHandler';
+import { Patch } from '../http/Patch';
+import { ResourceStore } from '../../storage/ResourceStore';
+import { ResponseDescription } from './ResponseDescription';
+import { UnsupportedHttpError } from '../../util/errors/UnsupportedHttpError';
+
+export class SimplePatchOperationHandler extends OperationHandler {
+  private readonly store: ResourceStore;
+
+  public constructor(store: ResourceStore) {
+    super();
+    this.store = store;
+  }
+
+  public async canHandle(input: Operation): Promise<void> {
+    if (input.method !== 'PATCH') {
+      throw new UnsupportedHttpError('This handler only supports PATCH operations.');
+    }
+  }
+
+  public async handle(input: Operation): Promise<ResponseDescription> {
+    await this.store.modifyResource(input.target, input.body as Patch);
+    return { identifier: input.target };
+  }
+}
diff --git a/test/unit/ldp/operations/SimplePatchOperationHandler.test.ts b/test/unit/ldp/operations/SimplePatchOperationHandler.test.ts
new file mode 100644
index 000000000..1b51b1c96
--- /dev/null
+++ b/test/unit/ldp/operations/SimplePatchOperationHandler.test.ts
@@ -0,0 +1,24 @@
+import { Operation } from '../../../../src/ldp/operations/Operation';
+import { ResourceStore } from '../../../../src/storage/ResourceStore';
+import { SimplePatchOperationHandler } from '../../../../src/ldp/operations/SimplePatchOperationHandler';
+import { UnsupportedHttpError } from '../../../../src/util/errors/UnsupportedHttpError';
+
+describe('A SimplePatchOperationHandler', (): void => {
+  const store = {} as unknown as ResourceStore;
+  const handler = new SimplePatchOperationHandler(store);
+  beforeEach(async(): Promise<void> => {
+    store.modifyResource = jest.fn(async(): Promise<void> => undefined);
+  });
+
+  it('only supports GET operations.', async(): Promise<void> => {
+    await expect(handler.canHandle({ method: 'PATCH' } as Operation)).resolves.toBeUndefined();
+    await expect(handler.canHandle({ method: 'GET' } as Operation)).rejects.toThrow(UnsupportedHttpError);
+  });
+
+  it('deletes the resource from the store and returns its identifier.', async(): Promise<void> => {
+    await expect(handler.handle({ target: { path: 'url' }, body: { dataType: 'patch' }} as Operation))
+      .resolves.toEqual({ identifier: { path: 'url' }});
+    expect(store.modifyResource).toHaveBeenCalledTimes(1);
+    expect(store.modifyResource).toHaveBeenLastCalledWith({ path: 'url' }, { dataType: 'patch' });
+  });
+});