Correctly returns running state of ConsulCatalogWatch.

Fixes gh-704

spring-cloud-consul-discovery/src/main/java/org/springframework/cloud/consul/discovery/ConsulCatalogWatch.java

@@ -111,7 +111,7 @@ public class ConsulCatalogWatch
 
 	@Override
 	public boolean isRunning() {
-		return false;
+		return this.running.get();
 	}
 
 	@Override

spring-cloud-consul-discovery/src/test/java/org/springframework/cloud/consul/discovery/ConsulCatalogWatchTests.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2013-2019 the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      https://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.springframework.cloud.consul.discovery;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.cloud.commons.util.InetUtils;
+import org.springframework.cloud.commons.util.InetUtilsProperties;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Spencer Gibb
+ */
+public class ConsulCatalogWatchTests {
+
+	@Test
+	public void isRunningReportsCorrectly() {
+		ConsulDiscoveryProperties properties = new ConsulDiscoveryProperties(
+				new InetUtils(new InetUtilsProperties()));
+		ConsulCatalogWatch watch = new ConsulCatalogWatch(properties, null) {
+			@Override
+			public void catalogServicesWatch() {
+				// do nothing
+			}
+		};
+		assertThat(watch.isRunning()).isFalse();
+		watch.start();
+		assertThat(watch.isRunning()).isTrue();
+		watch.stop();
+		assertThat(watch.isRunning()).isFalse();
+	}
+
+}