[hotfix][cep] Added test harness output asserter

flink-libraries/flink-cep/src/test/java/org/apache/flink/cep/utils/OutputAsserter.java

@@ -0,0 +1,78 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.cep.utils;
+
+import org.apache.flink.streaming.api.watermark.Watermark;
+import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
+import org.apache.flink.streaming.util.OneInputStreamOperatorTestHarness;
+
+import java.util.Queue;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * Asserter for output from {@link OneInputStreamOperatorTestHarness}
+ */
+public class OutputAsserter {
+
+	private final Queue<?> output;
+
+	private OutputAsserter(Queue<?> output) {
+		this.output = output;
+	}
+
+	public static OutputAsserter assertOutput(Queue<?> output) {
+		return new OutputAsserter(output);
+	}
+
+	private AssertionError fail(Object record) {
+		return new AssertionError("Received unexpected element: " + record);
+	}
+
+	public <T> OutputAsserter nextElementEquals(T expected) {
+		final Object record = output.poll();
+		final Object actual;
+		if (record instanceof StreamRecord) {
+			// This is in case we assert side output
+			actual = ((StreamRecord) record).getValue();
+		} else {
+			// This is in case we assert the main output
+			actual = record;
+		}
+		assertThat(actual, is(expected));
+		return this;
+	}
+
+	public void hasNoMoreElements() {
+		assertTrue(output.isEmpty());
+	}
+
+	public OutputAsserter watermarkEquals(long timestamp) {
+		Object record = output.poll();
+		if (record instanceof Watermark) {
+			Watermark watermark = (Watermark) record;
+			assertThat(watermark.getTimestamp(), is(timestamp));
+		} else {
+			throw fail(record);
+		}
+		return this;
+	}
+}