Light test coverage for the stream-logger class

ui/tests/unit/utils/stream-logger-test.js

+import { module, test } from 'qunit';
+import { Promise } from 'rsvp';
+import sinon from 'sinon';
+import StreamLogger from 'nomad-ui/utils/classes/stream-logger';
+
+module('Unit | Util | StreamLogger', function() {
+  test('when a StreamLogger is stopped before the poll request responds, the request is immediately canceled upon completion', async function(assert) {
+    const fetchMock = new FetchMock();
+    const fetch = fetchMock.request();
+
+    const logger = StreamLogger.create({
+      logFetch: () => fetch,
+    });
+
+    logger.start();
+    logger.stop();
+
+    assert.notOk(logger.poll.isRunning);
+    assert.equal(fetchMock.reader.cancel.callCount, 0);
+
+    fetchMock.closeRequest();
+    await fetch;
+
+    assert.equal(fetchMock.reader.cancel.callCount, 1);
+  });
+
+  test('when the streaming request sends the done flag, the poll task completes', async function(assert) {
+    const fetchMock = new FetchMock();
+    const fetch = fetchMock.request();
+
+    const logger = StreamLogger.create({
+      logFetch: () => fetch,
+    });
+
+    logger.start();
+
+    assert.ok(logger.poll.isRunning);
+    assert.equal(fetchMock.reader.readSpy.callCount, 0);
+
+    fetchMock.closeRequest();
+    await fetch;
+
+    assert.notOk(logger.poll.isRunning);
+    assert.equal(fetchMock.reader.readSpy.callCount, 1);
+  });
+});
+
+class FetchMock {
+  constructor() {
+    this._closeRequest = null;
+    this.reader = new ReadableStreamMock();
+    this.response = new FetchResponseMock(this.reader);
+  }
+
+  request() {
+    if (this._closeRequest) {
+      throw new Error('Can only call FetchMock.request once');
+    }
+    return new Promise(resolve => {
+      this._closeRequest = resolve;
+    });
+  }
+
+  closeRequest() {
+    if (this._closeRequest) {
+      this._closeRequest(this.response);
+    } else {
+      throw new Error('Must call FetchMock.request() before FetchMock.closeRequest');
+    }
+  }
+}
+
+class FetchResponseMock {
+  constructor(reader) {
+    this.reader = reader;
+    this.body = {
+      getReader() {
+        return reader;
+      },
+    };
+  }
+}
+
+class ReadableStreamMock {
+  constructor() {
+    this.cancel = sinon.spy();
+    this.readSpy = sinon.spy();
+  }
+
+  read() {
+    this.readSpy();
+    return new Promise(resolve => {
+      resolve({ value: new ArrayBuffer(0), done: true });
+    });
+  }
+}