Use Supplier<String> support in Assert in spring-test

This commit makes use of the new Supplier<String> variants of utility
methods in org.springframework.util.Assert within the spring-test
module.

Issue: SPR-14450

spring-test/src/main/java/org/springframework/mock/jndi/SimpleNamingContextBuilder.java

@@ -26,6 +26,7 @@ import javax.naming.spi.NamingManager;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -137,12 +138,10 @@ public class SimpleNamingContextBuilder implements InitialContextFactoryBuilder
 		logger.info("Activating simple JNDI environment");
 		synchronized (initializationLock) {
 			if (!initialized) {
-				if (NamingManager.hasInitialContextFactoryBuilder()) {
-					throw new IllegalStateException(
+				Assert.state(!NamingManager.hasInitialContextFactoryBuilder(),
 							"Cannot activate SimpleNamingContextBuilder: there is already a JNDI provider registered. " +
 							"Note that JNDI is a JVM-wide service, shared at the JVM system class loader level, " +
 							"with no reset option. As a consequence, a JNDI provider must only be registered once per JVM.");
-				}
 				NamingManager.setInitialContextFactoryBuilder(this);
 				initialized = true;
 			}

spring-test/src/main/java/org/springframework/mock/web/MockExpressionEvaluator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -20,6 +20,7 @@ import javax.servlet.jsp.JspException;
 import javax.servlet.jsp.PageContext;
 
 import org.apache.taglibs.standard.lang.support.ExpressionEvaluatorManager;
+import org.springframework.util.Assert;
 
 /**
  * Mock implementation of the JSP 2.0 {@link javax.servlet.jsp.el.ExpressionEvaluator}
@@ -68,9 +69,7 @@ public class MockExpressionEvaluator extends javax.servlet.jsp.el.ExpressionEval
 	public Object evaluate(String expression, Class expectedType, javax.servlet.jsp.el.VariableResolver variableResolver,
 			javax.servlet.jsp.el.FunctionMapper functionMapper) throws javax.servlet.jsp.el.ELException {
 
-		if (variableResolver != null) {
-			throw new IllegalArgumentException("Custom VariableResolver not supported");
-		}
+		Assert.isNull(variableResolver, "Custom VariableResolver not supported");
 		return doEvaluate(expression, expectedType, functionMapper);
 	}
 
@@ -78,9 +77,7 @@ public class MockExpressionEvaluator extends javax.servlet.jsp.el.ExpressionEval
 	protected Object doEvaluate(String expression, Class expectedType, javax.servlet.jsp.el.FunctionMapper functionMapper)
 			throws javax.servlet.jsp.el.ELException {
 
-		if (functionMapper != null) {
-			throw new IllegalArgumentException("Custom FunctionMapper not supported");
-		}
+		Assert.isNull(functionMapper, "Custom FunctionMapper not supported");
 		try {
 			return ExpressionEvaluatorManager.evaluate("JSP EL expression", expression, expectedType, this.pageContext);
 		}

spring-test/src/main/java/org/springframework/mock/web/MockFilterChain.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -120,10 +120,7 @@ public class MockFilterChain implements FilterChain {
 	public void doFilter(ServletRequest request, ServletResponse response) throws IOException, ServletException {
 		Assert.notNull(request, "Request must not be null");
 		Assert.notNull(response, "Response must not be null");
-
-		if (this.request != null) {
-			 throw new IllegalStateException("This FilterChain has already been called!");
-		}
+		Assert.state(this.request == null, "This FilterChain has already been called!");
 
 		if (this.iterator == null) {
 			this.iterator = this.filters.iterator();

spring-test/src/main/java/org/springframework/mock/web/MockHttpServletRequest.java

@@ -328,9 +328,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	 * throwing an IllegalStateException if not active anymore.
 	 */
 	protected void checkActive() throws IllegalStateException {
-		if (!this.active) {
-			throw new IllegalStateException("Request is not active anymore");
-		}
+		Assert.state(this.active, "Request is not active anymore");
 	}
 
 
@@ -807,9 +805,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 
 	@Override
 	public AsyncContext startAsync(ServletRequest request, ServletResponse response) {
-		if (!this.asyncSupported) {
-			throw new IllegalStateException("Async not supported");
-		}
+		Assert.state(this.asyncSupported, "Async not supported");
 		this.asyncStarted = true;
 		this.asyncContext = new MockAsyncContext(request, response);
 		return this.asyncContext;

spring-test/src/main/java/org/springframework/mock/web/MockHttpServletResponse.java

@@ -181,17 +181,13 @@ public class MockHttpServletResponse implements HttpServletResponse {
 
 	@Override
 	public ServletOutputStream getOutputStream() {
-		if (!this.outputStreamAccessAllowed) {
-			throw new IllegalStateException("OutputStream access not allowed");
-		}
+		Assert.state(this.outputStreamAccessAllowed, "OutputStream access not allowed");
 		return this.outputStream;
 	}
 
 	@Override
 	public PrintWriter getWriter() throws UnsupportedEncodingException {
-		if (!this.writerAccessAllowed) {
-			throw new IllegalStateException("Writer access not allowed");
-		}
+		Assert.state(this.writerAccessAllowed, "Writer access not allowed");
 		if (this.writer == null) {
 			Writer targetWriter = (this.characterEncoding != null ?
 					new OutputStreamWriter(this.content, this.characterEncoding) : new OutputStreamWriter(this.content));
@@ -275,9 +271,7 @@ public class MockHttpServletResponse implements HttpServletResponse {
 
 	@Override
 	public void resetBuffer() {
-		if (isCommitted()) {
-			throw new IllegalStateException("Cannot reset buffer - response is already committed");
-		}
+		Assert.state(!isCommitted(), "Cannot reset buffer - response is already committed");
 		this.content.reset();
 	}
 
@@ -456,9 +450,7 @@ public class MockHttpServletResponse implements HttpServletResponse {
 
 	@Override
 	public void sendError(int status, String errorMessage) throws IOException {
-		if (isCommitted()) {
-			throw new IllegalStateException("Cannot set error status - response is already committed");
-		}
+		Assert.state(!isCommitted(), "Cannot set error status - response is already committed");
 		this.status = status;
 		this.errorMessage = errorMessage;
 		setCommitted(true);
@@ -466,18 +458,14 @@ public class MockHttpServletResponse implements HttpServletResponse {
 
 	@Override
 	public void sendError(int status) throws IOException {
-		if (isCommitted()) {
-			throw new IllegalStateException("Cannot set error status - response is already committed");
-		}
+		Assert.state(!isCommitted(), "Cannot set error status - response is already committed");
 		this.status = status;
 		setCommitted(true);
 	}
 
 	@Override
 	public void sendRedirect(String url) throws IOException {
-		if (isCommitted()) {
-			throw new IllegalStateException("Cannot send redirect - response is already committed");
-		}
+		Assert.state(!isCommitted(), "Cannot send redirect - response is already committed");
 		Assert.notNull(url, "Redirect URL must not be null");
 		setHeader(LOCATION_HEADER, url);
 		setStatus(HttpServletResponse.SC_MOVED_TEMPORARILY);
@@ -627,10 +615,8 @@ public class MockHttpServletResponse implements HttpServletResponse {
 
 	public String getIncludedUrl() {
 		int count = this.includedUrls.size();
-		if (count > 1) {
-			throw new IllegalStateException(
-					"More than 1 URL included - check getIncludedUrls instead: " + this.includedUrls);
-		}
+		Assert.state(count <= 1,
+				() -> "More than 1 URL included - check getIncludedUrls instead: " + this.includedUrls);
 		return (count == 1 ? this.includedUrls.get(0) : null);
 	}
 

spring-test/src/main/java/org/springframework/mock/web/MockHttpSession.java

@@ -248,9 +248,7 @@ public class MockHttpSession implements HttpSession {
 	 * @throws IllegalStateException if this session has been invalidated
 	 */
 	private void assertIsValid() {
-		if (isInvalid()) {
-			throw new IllegalStateException("The session has already been invalidated");
-		}
+		Assert.state(!isInvalid(), "The session has already been invalidated");
 	}
 
 	public void setNew(boolean value) {

spring-test/src/main/java/org/springframework/mock/web/MockRequestDispatcher.java

@@ -59,9 +59,7 @@ public class MockRequestDispatcher implements RequestDispatcher {
 	public void forward(ServletRequest request, ServletResponse response) {
 		Assert.notNull(request, "Request must not be null");
 		Assert.notNull(response, "Response must not be null");
-		if (response.isCommitted()) {
-			throw new IllegalStateException("Cannot perform forward - response is already committed");
-		}
+		Assert.state(!response.isCommitted(), "Cannot perform forward - response is already committed");
 		getMockHttpServletResponse(response).setForwardedUrl(this.resource);
 		if (logger.isDebugEnabled()) {
 			logger.debug("MockRequestDispatcher: forwarding to [" + this.resource + "]");

spring-test/src/main/java/org/springframework/mock/web/MockServletContext.java

@@ -355,9 +355,8 @@ public class MockServletContext implements ServletContext {
 
 	@Override
 	public RequestDispatcher getRequestDispatcher(String path) {
-		if (!path.startsWith("/")) {
-			throw new IllegalArgumentException("RequestDispatcher path at ServletContext level must start with '/'");
-		}
+		Assert.isTrue(path.startsWith("/"),
+				() -> "RequestDispatcher path [" + path + "] at ServletContext level must start with '/'");
 		return new MockRequestDispatcher(path);
 	}
 

spring-test/src/main/java/org/springframework/test/annotation/ProfileValueUtils.java

@@ -184,10 +184,8 @@ public abstract class ProfileValueUtils {
 		String environmentValue = profileValueSource.get(ifProfileValue.name());
 		String[] annotatedValues = ifProfileValue.values();
 		if (StringUtils.hasLength(ifProfileValue.value())) {
-			if (annotatedValues.length > 0) {
-				throw new IllegalArgumentException("Setting both the 'value' and 'values' attributes " +
+			Assert.isTrue(annotatedValues.length == 0, () -> "Setting both the 'value' and 'values' attributes " +
 						"of @IfProfileValue is not allowed: choose one or the other.");
-			}
 			annotatedValues = new String[] { ifProfileValue.value() };
 		}
 

spring-test/src/main/java/org/springframework/test/context/BootstrapUtils.java

@@ -25,6 +25,7 @@ import org.apache.commons.logging.LogFactory;
 import org.springframework.beans.BeanUtils;
 import org.springframework.core.annotation.AnnotatedElementUtils;
 import org.springframework.core.annotation.AnnotationAttributes;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -151,11 +152,9 @@ abstract class BootstrapUtils {
 		if (annotations.size() < 1) {
 			return null;
 		}
-		if (annotations.size() > 1) {
-			throw new IllegalStateException(String.format(
+		Assert.state(annotations.size() <= 1, () -> String.format(
 				"Configuration error: found multiple declarations of @BootstrapWith for test class [%s]: %s",
 				testClass.getName(), annotations));
-		}
 		return annotations.iterator().next().value();
 	}
 

spring-test/src/main/java/org/springframework/test/context/jdbc/SqlScriptsTestExecutionListener.java

@@ -43,6 +43,7 @@ import org.springframework.transaction.TransactionDefinition;
 import org.springframework.transaction.interceptor.DefaultTransactionAttribute;
 import org.springframework.transaction.interceptor.TransactionAttribute;
 import org.springframework.transaction.support.TransactionTemplate;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.ReflectionUtils;
@@ -201,16 +202,12 @@ public class SqlScriptsTestExecutionListener extends AbstractTestExecutionListen
 		final boolean newTxRequired = mergedSqlConfig.getTransactionMode() == TransactionMode.ISOLATED;
 
 		if (transactionManager == null) {
-			if (newTxRequired) {
-				throw new IllegalStateException(String.format("Failed to execute SQL scripts for test context %s: "
-						+ "cannot execute SQL scripts using Transaction Mode "
-						+ "[%s] without a PlatformTransactionManager.", testContext, TransactionMode.ISOLATED));
-			}
+			Assert.state(!newTxRequired, () -> String.format("Failed to execute SQL scripts for test context %s: " +
+					"cannot execute SQL scripts using Transaction Mode " +
+					"[%s] without a PlatformTransactionManager.", testContext, TransactionMode.ISOLATED));
 
-			if (dataSource == null) {
-				throw new IllegalStateException(String.format("Failed to execute SQL scripts for test context %s: "
-						+ "supply at least a DataSource or PlatformTransactionManager.", testContext));
-			}
+			Assert.state(dataSource != null, () -> String.format("Failed to execute SQL scripts for test context %s: " +
+					"supply at least a DataSource or PlatformTransactionManager.", testContext));
 
 			// Execute scripts directly against the DataSource
 			populator.execute(dataSource);
@@ -228,11 +225,9 @@ public class SqlScriptsTestExecutionListener extends AbstractTestExecutionListen
 
 			if (dataSource == null) {
 				dataSource = dataSourceFromTxMgr;
-				if (dataSource == null) {
-					throw new IllegalStateException(String.format("Failed to execute SQL scripts for test context %s: "
-							+ "could not obtain DataSource from transaction manager [%s] (named '%s').", testContext,
+				Assert.state(dataSource != null, () -> String.format("Failed to execute SQL scripts for test context %s: " +
+						"could not obtain DataSource from transaction manager [%s] (named '%s').", testContext,
 						transactionManager.getClass().getName(), tmName));
-				}
 			}
 
 			final DataSource finalDataSource = dataSource;

spring-test/src/main/java/org/springframework/test/context/junit4/SpringJUnit4ClassRunner.java

@@ -49,6 +49,7 @@ import org.springframework.test.context.junit4.statements.RunBeforeTestExecution
 import org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks;
 import org.springframework.test.context.junit4.statements.SpringFailOnTimeout;
 import org.springframework.test.context.junit4.statements.SpringRepeat;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ReflectionUtils;
 
@@ -100,15 +101,12 @@ public class SpringJUnit4ClassRunner extends BlockJUnit4ClassRunner {
 	private static final Method withRulesMethod;
 
 	static {
-		if (!ClassUtils.isPresent("org.junit.internal.Throwables", SpringJUnit4ClassRunner.class.getClassLoader())) {
-			throw new IllegalStateException("SpringJUnit4ClassRunner requires JUnit 4.12 or higher.");
-		}
+		Assert.state(ClassUtils.isPresent("org.junit.internal.Throwables", SpringJUnit4ClassRunner.class.getClassLoader()),
+				"SpringJUnit4ClassRunner requires JUnit 4.12 or higher.");
 
 		withRulesMethod = ReflectionUtils.findMethod(SpringJUnit4ClassRunner.class, "withRules",
 				FrameworkMethod.class, Object.class, Statement.class);
-		if (withRulesMethod == null) {
-			throw new IllegalStateException("SpringJUnit4ClassRunner requires JUnit 4.12 or higher.");
-		}
+		Assert.state(withRulesMethod != null, "SpringJUnit4ClassRunner requires JUnit 4.12 or higher.");
 		ReflectionUtils.makeAccessible(withRulesMethod);
 	}
 
@@ -118,14 +116,12 @@ public class SpringJUnit4ClassRunner extends BlockJUnit4ClassRunner {
 
 	private static void ensureSpringRulesAreNotPresent(Class<?> testClass) {
 		for (Field field : testClass.getFields()) {
-			if (SpringClassRule.class.isAssignableFrom(field.getType())) {
-				throw new IllegalStateException(String.format("Detected SpringClassRule field in test class [%s], " +
-						"but SpringClassRule cannot be used with the SpringJUnit4ClassRunner.", testClass.getName()));
-			}
-			if (SpringMethodRule.class.isAssignableFrom(field.getType())) {
-				throw new IllegalStateException(String.format("Detected SpringMethodRule field in test class [%s], " +
-						"but SpringMethodRule cannot be used with the SpringJUnit4ClassRunner.", testClass.getName()));
-			}
+			Assert.state(!SpringClassRule.class.isAssignableFrom(field.getType()), () -> String.format(
+					"Detected SpringClassRule field in test class [%s], " +
+					"but SpringClassRule cannot be used with the SpringJUnit4ClassRunner.", testClass.getName()));
+			Assert.state(!SpringMethodRule.class.isAssignableFrom(field.getType()), () -> String.format(
+					"Detected SpringMethodRule field in test class [%s], " +
+					"but SpringMethodRule cannot be used with the SpringJUnit4ClassRunner.", testClass.getName()));
 		}
 	}
 

spring-test/src/main/java/org/springframework/test/context/junit4/rules/SpringClassRule.java

@@ -98,9 +98,8 @@ public class SpringClassRule implements TestRule {
 			new ConcurrentHashMap<>(64);
 
 	static {
-		if (!ClassUtils.isPresent("org.junit.internal.Throwables", SpringClassRule.class.getClassLoader())) {
-			throw new IllegalStateException("SpringClassRule requires JUnit 4.12 or higher.");
-		}
+		Assert.state(ClassUtils.isPresent("org.junit.internal.Throwables", SpringClassRule.class.getClassLoader()),
+				"SpringClassRule requires JUnit 4.12 or higher.");
 	}
 
 
@@ -183,28 +182,26 @@ public class SpringClassRule implements TestRule {
 	 * annotated with {@code @Rule}.
 	 */
 	private static void validateSpringMethodRuleConfiguration(Class<?> testClass) {
-		Field ruleField = null;
-
-		for (Field field : testClass.getFields()) {
-			int modifiers = field.getModifiers();
-			if (!Modifier.isStatic(modifiers) && Modifier.isPublic(modifiers) &&
-					SpringMethodRule.class.isAssignableFrom(field.getType())) {
-				ruleField = field;
-				break;
-			}
-		}
+		Field ruleField = findSpringMethodRuleField(testClass);
 
-		if (ruleField == null) {
-			throw new IllegalStateException(String.format(
+		Assert.state(ruleField != null, () -> String.format(
 					"Failed to find 'public SpringMethodRule' field in test class [%s]. " +
 					"Consult the javadoc for SpringClassRule for details.", testClass.getName()));
-		}
 
-		if (!ruleField.isAnnotationPresent(Rule.class)) {
-			throw new IllegalStateException(String.format(
+		Assert.state(ruleField.isAnnotationPresent(Rule.class), () -> String.format(
 					"SpringMethodRule field [%s] must be annotated with JUnit's @Rule annotation. " +
 					"Consult the javadoc for SpringClassRule for details.", ruleField));
+	}
+
+	private static Field findSpringMethodRuleField(Class<?> testClass) {
+		for (Field field : testClass.getFields()) {
+			int modifiers = field.getModifiers();
+			if (!Modifier.isStatic(modifiers) && Modifier.isPublic(modifiers) &&
+					SpringMethodRule.class.isAssignableFrom(field.getType())) {
+				return field;
+			}
 		}
+		return null;
 	}
 
 	/**

spring-test/src/main/java/org/springframework/test/context/junit4/rules/SpringMethodRule.java

@@ -33,6 +33,7 @@ import org.springframework.test.context.junit4.statements.RunBeforeTestMethodCal
 import org.springframework.test.context.junit4.statements.RunPrepareTestInstanceCallbacks;
 import org.springframework.test.context.junit4.statements.SpringFailOnTimeout;
 import org.springframework.test.context.junit4.statements.SpringRepeat;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ReflectionUtils;
 
@@ -101,9 +102,8 @@ public class SpringMethodRule implements MethodRule {
 	private static final Log logger = LogFactory.getLog(SpringMethodRule.class);
 
 	static {
-		if (!ClassUtils.isPresent("org.junit.internal.Throwables", SpringMethodRule.class.getClassLoader())) {
-			throw new IllegalStateException("SpringMethodRule requires JUnit 4.12 or higher.");
-		}
+		Assert.state(ClassUtils.isPresent("org.junit.internal.Throwables", SpringMethodRule.class.getClassLoader()),
+				"SpringMethodRule requires JUnit 4.12 or higher.");
 	}
 
 
@@ -220,28 +220,26 @@ public class SpringMethodRule implements MethodRule {
 	 * that is annotated with {@code @ClassRule}.
 	 */
 	private static SpringClassRule validateSpringClassRuleConfiguration(Class<?> testClass) {
-		Field ruleField = null;
+		Field ruleField = findSpringClassRuleField(testClass);
+
+		Assert.state(ruleField != null, () -> String.format(
+				"Failed to find 'public static final SpringClassRule' field in test class [%s]. " +
+				"Consult the javadoc for SpringClassRule for details.", testClass.getName()));
+
+		Assert.state(ruleField.isAnnotationPresent(ClassRule.class), () -> String.format(
+				"SpringClassRule field [%s] must be annotated with JUnit's @ClassRule annotation. " +
+				"Consult the javadoc for SpringClassRule for details.", ruleField));
+
+		return (SpringClassRule) ReflectionUtils.getField(ruleField, null);
+	}
 
+	private static Field findSpringClassRuleField(Class<?> testClass) {
 		for (Field field : testClass.getFields()) {
 			if (ReflectionUtils.isPublicStaticFinal(field) && SpringClassRule.class.isAssignableFrom(field.getType())) {
-				ruleField = field;
-				break;
+				return field;
 			}
 		}
-
-		if (ruleField == null) {
-			throw new IllegalStateException(String.format(
-					"Failed to find 'public static final SpringClassRule' field in test class [%s]. " +
-					"Consult the javadoc for SpringClassRule for details.", testClass.getName()));
-		}
-
-		if (!ruleField.isAnnotationPresent(ClassRule.class)) {
-			throw new IllegalStateException(String.format(
-					"SpringClassRule field [%s] must be annotated with JUnit's @ClassRule annotation. " +
-					"Consult the javadoc for SpringClassRule for details.", ruleField));
-		}
-
-		return (SpringClassRule) ReflectionUtils.getField(ruleField, null);
+		return null;
 	}
 
 }

spring-test/src/main/java/org/springframework/test/context/support/AbstractDelegatingSmartContextLoader.java

@@ -178,11 +178,9 @@ public abstract class AbstractDelegatingSmartContextLoader implements SmartConte
 				}
 			}
 
-			if (configAttributes.hasClasses()) {
-				throw new IllegalStateException(String.format(
+			Assert.state(!configAttributes.hasClasses(), () -> String.format(
 					"%s should NOT have detected default configuration classes for context configuration %s.",
 					name(getXmlLoader()), configAttributes));
-			}
 
 			// Now let the annotation config loader process the configuration.
 			delegateProcessing(getAnnotationConfigLoader(), configAttributes);
@@ -195,11 +193,9 @@ public abstract class AbstractDelegatingSmartContextLoader implements SmartConte
 				}
 			}
 
-			if (!xmlLoaderDetectedDefaults && configAttributes.hasLocations()) {
-				throw new IllegalStateException(String.format(
+			Assert.state(xmlLoaderDetectedDefaults || !configAttributes.hasLocations(), () -> String.format(
 					"%s should NOT have detected default locations for context configuration %s.",
 					name(getAnnotationConfigLoader()), configAttributes));
-			}
 
 			if (configAttributes.hasLocations() && configAttributes.hasClasses()) {
 				String message = String.format(
@@ -237,12 +233,10 @@ public abstract class AbstractDelegatingSmartContextLoader implements SmartConte
 		Assert.notNull(mergedConfig, "mergedConfig must not be null");
 		List<SmartContextLoader> candidates = Arrays.asList(getXmlLoader(), getAnnotationConfigLoader());
 
-		if (mergedConfig.hasLocations() && mergedConfig.hasClasses()) {
-			throw new IllegalStateException(String.format(
+		Assert.state(!(mergedConfig.hasLocations() && mergedConfig.hasClasses()), () -> String.format(
 				"Neither %s nor %s supports loading an ApplicationContext from %s: "
 						+ "declare either 'locations' or 'classes' but not both.", name(getXmlLoader()),
 				name(getAnnotationConfigLoader()), mergedConfig));
-		}
 
 		for (SmartContextLoader loader : candidates) {
 			// Determine if each loader can load a context from the mergedConfig. If it

spring-test/src/main/java/org/springframework/test/context/support/AbstractTestContextBootstrapper.java

@@ -387,13 +387,11 @@ public abstract class AbstractTestContextBootstrapper implements TestContextBoot
 		Set<ContextCustomizer> contextCustomizers = getContextCustomizers(testClass,
 				Collections.unmodifiableList(configAttributesList));
 
-		if (requireLocationsClassesOrInitializers &&
-				areAllEmpty(locations, classes, initializers, contextCustomizers)) {
-			throw new IllegalStateException(String.format(
-					"%s was unable to detect defaults, and no ApplicationContextInitializers " +
-					"or ContextCustomizers were declared for context configuration attributes %s",
-					contextLoader.getClass().getSimpleName(), configAttributesList));
-		}
+		Assert.state(!(requireLocationsClassesOrInitializers &&
+				areAllEmpty(locations, classes, initializers, contextCustomizers)), () -> String.format(
+				"%s was unable to detect defaults, and no ApplicationContextInitializers " +
+				"or ContextCustomizers were declared for context configuration attributes %s",
+				contextLoader.getClass().getSimpleName(), configAttributesList));
 
 		MergedTestPropertySources mergedTestPropertySources =
 				TestPropertySourceUtils.buildMergedTestPropertySources(testClass);
@@ -463,9 +461,7 @@ public abstract class AbstractTestContextBootstrapper implements TestContextBoot
 		Class<? extends ContextLoader> contextLoaderClass = resolveExplicitContextLoaderClass(configAttributesList);
 		if (contextLoaderClass == null) {
 			contextLoaderClass = getDefaultContextLoaderClass(testClass);
-			if (contextLoaderClass == null) {
-				throw new IllegalStateException("getDefaultContextLoaderClass() must not return null");
-			}
+			Assert.state(contextLoaderClass != null, "getDefaultContextLoaderClass() must not return null");
 		}
 		if (logger.isTraceEnabled()) {
 			logger.trace(String.format("Using ContextLoader class [%s] for test class [%s]",

spring-test/src/main/java/org/springframework/test/context/support/ContextLoaderUtils.java

@@ -101,11 +101,9 @@ abstract class ContextLoaderUtils {
 
 		UntypedAnnotationDescriptor desc =
 				findAnnotationDescriptorForTypes(testClass, contextConfigType, contextHierarchyType);
-		if (desc == null) {
-			throw new IllegalArgumentException(String.format(
+		Assert.notNull(desc, () -> String.format(
 					"Could not find an 'annotation declaring class' for annotation type [%s] or [%s] and test class [%s]",
 					contextConfigType.getName(), contextHierarchyType.getName(), testClass.getName()));
-		}
 
 		while (desc != null) {
 			Class<?> rootDeclaringClass = desc.getRootDeclaringClass();
@@ -237,11 +235,9 @@ abstract class ContextLoaderUtils {
 		Class<ContextConfiguration> annotationType = ContextConfiguration.class;
 
 		AnnotationDescriptor<ContextConfiguration> descriptor = findAnnotationDescriptor(testClass, annotationType);
-		if (descriptor == null) {
-			throw new IllegalArgumentException(String.format(
+		Assert.notNull(descriptor, () -> String.format(
 					"Could not find an 'annotation declaring class' for annotation type [%s] and class [%s]",
 					annotationType.getName(), testClass.getName()));
-		}
 
 		while (descriptor != null) {
 			convertContextConfigToConfigAttributesAndAddToList(descriptor.synthesizeAnnotation(),

spring-test/src/main/java/org/springframework/test/context/transaction/TestContextTransactionUtils.java

@@ -196,10 +196,8 @@ public abstract class TestContextTransactionUtils {
 				// look up single TransactionManagementConfigurer
 				Map<String, TransactionManagementConfigurer> configurers = BeanFactoryUtils.beansOfTypeIncludingAncestors(
 					lbf, TransactionManagementConfigurer.class);
-				if (configurers.size() > 1) {
-					throw new IllegalStateException(
+				Assert.state(configurers.size() <= 1,
 						"Only one TransactionManagementConfigurer may exist in the ApplicationContext");
-				}
 				if (configurers.size() == 1) {
 					return configurers.values().iterator().next().annotationDrivenTransactionManager();
 				}

spring-test/src/main/java/org/springframework/test/context/transaction/TestTransaction.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -18,6 +18,7 @@ package org.springframework.test.context.transaction;
 
 import org.springframework.test.context.TestExecutionListeners;
 import org.springframework.transaction.TransactionStatus;
+import org.springframework.util.Assert;
 
 /**
  * {@code TestTransaction} provides a collection of static utility methods for
@@ -135,9 +136,7 @@ public class TestTransaction {
 
 	private static TransactionContext requireCurrentTransactionContext() {
 		TransactionContext txContext = TransactionContextHolder.getCurrentTransactionContext();
-		if (txContext == null) {
-			throw new IllegalStateException("TransactionContext is not active");
-		}
+		Assert.state(txContext != null, "TransactionContext is not active");
 		return txContext;
 	}
 

spring-test/src/main/java/org/springframework/test/context/transaction/TransactionContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -24,6 +24,7 @@ import org.springframework.transaction.PlatformTransactionManager;
 import org.springframework.transaction.TransactionDefinition;
 import org.springframework.transaction.TransactionException;
 import org.springframework.transaction.TransactionStatus;
+import org.springframework.util.Assert;
 
 /**
  * Transaction context for a specific {@link TestContext}.
@@ -76,10 +77,8 @@ class TransactionContext {
 	}
 
 	void setFlaggedForRollback(boolean flaggedForRollback) {
-		if (this.transactionStatus == null) {
-			throw new IllegalStateException(String.format(
+		Assert.state(this.transactionStatus != null, () -> String.format(
 				"Failed to set rollback flag for test context %s: transaction does not exist.", this.testContext));
-		}
 		this.flaggedForRollback = flaggedForRollback;
 	}
 
@@ -90,10 +89,8 @@ class TransactionContext {
 	 * @throws TransactionException if starting the transaction fails
 	 */
 	void startTransaction() {
-		if (this.transactionStatus != null) {
-			throw new IllegalStateException(
+		Assert.state(this.transactionStatus == null,
 				"Cannot start a new transaction without ending the existing transaction first.");
-		}
 		this.flaggedForRollback = this.defaultRollback;
 		this.transactionStatus = this.transactionManager.getTransaction(this.transactionDefinition);
 		++this.transactionsStarted;
@@ -115,10 +112,8 @@ class TransactionContext {
 				"Ending transaction for test context %s; transaction status [%s]; rollback [%s]", this.testContext,
 				this.transactionStatus, flaggedForRollback));
 		}
-		if (this.transactionStatus == null) {
-			throw new IllegalStateException(String.format(
+		Assert.state(this.transactionStatus != null, () -> String.format(
 				"Failed to end transaction for test context %s: transaction does not exist.", this.testContext));
-		}
 
 		try {
 			if (flaggedForRollback) {

spring-test/src/main/java/org/springframework/test/context/transaction/TransactionalTestExecutionListener.java

@@ -161,9 +161,7 @@ public class TransactionalTestExecutionListener extends AbstractTestExecutionLis
 		Assert.notNull(testMethod, "The test method of the supplied TestContext must not be null");
 
 		TransactionContext txContext = TransactionContextHolder.removeCurrentTransactionContext();
-		if (txContext != null) {
-			throw new IllegalStateException("Cannot start a new transaction without ending the existing transaction.");
-		}
+		Assert.state(txContext == null, "Cannot start a new transaction without ending the existing transaction.");
 
 		PlatformTransactionManager tm = null;
 		TransactionAttribute transactionAttribute = this.attributeSource.getTransactionAttribute(testMethod, testClass);
@@ -183,11 +181,9 @@ public class TransactionalTestExecutionListener extends AbstractTestExecutionLis
 
 			tm = getTransactionManager(testContext, transactionAttribute.getQualifier());
 
-			if (tm == null) {
-				throw new IllegalStateException(String.format(
-						"Failed to retrieve PlatformTransactionManager for @Transactional test for test context %s.",
-						testContext));
-			}
+			Assert.state(tm != null, () -> String.format(
+					"Failed to retrieve PlatformTransactionManager for @Transactional test for test context %s.",
+					testContext));
 		}
 
 		if (tm != null) {

spring-test/src/main/java/org/springframework/test/context/web/AbstractGenericWebContextLoader.java

@@ -104,12 +104,10 @@ public abstract class AbstractGenericWebContextLoader extends AbstractContextLoa
 	 */
 	@Override
 	public final ConfigurableApplicationContext loadContext(MergedContextConfiguration mergedConfig) throws Exception {
-
-		if (!(mergedConfig instanceof WebMergedContextConfiguration)) {
-			throw new IllegalArgumentException(String.format(
+		Assert.isTrue(mergedConfig instanceof WebMergedContextConfiguration, () -> String.format(
 				"Cannot load WebApplicationContext from non-web merged context configuration %s. "
 						+ "Consider annotating your test class with @WebAppConfiguration.", mergedConfig));
-		}
+
 		WebMergedContextConfiguration webMergedConfig = (WebMergedContextConfiguration) mergedConfig;
 
 		if (logger.isDebugEnabled()) {

spring-test/src/main/java/org/springframework/test/context/web/ServletTestExecutionListener.java

@@ -33,6 +33,7 @@ import org.springframework.test.context.TestContext;
 import org.springframework.test.context.TestExecutionListener;
 import org.springframework.test.context.support.AbstractTestExecutionListener;
 import org.springframework.test.context.support.DependencyInjectionTestExecutionListener;
+import org.springframework.util.Assert;
 import org.springframework.web.context.WebApplicationContext;
 import org.springframework.web.context.request.RequestAttributes;
 import org.springframework.web.context.request.RequestContextHolder;
@@ -191,11 +192,9 @@ public class ServletTestExecutionListener extends AbstractTestExecutionListener
 		if (context instanceof WebApplicationContext) {
 			WebApplicationContext wac = (WebApplicationContext) context;
 			ServletContext servletContext = wac.getServletContext();
-			if (!(servletContext instanceof MockServletContext)) {
-				throw new IllegalStateException(String.format(
+			Assert.state(servletContext instanceof MockServletContext, () -> String.format(
 						"The WebApplicationContext for test context %s must be configured with a MockServletContext.",
 						testContext));
-			}
 
 			if (logger.isDebugEnabled()) {
 				logger.debug(String.format(

spring-test/src/main/java/org/springframework/test/web/client/DefaultRequestExpectation.java

@@ -88,9 +88,7 @@ public class DefaultRequestExpectation implements RequestExpectation {
 	@Override
 	public ClientHttpResponse createResponse(ClientHttpRequest request) throws IOException {
 		ResponseCreator responseCreator = getResponseCreator();
-		if (responseCreator == null) {
-			throw new IllegalStateException("createResponse called before ResponseCreator was set");
-		}
+		Assert.state(responseCreator != null, "createResponse() called before ResponseCreator was set");
 		getRequestCount().incrementAndValidate();
 		return responseCreator.createResponse(request);
 	}

spring-test/src/main/java/org/springframework/test/web/servlet/htmlunit/HtmlUnitRequestBuilder.java

@@ -196,7 +196,8 @@ final class HtmlUnitRequestBuilder implements RequestBuilder, Mergeable {
 	 * {@link HttpServletRequest#getContextPath()} which states it can be
 	 * an empty string, or it must start with a "/" and not end with a "/".
 	 * @param contextPath a valid contextPath
-	 * @throws IllegalArgumentException if the contextPath is not a valid {@link HttpServletRequest#getContextPath()}
+	 * @throws IllegalArgumentException if the contextPath is not a valid
+	 * {@link HttpServletRequest#getContextPath()}
 	 */
 	public void setContextPath(String contextPath) {
 		MockMvcWebConnection.validateContextPath(contextPath);
@@ -244,10 +245,8 @@ final class HtmlUnitRequestBuilder implements RequestBuilder, Mergeable {
 			}
 		}
 		else {
-			if (!uriComponents.getPath().startsWith(this.contextPath)) {
-				throw new IllegalArgumentException(uriComponents.getPath() + " should start with contextPath " +
-						this.contextPath);
-			}
+			Assert.isTrue(uriComponents.getPath().startsWith(this.contextPath),
+					() -> uriComponents.getPath() + " should start with contextPath " + this.contextPath);
 			request.setContextPath(this.contextPath);
 		}
 	}
@@ -260,10 +259,8 @@ final class HtmlUnitRequestBuilder implements RequestBuilder, Mergeable {
 			StringTokenizer tokens = new StringTokenizer(cookieHeaderValue, "=;");
 			while (tokens.hasMoreTokens()) {
 				String cookieName = tokens.nextToken().trim();
-				if (!tokens.hasMoreTokens()) {
-					throw new IllegalArgumentException("Expected value for cookie name '" + cookieName
-							+ "'. Full cookie was " + cookieHeaderValue);
-				}
+				Assert.isTrue(tokens.hasMoreTokens(),
+						() -> "Expected value for cookie name '" + cookieName + "'. Full cookie was " + cookieHeaderValue);
 				String cookieValue = tokens.nextToken().trim();
 				processCookie(request, cookies, new Cookie(cookieName, cookieValue));
 			}
@@ -382,9 +379,7 @@ final class HtmlUnitRequestBuilder implements RequestBuilder, Mergeable {
 
 	private Locale parseLocale(String locale) {
 		Matcher matcher = LOCALE_PATTERN.matcher(locale);
-		if (!matcher.matches()) {
-			throw new IllegalArgumentException("Invalid locale " + locale);
-		}
+		Assert.isTrue(matcher.matches(), () -> "Invalid locale " + locale);
 		String language = matcher.group(1);
 		String country = matcher.group(2);
 		if (country == null) {

spring-test/src/main/java/org/springframework/test/web/servlet/htmlunit/MockMvcWebConnection.java

@@ -111,12 +111,8 @@ public final class MockMvcWebConnection implements WebConnection {
 		if (contextPath == null || "".equals(contextPath)) {
 			return;
 		}
-		if (!contextPath.startsWith("/")) {
-			throw new IllegalArgumentException("contextPath '" + contextPath + "' must start with '/'.");
-		}
-		if (contextPath.endsWith("/")) {
-			throw new IllegalArgumentException("contextPath '" + contextPath + "' must not end with '/'.");
-		}
+		Assert.isTrue(contextPath.startsWith("/"), () -> "contextPath '" + contextPath + "' must start with '/'.");
+		Assert.isTrue(!contextPath.endsWith("/"), () -> "contextPath '" + contextPath + "' must not end with '/'.");
 	}
 
 

spring-test/src/main/java/org/springframework/test/web/servlet/request/MockHttpServletRequestBuilder.java

@@ -751,10 +751,8 @@ public class MockHttpServletRequestBuilder
 	public MockHttpServletRequest postProcessRequest(MockHttpServletRequest request) {
 		for (RequestPostProcessor postProcessor : this.postProcessors) {
 			request = postProcessor.postProcessRequest(request);
-			if (request == null) {
-				throw new IllegalStateException(
-						"Post-processor [" + postProcessor.getClass().getName() + "] returned null");
-			}
+			Assert.state(request != null,
+					() -> "Post-processor [" + postProcessor.getClass().getName() + "] returned null");
 		}
 		return request;
 	}