Issue: TNG#475 - Implement ArchRule that checks if test class reside …

…in the same package as implementation class

Signed-off-by: Marcin Słowiak <marcin.slowiak.007@gmail.com>

archunit/src/main/java/com/tngtech/archunit/library/GeneralCodingRules.java

@@ -15,6 +15,11 @@
  */
 package com.tngtech.archunit.library;
 
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.stream.Collectors;
+
 import com.tngtech.archunit.PublicAPI;
 import com.tngtech.archunit.core.domain.AccessTarget.FieldAccessTarget;
 import com.tngtech.archunit.core.domain.JavaAccess.Functions.Get;
@@ -24,6 +29,7 @@
 import com.tngtech.archunit.core.importer.ClassFileImporter;
 import com.tngtech.archunit.lang.ArchCondition;
 import com.tngtech.archunit.lang.ArchRule;
+import com.tngtech.archunit.lang.ConditionEvents;
 
 import static com.tngtech.archunit.PublicAPI.Usage.ACCESS;
 import static com.tngtech.archunit.base.DescribedPredicate.not;
@@ -37,13 +43,15 @@
 import static com.tngtech.archunit.core.domain.properties.HasOwner.Predicates.With.owner;
 import static com.tngtech.archunit.core.domain.properties.HasParameterTypes.Predicates.rawParameterTypes;
 import static com.tngtech.archunit.core.domain.properties.HasType.Functions.GET_RAW_TYPE;
+import static com.tngtech.archunit.lang.SimpleConditionEvent.violated;
 import static com.tngtech.archunit.lang.conditions.ArchConditions.accessField;
 import static com.tngtech.archunit.lang.conditions.ArchConditions.beAnnotatedWith;
 import static com.tngtech.archunit.lang.conditions.ArchConditions.callCodeUnitWhere;
 import static com.tngtech.archunit.lang.conditions.ArchConditions.callMethodWhere;
 import static com.tngtech.archunit.lang.conditions.ArchConditions.dependOnClassesThat;
 import static com.tngtech.archunit.lang.conditions.ArchConditions.setFieldWhere;
 import static com.tngtech.archunit.lang.conditions.ArchPredicates.is;
+import static com.tngtech.archunit.lang.syntax.ArchRuleDefinition.classes;
 import static com.tngtech.archunit.lang.syntax.ArchRuleDefinition.noClasses;
 import static com.tngtech.archunit.lang.syntax.ArchRuleDefinition.noFields;
 
@@ -407,4 +415,54 @@ private static ArchCondition<JavaField> beAnnotatedWithAnInjectionAnnotation() {
                     .as("no classes should use field injection")
                     .because("field injection is considered harmful; use constructor injection or setter injection instead; "
                             + "see https://stackoverflow.com/q/39890849 for detailed explanations");
+
+    /**
+     * A rule that checks that every test class has the same package as implementation class.
+     */
+    @PublicAPI(usage = ACCESS)
+    public static ArchRule testClassesShouldResideInTheSamePackageAsImplementation(String testClassPattern) {
+        return classes().should(new ArchCondition<JavaClass>("have the same package as test classes") {
+            Map<String, String> simpleTestNameToPackage = new HashMap<>();
+
+            @Override
+            public void init(Collection<JavaClass> allClasses) {
+                simpleTestNameToPackage = allClasses.stream()
+                        .filter(clazz -> clazz.getName().endsWith(testClassPattern))
+                        .collect(Collectors.toMap(JavaClass::getSimpleName, JavaClass::getPackageName));
+            }
+
+            @Override
+            public void check(JavaClass implementationClass, ConditionEvents events) {
+                final String implementationClassName = implementationClass.getSimpleName();
+                final String implementationClassPackageName = implementationClass.getPackageName();
+                final String possibleTestClassName = implementationClassName + testClassPattern;
+                final String possibleTestClassPackageName = simpleTestNameToPackage.get(possibleTestClassName);
+
+                final boolean isTestClassInWrongPackage = possibleTestClassPackageName != null
+                        && !possibleTestClassPackageName.equals(implementationClassPackageName);
+
+                if (isTestClassInWrongPackage) {
+                    events.add(
+                            violated(
+                                    implementationClass,
+                                    String.format(
+                                            "Test class %s.%s is in the wrong package. Should be inside %s package",
+                                            possibleTestClassPackageName, possibleTestClassName, implementationClassPackageName
+                                    )
+                            )
+                    );
+                }
+            }
+        });
+    }
+
+    /**
+     * A rule that checks that every test class has the same package as implementation class.
+     */
+    @PublicAPI(usage = ACCESS)
+    public static ArchRule testClassesShouldResideInTheSamePackageAsImplementation() {
+        final String defaultTestClassSuffix = "Test";
+        return testClassesShouldResideInTheSamePackageAsImplementation(defaultTestClassSuffix);
+    }
+
 }

archunit/src/test/java/com/tngtech/archunit/library/TestClassesPackagesAlignedWithImplementationTest.java

@@ -0,0 +1,60 @@
+package com.tngtech.archunit.library;
+
+import com.tngtech.archunit.core.domain.JavaClasses;
+import com.tngtech.archunit.core.importer.ClassFileImporter;
+import com.tngtech.archunit.library.testclasses.packages.correct.SecondClass;
+import com.tngtech.archunit.library.testclasses.packages.incorrect.FirstClass;
+import org.junit.Test;
+
+import static com.tngtech.archunit.library.GeneralCodingRules.testClassesShouldResideInTheSamePackageAsImplementation;
+import static org.assertj.core.api.Assertions.assertThatNoException;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+public class TestClassesPackagesAlignedWithImplementationTest {
+
+    private final JavaClasses correctClasses = new ClassFileImporter().importPackagesOf(SecondClass.class);
+    private final JavaClasses incorrectClasses = new ClassFileImporter().importPackagesOf(FirstClass.class);
+
+    @Test
+    public void should_fail_when_test_class_reside_in_different_package_as_implementation() {
+        // given
+        final String correctPackage = "com.tngtech.archunit.library.testclasses.packages.incorrect";
+        final String incorrectTestClass = "com.tngtech.archunit.library.testclasses.packages.incorrect.dir.FirstClassTest";
+        final String expectedErrorMessage = "Test class " + incorrectTestClass + " is in the wrong package. Should be inside " + correctPackage + " package";
+
+        // when & then
+        assertThatThrownBy(() -> testClassesShouldResideInTheSamePackageAsImplementation().check(incorrectClasses))
+                .isInstanceOf(AssertionError.class)
+                .hasMessageContaining(expectedErrorMessage);
+    }
+
+    @Test
+    public void should_fail_when_test_class_reside_in_different_package_as_implementation_when_have_custom_suffix() {
+        // given
+        final String correctPackage = "com.tngtech.archunit.library.testclasses.packages.incorrect";
+        final String incorrectTestClass = "com.tngtech.archunit.library.testclasses.packages.incorrect.dir.FirstClassTestingScenario";
+        final String expectedErrorMessage = "Test class " + incorrectTestClass + " is in the wrong package. Should be inside " + correctPackage + " package";
+        final String testClassesSuffix = "TestingScenario";
+
+        // when & then
+        assertThatThrownBy(() -> testClassesShouldResideInTheSamePackageAsImplementation(testClassesSuffix).check(incorrectClasses))
+                .isInstanceOf(AssertionError.class)
+                .hasMessageContaining(expectedErrorMessage);
+    }
+
+    @Test
+    public void should_not_fail_when_test_class_and_implementation_class_reside_in_the_same_package() {
+        // when & then
+        assertThatNoException().isThrownBy(() -> testClassesShouldResideInTheSamePackageAsImplementation().check(correctClasses));
+    }
+
+    @Test
+    public void should_not_fail_when_test_class_and_implementation_class_reside_in_the_same_package_with_custom_suffix() {
+        // given
+        final String testClassesSuffix = "TestingScenario";
+
+        // when & then
+        assertThatNoException().isThrownBy(() -> testClassesShouldResideInTheSamePackageAsImplementation(testClassesSuffix).check(correctClasses));
+    }
+
+}

archunit/src/test/java/com/tngtech/archunit/library/testclasses/packages/correct/SecondClass.java

@@ -0,0 +1,4 @@
+package com.tngtech.archunit.library.testclasses.packages.correct;
+
+public class SecondClass {
+}

archunit/src/test/java/com/tngtech/archunit/library/testclasses/packages/correct/SecondClassTest.java

@@ -0,0 +1,4 @@
+package com.tngtech.archunit.library.testclasses.packages.correct;
+
+class SecondClassTest {
+}

archunit/src/test/java/com/tngtech/archunit/library/testclasses/packages/correct/SecondClassTestingScenario.java

@@ -0,0 +1,4 @@
+package com.tngtech.archunit.library.testclasses.packages.correct;
+
+class SecondClassTestingScenario {
+}

archunit/src/test/java/com/tngtech/archunit/library/testclasses/packages/incorrect/FirstClass.java

@@ -0,0 +1,4 @@
+package com.tngtech.archunit.library.testclasses.packages.incorrect;
+
+public class FirstClass {
+}

archunit/src/test/java/com/tngtech/archunit/library/testclasses/packages/incorrect/dir/FirstClassTest.java

@@ -0,0 +1,4 @@
+package com.tngtech.archunit.library.testclasses.packages.incorrect.dir;
+
+class FirstClassTest {
+}

archunit/src/test/java/com/tngtech/archunit/library/testclasses/packages/incorrect/dir/FirstClassTestingScenario.java

@@ -0,0 +1,4 @@
+package com.tngtech.archunit.library.testclasses.packages.incorrect.dir;
+
+class FirstClassTestingScenario {
+}