Add Couchbase support

Closes gh-3498

spring-boot-samples/spring-boot-sample-data-couchbase/src/test/java/sample/data/couchbase/SampleCouchbaseApplicationTests.java

@@ -0,0 +1,47 @@
+package sample.data.couchbase;
+
+import java.net.ConnectException;
+
+import org.junit.Rule;
+import org.junit.Test;
+
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.boot.test.OutputCapture;
+import org.springframework.core.NestedCheckedException;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class SampleCouchbaseApplicationTests {
+
+	@Rule
+	public OutputCapture outputCapture = new OutputCapture();
+
+	@Test
+	public void testDefaultSettings() throws Exception {
+		try {
+			new SpringApplicationBuilder(SampleCouchbaseApplication.class)
+					.run();
+		}
+		catch (RuntimeException ex) {
+			if (serverNotRunning(ex)) {
+				return;
+			}
+		}
+		String output = this.outputCapture.toString();
+		assertThat(output).contains("firstname='Alice', lastname='Smith'");
+	}
+
+	private boolean serverNotRunning(RuntimeException ex) {
+		@SuppressWarnings("serial")
+		NestedCheckedException nested = new NestedCheckedException("failed", ex) {
+		};
+		if (nested.contains(ConnectException.class)) {
+			Throwable root = nested.getRootCause();
+			if (root.getMessage().contains("Connection refused")) {
+				return true;
+			}
+		}
+		return false;
+	}
+
+}