Make Health and Status immutable

Update Health and Status objects to be immutable, update the existing
builder methods to return new instances and add static convenience
methods to Health.

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/AbstractHealthAggregator.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.actuate.health;
 
 import java.util.ArrayList;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 
@@ -31,21 +32,21 @@ public abstract class AbstractHealthAggregator implements HealthAggregator {
 
 	@Override
 	public final Health aggregate(Map<String, Health> healths) {
-		Health health = new Health();
-		List<Status> status = new ArrayList<Status>();
+		List<Status> statusCandidates = new ArrayList<Status>();
+		Map<String, Object> details = new LinkedHashMap<String, Object>();
 		for (Map.Entry<String, Health> entry : healths.entrySet()) {
-			health.withDetail(entry.getKey(), entry.getValue());
-			status.add(entry.getValue().getStatus());
+			details.put(entry.getKey(), entry.getValue());
+			statusCandidates.add(entry.getValue().getStatus());
 		}
-		health.status(aggregateStatus(status));
-		return health;
+		return new Health(aggregateStatus(statusCandidates), details);
 	}
 
 	/**
-	 * Actual aggregation logic.
-	 * @param status list of given {@link Status} instances to aggregate
-	 * @return aggregated {@link Status}
+	 * Return the single 'aggregate' status that should be used from the specified
+	 * candidates.
+	 * @param candidates
+	 * @return a single status
 	 */
-	protected abstract Status aggregateStatus(List<Status> status);
+	protected abstract Status aggregateStatus(List<Status> candidates);
 
 }

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/AbstractHealthIndicator.java

@@ -21,7 +21,7 @@ package org.springframework.boot.actuate.health;
  * {@link Health} instance and error handling.
  * <p>
  * This implementation is only suitable if an {@link Exception} raised from
- * {@link #doHealthCheck(Health)} should create a {@link Status#DOWN} health status.
+ * {@link #doHealthCheck()} should create a {@link Status#DOWN} health status.
  * 
  * @author Christian Dupuis
  * @since 1.1.0
@@ -30,21 +30,19 @@ public abstract class AbstractHealthIndicator implements HealthIndicator {
 
 	@Override
 	public final Health health() {
-		Health health = new Health();
 		try {
-			doHealthCheck(health);
+			return doHealthCheck();
 		}
 		catch (Exception ex) {
-			health.down().withException(ex);
+			return Health.down(ex);
 		}
-		return health;
 	}
 
 	/**
 	 * Actual health check logic.
-	 * @param health {@link Health} instance of report status.
+	 * @return the {@link Health}
 	 * @throws Exception any {@link Exception} that should create a {@link Status#DOWN}
 	 * system status.
 	 */
-	protected abstract void doHealthCheck(Health health) throws Exception;
+	protected abstract Health doHealthCheck() throws Exception;
 }

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/Health.java

@@ -16,11 +16,11 @@
 
 package org.springframework.boot.actuate.health;
 
+import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.Map;
 
 import org.springframework.util.Assert;
-import org.springframework.util.ObjectUtils;
 
 import com.fasterxml.jackson.annotation.JsonAnyGetter;
 import com.fasterxml.jackson.annotation.JsonAnySetter;
@@ -29,8 +29,7 @@ import com.fasterxml.jackson.annotation.JsonInclude.Include;
 import com.fasterxml.jackson.annotation.JsonUnwrapped;
 
 /**
- * Value object used to carry information about the health information of a component or
- * subsystem.
+ * Carries information about the health of a component or subsystem.
  * <p>
  * {@link Health} contains a {@link Status} to express the state of a component or
  * subsystem and some additional details to carry some contextual information.
@@ -39,92 +38,162 @@ import com.fasterxml.jackson.annotation.JsonUnwrapped;
  * in a {@link HealthIndicator} would be:
  * 
  * <pre class="code">
- * Health health = new Health();
  * try {
  * 	// do some test to determine state of component
- * 	health.up().withDetail(&quot;version&quot;, &quot;1.1.2&quot;);
+ * 	return Health.up(&quot;version&quot;, &quot;1.1.2&quot;);
  * }
  * catch (Exception ex) {
- * 	health.down().withException(ex);
+ * 	return Health.down(ex);
  * }
- * return health;
  * </pre>
  * 
  * @author Christian Dupuis
+ * @author Phillip Webb
  * @since 1.1.0
  */
 @JsonInclude(Include.NON_EMPTY)
-public class Health {
+public final class Health {
 
-	private Status status;
+	private static final Map<String, Object> NO_DETAILS = Collections
+			.<String, Object> emptyMap();
 
-	private Map<String, Object> details;
+	private final Status status;
 
-	public Health() {
-		this(Status.UNKNOWN);
-	}
+	private final Map<String, Object> details;
 
-	public Health(Status status) {
+	/**
+	 * Create a new {@link Health} instance with the specified status and details.
+	 * @param status the status
+	 * @param details the details or {@code null}
+	 */
+	public Health(Status status, Map<String, ?> details) {
+		Assert.notNull(status, "Status must not be null");
 		this.status = status;
-		this.details = new LinkedHashMap<String, Object>();
+		this.details = Collections.unmodifiableMap(details == null ? NO_DETAILS
+				: new LinkedHashMap<String, Object>(details));
 	}
 
-	public Health status(Status status) {
-		Assert.notNull(status, "Status must not be null");
-		this.status = status;
-		return this;
+	/**
+	 * @return the status of the health (never {@code null})
+	 */
+	@JsonUnwrapped
+	public Status getStatus() {
+		return this.status;
 	}
 
-	public Health up() {
-		return status(Status.UP);
+	/**
+	 * @return the details of the health or an empty map.
+	 */
+	@JsonAnyGetter
+	public Map<String, Object> getDetails() {
+		return this.details;
 	}
 
-	public Health down() {
-		return status(Status.DOWN);
+	@Override
+	public boolean equals(Object obj) {
+		if (obj == this) {
+			return true;
+		}
+		if (obj != null && obj instanceof Health) {
+			Health other = (Health) obj;
+			return this.status.equals(other.status) && this.details.equals(other.details);
+		}
+		return false;
+	}
+
+	@Override
+	public int hashCode() {
+		int hashCode = this.status.hashCode();
+		return 13 * hashCode + this.details.hashCode();
+	}
+
+	@Override
+	public String toString() {
+		return getStatus() + " " + getDetails();
 	}
 
+	/**
+	 * Create a new {@link Health} object from this one, containing an additional
+	 * exception detail.
+	 * @param ex the exception
+	 * @return a new {@link Health} instance
+	 */
 	public Health withException(Exception ex) {
 		Assert.notNull(ex, "Exception must not be null");
 		return withDetail("error", ex.getClass().getName() + ": " + ex.getMessage());
 	}
 
+	/**
+	 * Create a new {@link Health} object from this one, containing an additional detail.
+	 * @param key the detail key
+	 * @param data the detail data
+	 * @return a new {@link Health} instance
+	 */
 	@JsonAnySetter
 	public Health withDetail(String key, Object data) {
 		Assert.notNull(key, "Key must not be null");
 		Assert.notNull(data, "Data must not be null");
-		this.details.put(key, data);
-		return this;
+		Map<String, Object> details = new LinkedHashMap<String, Object>(this.details);
+		details.put(key, data);
+		return new Health(this.status, details);
 	}
 
-	@JsonUnwrapped
-	public Status getStatus() {
-		return this.status;
+	/**
+	 * Create a new {@link Health} instance with an {@link Status#UNKNOWN} status.
+	 * @return a new {@link Health} instance
+	 */
+	public static Health unknown() {
+		return status(Status.UNKNOWN);
 	}
 
-	@JsonAnyGetter
-	public Map<String, Object> getDetails() {
-		return this.details;
+	/**
+	 * Create a new {@link Health} instance with an {@link Status#UP} status.
+	 * @return a new {@link Health} instance
+	 */
+	public static Health up() {
+		return status(Status.UP);
 	}
 
-	@Override
-	public boolean equals(Object obj) {
-		if (obj == this) {
-			return true;
+	/**
+	 * Create a new {@link Health} instance with an {@link Status#DOWN} status an the
+	 * specified exception details.
+	 * @param ex the exception
+	 * @return a new {@link Health} instance
+	 */
+	public static Health down(Exception ex) {
+		return down().withException(ex);
 	}
-		if (obj != null && obj instanceof Health) {
-			return ObjectUtils.nullSafeEquals(this.status, ((Health) obj).status)
-					&& ObjectUtils.nullSafeEquals(this.details, ((Health) obj).details);
+
+	/**
+	 * Create a new {@link Health} instance with a {@link Status#DOWN} status.
+	 * @return a new {@link Health} instance
+	 */
+	public static Health down() {
+		return status(Status.DOWN);
 	}
-		return false;
+
+	/**
+	 * Create a new {@link Health} instance with an {@link Status#OUT_OF_SERVICE} status.
+	 * @return a new {@link Health} instance
+	 */
+	public static Health outOfService() {
+		return status(Status.OUT_OF_SERVICE);
 	}
 
-	@Override
-	public int hashCode() {
-		int hashCode = 0;
-		if (this.status != null) {
-			hashCode = this.status.hashCode();
+	/**
+	 * Create a new {@link Health} instance with a specific status code.
+	 * @return a new {@link Health} instance
+	 */
+	public static Health status(String statusCode) {
+		return status(new Status(statusCode));
 	}
-		return 13 * hashCode + this.details.hashCode();
+
+	/**
+	 * Create a new {@link Health} instance with a specific {@link Status}.
+	 * @return a new {@link Health} instance
+	 */
+	public static Health status(Status status) {
+		return new Health(status, null);
 	}
 
 }

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/MongoHealthIndicator.java

@@ -38,9 +38,9 @@ public class MongoHealthIndicator extends AbstractHealthIndicator {
 	}
 
 	@Override
-	protected void doHealthCheck(Health health) throws Exception {
+	protected Health doHealthCheck() throws Exception {
 		CommandResult result = this.mongoTemplate.executeCommand("{ serverStatus: 1 }");
-		health.up().withDetail("version", result.getString("version"));
+		return Health.up().withDetail("version", result.getString("version"));
 	}
 
 }

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/OrderedHealthAggregator.java

@@ -66,14 +66,14 @@ public class OrderedHealthAggregator extends AbstractHealthAggregator {
 	}
 
 	@Override
-	protected Status aggregateStatus(List<Status> status) {
+	protected Status aggregateStatus(List<Status> candidates) {
 		// If no status is given return UNKNOWN
-		if (status.size() == 0) {
+		if (candidates.size() == 0) {
 			return Status.UNKNOWN;
 		}
 		// Sort given Status instances by configured order
-		Collections.sort(status, new StatusComparator(this.statusOrder));
-		return status.get(0);
+		Collections.sort(candidates, new StatusComparator(this.statusOrder));
+		return candidates.get(0);
 	}
 
 	/**

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/RabbitHealthIndicator.java

@@ -41,17 +41,19 @@ public class RabbitHealthIndicator extends AbstractHealthIndicator {
 	}
 
 	@Override
-	protected void doHealthCheck(Health health) throws Exception {
-		health.up().withDetail("version",
-				this.rabbitTemplate.execute(new ChannelCallback<String>() {
+	protected Health doHealthCheck() throws Exception {
+		return Health.up().withDetail("version", getVersion());
+	}
 
+	private String getVersion() {
+		return this.rabbitTemplate.execute(new ChannelCallback<String>() {
 			@Override
 			public String doInRabbit(Channel channel) throws Exception {
 				Map<String, Object> serverProperties = channel.getConnection()
 						.getServerProperties();
 				return serverProperties.get("version").toString();
 			}
-				}));
+		});
 	}
 
 }

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/RedisHealthIndicator.java

@@ -40,12 +40,12 @@ public class RedisHealthIndicator extends AbstractHealthIndicator {
 	}
 
 	@Override
-	protected void doHealthCheck(Health health) throws Exception {
-		RedisConnection connection = null;
+	protected Health doHealthCheck() throws Exception {
+		RedisConnection connection = RedisConnectionUtils
+				.getConnection(this.redisConnectionFactory);
 		try {
-			connection = RedisConnectionUtils.getConnection(this.redisConnectionFactory);
 			Properties info = connection.info();
-			health.up().withDetail("version", info.getProperty("redis_version"));
+			return Health.up().withDetail("version", info.getProperty("redis_version"));
 		}
 		finally {
 			RedisConnectionUtils.releaseConnection(connection,

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/SimpleDataSourceHealthIndicator.java

@@ -35,7 +35,7 @@ import org.springframework.util.StringUtils;
  * @author Dave Syer
  * @author Christian Dupuis
  */
-public class SimpleDataSourceHealthIndicator implements HealthIndicator {
+public class SimpleDataSourceHealthIndicator extends AbstractHealthIndicator {
 
 	private DataSource dataSource;
 
@@ -63,7 +63,6 @@ public class SimpleDataSourceHealthIndicator implements HealthIndicator {
 	/**
 	 * Create a new {@link SimpleDataSourceHealthIndicator} using the specified
 	 * datasource.
-	 * 
 	 * @param dataSource the data source
 	 */
 	public SimpleDataSourceHealthIndicator(DataSource dataSource) {
@@ -72,40 +71,39 @@ public class SimpleDataSourceHealthIndicator implements HealthIndicator {
 	}
 
 	@Override
-	public Health health() {
-		Health health = new Health();
-		health.up();
-
-		String product = "unknown";
-		if (this.dataSource != null) {
-			try {
-				product = this.jdbcTemplate.execute(new ConnectionCallback<String>() {
-
-					@Override
-					public String doInConnection(Connection connection)
-							throws SQLException, DataAccessException {
-						return connection.getMetaData().getDatabaseProductName();
-					}
-				});
-				health.withDetail("database", product);
+	protected Health doHealthCheck() throws Exception {
+		if (this.dataSource == null) {
+			return Health.up().withDetail("database", "unknown");
 		}
-			catch (DataAccessException ex) {
-				health.down().withException(ex);
+		return doDataSourceHealthCheck();
 	}
+
+	private Health doDataSourceHealthCheck() throws Exception {
+		String product = getProduct();
+		Health health = Health.up().withDetail("database", product);
 		String query = detectQuery(product);
 		if (StringUtils.hasText(query)) {
 			try {
-					health.withDetail("hello",
+				health = health.withDetail("hello",
 						this.jdbcTemplate.queryForObject(query, Object.class));
 			}
 			catch (Exception ex) {
-					health.down().withException(ex);
-				}
+				return Health.down().withDetail("database", product).withException(ex);
 			}
 		}
 		return health;
 	}
 
+	private String getProduct() {
+		return this.jdbcTemplate.execute(new ConnectionCallback<String>() {
+			@Override
+			public String doInConnection(Connection connection) throws SQLException,
+					DataAccessException {
+				return connection.getMetaData().getDatabaseProductName();
+			}
+		});
+	}
+
 	protected String detectQuery(String product) {
 		String query = this.query;
 		if (!StringUtils.hasText(query)) {

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/SolrHealthIndicator.java

@@ -33,9 +33,9 @@ public class SolrHealthIndicator extends AbstractHealthIndicator {
 	}
 
 	@Override
-	protected void doHealthCheck(Health health) throws Exception {
-		this.solrServer.ping();
-		health.up().withDetail("solrStatus",
-				this.solrServer.ping().getResponse().get("status"));
+	protected Health doHealthCheck() throws Exception {
+		Object status = this.solrServer.ping().getResponse().get("status");
+		return Health.up().withDetail("solrStatus", status);
 	}
+
 }

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/Status.java

@@ -35,7 +35,7 @@ import com.fasterxml.jackson.annotation.JsonProperty;
  * @since 1.1.0
  */
 @JsonInclude(Include.NON_EMPTY)
-public class Status {
+public final class Status {
 
 	/**
 	 * Convenient constant value representing unknown state

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/VanillaHealthIndicator.java

@@ -25,8 +25,8 @@ package org.springframework.boot.actuate.health;
 public class VanillaHealthIndicator extends AbstractHealthIndicator {
 
 	@Override
-	protected void doHealthCheck(Health health) throws Exception {
-		health.up();
+	protected Health doHealthCheck() throws Exception {
+		return Health.up();
 	}
 
 }

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/HealthEndpointTests.java

@@ -65,7 +65,7 @@ public class HealthEndpointTests extends AbstractEndpointTests<HealthEndpoint> {
 
 				@Override
 				public Health health() {
-					return new Health().status(new Status("FINE"));
+					return Health.status("FINE");
 				}
 			};
 		}

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/mvc/HealthMvcEndpointTests.java

@@ -51,7 +51,7 @@ public class HealthMvcEndpointTests {
 
 	@Test
 	public void up() {
-		when(this.endpoint.invoke()).thenReturn(new Health().up());
+		when(this.endpoint.invoke()).thenReturn(Health.up());
 		Object result = this.mvc.invoke();
 		assertTrue(result instanceof Health);
 		assertTrue(((Health) result).getStatus() == Status.UP);
@@ -60,7 +60,7 @@ public class HealthMvcEndpointTests {
 	@SuppressWarnings("unchecked")
 	@Test
 	public void down() {
-		when(this.endpoint.invoke()).thenReturn(new Health().down());
+		when(this.endpoint.invoke()).thenReturn(Health.down());
 		Object result = this.mvc.invoke();
 		assertTrue(result instanceof ResponseEntity);
 		ResponseEntity<Health> response = (ResponseEntity<Health>) result;
@@ -71,7 +71,7 @@ public class HealthMvcEndpointTests {
 	@SuppressWarnings("unchecked")
 	@Test
 	public void customMapping() {
-		when(this.endpoint.invoke()).thenReturn(new Health().status(new Status("OK")));
+		when(this.endpoint.invoke()).thenReturn(Health.status("OK"));
 		this.mvc.setStatusMapping(Collections.singletonMap("OK",
 				HttpStatus.INTERNAL_SERVER_ERROR));
 		Object result = this.mvc.invoke();

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/health/CompositeHealthIndicatorTests.java

@@ -55,9 +55,9 @@ public class CompositeHealthIndicatorTests {
 	@Before
 	public void setup() {
 		MockitoAnnotations.initMocks(this);
-		given(this.one.health()).willReturn(new Health().withDetail("1", "1"));
-		given(this.two.health()).willReturn(new Health().withDetail("2", "2"));
-		given(this.three.health()).willReturn(new Health().withDetail("3", "3"));
+		given(this.one.health()).willReturn(Health.unknown().withDetail("1", "1"));
+		given(this.two.health()).willReturn(Health.unknown().withDetail("2", "2"));
+		given(this.three.health()).willReturn(Health.unknown().withDetail("3", "3"));
 
 		this.healthAggregator = new OrderedHealthAggregator();
 	}
@@ -72,9 +72,9 @@ public class CompositeHealthIndicatorTests {
 		Health result = composite.health();
 		assertThat(result.getDetails().size(), equalTo(2));
 		assertThat(result.getDetails(),
-				hasEntry("one", (Object) new Health().withDetail("1", "1")));
+				hasEntry("one", (Object) Health.unknown().withDetail("1", "1")));
 		assertThat(result.getDetails(),
-				hasEntry("two", (Object) new Health().withDetail("2", "2")));
+				hasEntry("two", (Object) Health.unknown().withDetail("2", "2")));
 	}
 
 	@Test
@@ -88,11 +88,11 @@ public class CompositeHealthIndicatorTests {
 		Health result = composite.health();
 		assertThat(result.getDetails().size(), equalTo(3));
 		assertThat(result.getDetails(),
-				hasEntry("one", (Object) new Health().withDetail("1", "1")));
+				hasEntry("one", (Object) Health.unknown().withDetail("1", "1")));
 		assertThat(result.getDetails(),
-				hasEntry("two", (Object) new Health().withDetail("2", "2")));
+				hasEntry("two", (Object) Health.unknown().withDetail("2", "2")));
 		assertThat(result.getDetails(),
-				hasEntry("three", (Object) new Health().withDetail("3", "3")));
+				hasEntry("three", (Object) Health.unknown().withDetail("3", "3")));
 	}
 
 	@Test
@@ -104,9 +104,9 @@ public class CompositeHealthIndicatorTests {
 		Health result = composite.health();
 		assertThat(result.getDetails().size(), equalTo(2));
 		assertThat(result.getDetails(),
-				hasEntry("one", (Object) new Health().withDetail("1", "1")));
+				hasEntry("one", (Object) Health.unknown().withDetail("1", "1")));
 		assertThat(result.getDetails(),
-				hasEntry("two", (Object) new Health().withDetail("2", "2")));
+				hasEntry("two", (Object) Health.unknown().withDetail("2", "2")));
 	}
 
 	@Test

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/health/HealthTests.java

+/*
+ * Copyright 2012-2014 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
+ *
+ *      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.springframework.boot.actuate.health;
+
+import java.util.Collections;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.not;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Tests for {@link Health}.
+ * 
+ * @author Phillip Webb
+ */
+public class HealthTests {
+
+	@Rule
+	public ExpectedException thrown = ExpectedException.none();
+
+	@Test
+	public void statusMustNotBeNull() throws Exception {
+		this.thrown.expect(IllegalArgumentException.class);
+		this.thrown.expectMessage("Status must not be null");
+		new Health(null, null);
+	}
+
+	@Test
+	public void createWithStatus() throws Exception {
+		Health health = new Health(Status.UP, null);
+		assertThat(health.getStatus(), equalTo(Status.UP));
+		assertThat(health.getDetails().size(), equalTo(0));
+	}
+
+	@Test
+	public void createWithDetails() throws Exception {
+		Health health = new Health(Status.UP, Collections.singletonMap("a", "b"));
+		assertThat(health.getStatus(), equalTo(Status.UP));
+		assertThat(health.getDetails().get("a"), equalTo((Object) "b"));
+	}
+
+	@Test
+	public void equalsAndHashCode() throws Exception {
+		Health h1 = new Health(Status.UP, Collections.singletonMap("a", "b"));
+		Health h2 = new Health(Status.UP, Collections.singletonMap("a", "b"));
+		Health h3 = new Health(Status.UP, null);
+		assertThat(h1, equalTo(h1));
+		assertThat(h1, equalTo(h2));
+		assertThat(h1, not(equalTo(h3)));
+		assertThat(h1.hashCode(), equalTo(h1.hashCode()));
+		assertThat(h1.hashCode(), equalTo(h2.hashCode()));
+		assertThat(h1.hashCode(), not(equalTo(h3.hashCode())));
+	}
+
+	@Test
+	public void withException() throws Exception {
+		RuntimeException ex = new RuntimeException("bang");
+		Health health = new Health(Status.UP, Collections.singletonMap("a", "b"))
+				.withException(ex);
+		assertThat(health.getDetails().get("a"), equalTo((Object) "b"));
+		assertThat(health.getDetails().get("error"),
+				equalTo((Object) "java.lang.RuntimeException: bang"));
+	}
+
+	@Test
+	public void withDetails() throws Exception {
+		Health health = new Health(Status.UP, Collections.singletonMap("a", "b"))
+				.withDetail("c", "d");
+		assertThat(health.getDetails().get("a"), equalTo((Object) "b"));
+		assertThat(health.getDetails().get("c"), equalTo((Object) "d"));
+	}
+
+	@Test
+	public void unknownWithDetails() throws Exception {
+		Health health = Health.unknown().withDetail("a", "b");
+		assertThat(health.getStatus(), equalTo(Status.UNKNOWN));
+		assertThat(health.getDetails().get("a"), equalTo((Object) "b"));
+	}
+
+	@Test
+	public void unknown() throws Exception {
+		Health health = Health.unknown();
+		assertThat(health.getStatus(), equalTo(Status.UNKNOWN));
+		assertThat(health.getDetails().size(), equalTo(0));
+	}
+
+	@Test
+	public void upWithDetails() throws Exception {
+		Health health = Health.up().withDetail("a", "b");
+		assertThat(health.getStatus(), equalTo(Status.UP));
+		assertThat(health.getDetails().get("a"), equalTo((Object) "b"));
+	}
+
+	@Test
+	public void up() throws Exception {
+		Health health = Health.up();
+		assertThat(health.getStatus(), equalTo(Status.UP));
+		assertThat(health.getDetails().size(), equalTo(0));
+	}
+
+	@Test
+	public void downWithException() throws Exception {
+		RuntimeException ex = new RuntimeException("bang");
+		Health health = Health.down(ex);
+		assertThat(health.getStatus(), equalTo(Status.DOWN));
+		assertThat(health.getDetails().get("error"),
+				equalTo((Object) "java.lang.RuntimeException: bang"));
+	}
+
+	@Test
+	public void down() throws Exception {
+		Health health = Health.down();
+		assertThat(health.getStatus(), equalTo(Status.DOWN));
+		assertThat(health.getDetails().size(), equalTo(0));
+	}
+
+	@Test
+	public void outOfService() throws Exception {
+		Health health = Health.outOfService();
+		assertThat(health.getStatus(), equalTo(Status.OUT_OF_SERVICE));
+		assertThat(health.getDetails().size(), equalTo(0));
+	}
+
+	@Test
+	public void statusCode() throws Exception {
+		Health health = Health.status("UP");
+		assertThat(health.getStatus(), equalTo(Status.UP));
+		assertThat(health.getDetails().size(), equalTo(0));
+	}
+
+	@Test
+	public void status() throws Exception {
+		Health health = Health.status(Status.UP);
+		assertThat(health.getStatus(), equalTo(Status.UP));
+		assertThat(health.getDetails().size(), equalTo(0));
+	}
+
+}

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/health/OrderedHealthAggregatorTests.java

@@ -42,10 +42,10 @@ public class OrderedHealthAggregatorTests {
 	@Test
 	public void defaultOrder() {
 		Map<String, Health> healths = new HashMap<String, Health>();
-		healths.put("h1", new Health(Status.DOWN));
-		healths.put("h2", new Health(Status.UP));
-		healths.put("h3", new Health(Status.UNKNOWN));
-		healths.put("h4", new Health(Status.OUT_OF_SERVICE));
+		healths.put("h1", Health.status(Status.DOWN));
+		healths.put("h2", Health.status(Status.UP));
+		healths.put("h3", Health.status(Status.UNKNOWN));
+		healths.put("h4", Health.status(Status.OUT_OF_SERVICE));
 		assertEquals(Status.DOWN, this.healthAggregator.aggregate(healths).getStatus());
 	}
 
@@ -54,21 +54,21 @@ public class OrderedHealthAggregatorTests {
 		this.healthAggregator.setStatusOrder(Status.UNKNOWN, Status.UP,
 				Status.OUT_OF_SERVICE, Status.DOWN);
 		Map<String, Health> healths = new HashMap<String, Health>();
-		healths.put("h1", new Health(Status.DOWN));
-		healths.put("h2", new Health(Status.UP));
-		healths.put("h3", new Health(Status.UNKNOWN));
-		healths.put("h4", new Health(Status.OUT_OF_SERVICE));
+		healths.put("h1", Health.status(Status.DOWN));
+		healths.put("h2", Health.status(Status.UP));
+		healths.put("h3", Health.status(Status.UNKNOWN));
+		healths.put("h4", Health.status(Status.OUT_OF_SERVICE));
 		assertEquals(Status.UNKNOWN, this.healthAggregator.aggregate(healths).getStatus());
 	}
 
 	@Test
 	public void defaultOrderWithCustomStatus() {
 		Map<String, Health> healths = new HashMap<String, Health>();
-		healths.put("h1", new Health(Status.DOWN));
-		healths.put("h2", new Health(Status.UP));
-		healths.put("h3", new Health(Status.UNKNOWN));
-		healths.put("h4", new Health(Status.OUT_OF_SERVICE));
-		healths.put("h5", new Health(new Status("CUSTOM")));
+		healths.put("h1", Health.status(Status.DOWN));
+		healths.put("h2", Health.status(Status.UP));
+		healths.put("h3", Health.status(Status.UNKNOWN));
+		healths.put("h4", Health.status(Status.OUT_OF_SERVICE));
+		healths.put("h5", Health.status(new Status("CUSTOM")));
 		assertEquals(new Status("CUSTOM"), this.healthAggregator.aggregate(healths)
 				.getStatus());
 	}
@@ -78,11 +78,11 @@ public class OrderedHealthAggregatorTests {
 		this.healthAggregator.setStatusOrder(Arrays.asList("DOWN", "OUT_OF_SERVICE",
 				"UP", "UNKNOWN", "CUSTOM"));
 		Map<String, Health> healths = new HashMap<String, Health>();
-		healths.put("h1", new Health(Status.DOWN));
-		healths.put("h2", new Health(Status.UP));
-		healths.put("h3", new Health(Status.UNKNOWN));
-		healths.put("h4", new Health(Status.OUT_OF_SERVICE));
-		healths.put("h5", new Health(new Status("CUSTOM")));
+		healths.put("h1", Health.status(Status.DOWN));
+		healths.put("h2", Health.status(Status.UP));
+		healths.put("h3", Health.status(Status.UNKNOWN));
+		healths.put("h4", Health.status(Status.OUT_OF_SERVICE));
+		healths.put("h5", Health.status(new Status("CUSTOM")));
 		assertEquals(Status.DOWN, this.healthAggregator.aggregate(healths).getStatus());
 	}
 

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/health/SimpleDataSourceHealthIndicatorTests.java

@@ -27,8 +27,10 @@ import org.springframework.jdbc.core.JdbcTemplate;
 import org.springframework.jdbc.datasource.DriverManagerDataSource;
 import org.springframework.jdbc.datasource.SingleConnectionDataSource;
 
+import static org.hamcrest.Matchers.notNullValue;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertThat;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
@@ -78,7 +80,7 @@ public class SimpleDataSourceHealthIndicatorTests {
 		this.indicator.setDataSource(this.dataSource);
 		this.indicator.setQuery("SELECT COUNT(*) from BAR");
 		Health health = this.indicator.health();
-		assertNotNull(health.getDetails().get("database"));
+		assertThat(health.getDetails().get("database"), notNullValue());
 		assertEquals(Status.DOWN, health.getStatus());
 	}