Revise @DisabledIf support for JUnit Jupiter

- Extracted stand-alone DisabledIfCondition from the SpringExtension
  so that the condition is only evaluated when necessary.

- Simplified implementation of DisabledIfCondition.

- Overhauled and extended logging in DisabledIfCondition.

- DisabledIfCondition now throws an IllegalStateException if @DisabledIf
  is not present on the test element or if the expression does not
  evaluate to a String or Boolean.

- Each generated ConditionEvaluationResult now includes the actual
  expression in the default reason.

- @DisabledIf is now auto-configured to be evaluated by the
  DisabledIfCondition since it is now meta-annotated with
  @ExtendWith(DisabledIfCondition.class)

- Overhauled documentation for @DisabledIf and provided standard
  examples as well as an @DisabledOnMac annotation to demonstrate
  support for custom composed annotations.

Issue: SPR-14614

spring-test/src/test/java/org/springframework/test/context/junit/jupiter/DisabledIfTestCase.java

@@ -18,27 +18,27 @@ package org.springframework.test.context.junit.jupiter;
 
 import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
-import org.junit.jupiter.api.extension.ExtendWith;
+
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.TestPropertySource;
 
-import static org.junit.jupiter.api.Assertions.fail;
+import static org.junit.jupiter.api.Assertions.*;
 
 /**
- * Integration tests which demonstrate usage of {@link DisabledIf @DisabledIf}
- * enabled by {@link SpringExtension} in a JUnit 5 (Jupiter) environment.
+ * Integration tests which verify support for {@link DisabledIf @DisabledIf}
+ * in conjunction with the {@link SpringExtension} in a JUnit 5 (Jupiter)
+ * environment.
  *
  * @author Tadaya Tsuyukubo
+ * @author Sam Brannen
  * @since 5.0
  * @see DisabledIf
  * @see SpringExtension
  */
 class DisabledIfTestCase {
 
-	@ExtendWith(SpringExtension.class)
-	@ContextConfiguration(classes = Config.class)
+	@SpringJUnitConfig(Config.class)
 	@TestPropertySource(properties = "foo = true")
 	@Nested
 	class DisabledIfOnMethodTestCase {
@@ -73,6 +73,18 @@ class DisabledIfTestCase {
 			fail("This test must be disabled");
 		}
 
+		@Test
+		@DisabledIf("#{6 * 7 == 42}")
+		void disabledBySpelMathematicalComparison() {
+			fail("This test must be disabled");
+		}
+
+		@Test
+		@DisabledOnMac
+		void disabledBySpelOsCheckInCustomComposedAnnotation() {
+			assertFalse(System.getProperty("os.name").contains("Mac"), "This test must be disabled on Mac OS");
+		}
+
 		@Test
 		@DisabledIf("#{@booleanTrueBean}")
 		void disabledBySpelBooleanTrueBean() {
@@ -87,8 +99,7 @@ class DisabledIfTestCase {
 
 	}
 
-	@ExtendWith(SpringExtension.class)
-	@ContextConfiguration(classes = Config.class)
+	@SpringJUnitConfig(Config.class)
 	@Nested
 	@DisabledIf("true")
 	class DisabledIfOnClassTestCase {
@@ -98,7 +109,8 @@ class DisabledIfTestCase {
 			fail("This test must be disabled");
 		}
 
-		// Even though method level condition is not disabling test, class level condition should take precedence
+		// Even though method level condition is not disabling test, class level condition
+		// should take precedence
 		@Test
 		@DisabledIf("false")
 		void bar() {
@@ -109,6 +121,7 @@ class DisabledIfTestCase {
 
 	@Configuration
 	static class Config {
+
 		@Bean
 		Boolean booleanTrueBean() {
 			return Boolean.TRUE;

spring-test/src/test/java/org/springframework/test/context/junit/jupiter/DisabledOnMac.java

@@ -0,0 +1,38 @@
+/*
+ * 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.
+ * 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.test.context.junit.jupiter;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Demo <em>composed annotation</em> for {@link DisabledIf @DisabledIf} that
+ * disables a test class or test method if the current operating system is
+ * Mac OS.
+ *
+ * @author Sam Brannen
+ * @since 5.0
+ */
+@Target({ ElementType.TYPE, ElementType.METHOD })
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@DisabledIf(expression = "#{systemProperties['os.name'].toLowerCase().contains('mac')}", reason = "Disabled on Mac OS")
+public @interface DisabledOnMac {
+}