feat(#314): first naive implementation of RuleInherianceInTests

docs/rules/inheritance-in-tests.md

@@ -0,0 +1,6 @@
+# Inheritance in tests
+
+@todo #314:90min Add documentation for the RuleInheritenceInTests.java.
+The documentation should be added to the `docs/rules/inheritance-in-tests.md` file.
+The documentation should contain the description of the rule and the
+examples of the correct and incorrect code.

src/it/all-incorrect/verify.groovy

@@ -38,6 +38,6 @@ String log = new File(basedir, 'build.log').text;
   "Test name 'testAnother' doesn't follow naming rules, because test name doesn't have to contain the word 'test'",
   "Test name 'testAnother' doesn't follow naming rules, because the test name has to be written using present tense",
   "Method 'containsLineHitter' contains line hitter anti-pattern",
-  "The class 'UsesInheritenceTest' uses inheritance in tests, which is dangerous",
+  "The test class 'UsesInheritenceTest' uses inheritance, which is dangerous for maintainability",
 ].each { assert log.contains(it): "Log doesn't contain ['$it']" }
 true

src/main/java/com/github/lombrozo/testnames/TestClass.java

@@ -146,7 +146,7 @@ public Fake(final String name, final TestCase... all) {
          * @param suppressed Suppressed rules
          */
         public Fake(final List<String> suppressed) {
-            this("FakeClassTest", Collections.emptyList(), suppressed);
+            this(Fake.DEFAULT_NAME, Collections.emptyList(), suppressed);
         }
 
         /**
@@ -155,7 +155,7 @@ public Fake(final List<String> suppressed) {
          * @param all All cases
          */
         public Fake(final List<String> suppressed, final TestCase... all) {
-            this("FakeClassTest", Arrays.asList(all), suppressed);
+            this(Fake.DEFAULT_NAME, Arrays.asList(all), suppressed);
         }
 
         /**
@@ -185,6 +185,19 @@ public Fake(final TestClassCharacteristics props) {
             this(name, all, suppressed, new TestClassCharacteristics.Fake(false));
         }
 
+        /**
+         * Constructor.
+         * @param parent The parent class name
+         */
+        Fake(final String parent) {
+            this(
+                Fake.DEFAULT_NAME,
+                Collections.emptyList(),
+                Collections.emptyList(),
+                new TestClassCharacteristics.Fake(parent)
+            );
+        }
+
         /**
          * Main ctor.
          * @param name The name of test class

src/main/java/com/github/lombrozo/testnames/TestClassCharacteristics.java

@@ -57,6 +57,12 @@ public interface TestClassCharacteristics {
      */
     int numberOfMethods();
 
+    /**
+     * The parent class name.
+     * @return The parent class name.
+     */
+    String parent();
+
     /**
      * Fake implementation for test characteristics.
      *
@@ -66,6 +72,11 @@ public interface TestClassCharacteristics {
     @ToString
     final class Fake implements TestClassCharacteristics {
 
+        /**
+         * The default parent class name.
+         */
+        private static final String DEFAULT_PARENT = "java.lang.Object";
+
         /**
          * Is the test class a JUnit extension?
          */
@@ -86,12 +97,25 @@ final class Fake implements TestClassCharacteristics {
          */
         private final boolean integration;
 
+        /**
+         * The parent class name.
+         */
+        private final String parent;
+
         /**
          * Constructor.
          * @param extension Is the test class a JUnit extension?
          */
         public Fake(final boolean extension) {
-            this(extension, 0, 0, false);
+            this(extension, 0, 0, false, Fake.DEFAULT_PARENT);
+        }
+
+        /**
+         * Constructor.
+         * @param parent The parent class name.
+         */
+        public Fake(final String parent) {
+            this(false, 0, 0, false, parent);
         }
 
         /**
@@ -100,7 +124,7 @@ public Fake(final boolean extension) {
          * @param nmethods The total number of methods in the class.
          */
         public Fake(final int ntests, final int nmethods) {
-            this(false, ntests, nmethods, false);
+            this(false, ntests, nmethods, false, Fake.DEFAULT_PARENT);
         }
 
         /**
@@ -115,12 +139,14 @@ public Fake(
             final boolean extension,
             final int ntests,
             final int nmethods,
-            final boolean integration
+            final boolean integration,
+            final String parent
         ) {
             this.junit = extension;
             this.tests = ntests;
             this.methods = nmethods;
             this.integration = integration;
+            this.parent = parent;
         }
 
         @Override
@@ -142,6 +168,11 @@ public int numberOfTests() {
         public int numberOfMethods() {
             return this.methods;
         }
+
+        @Override
+        public String parent() {
+            return this.parent;
+        }
     }
 
     /**
@@ -172,5 +203,10 @@ public int numberOfTests() {
         public int numberOfMethods() {
             return 0;
         }
+
+        @Override
+        public String parent() {
+            return Fake.DEFAULT_PARENT;
+        }
     }
 }

src/main/java/com/github/lombrozo/testnames/bytecode/BytecodeTestClassCharacteristics.java

@@ -93,6 +93,21 @@ public int numberOfMethods() {
         return this.klass.getDeclaredMethods().length;
     }
 
+    @Override
+    public String parent() {
+        try {
+            return this.klass.getSuperclass().getName();
+        } catch (final NotFoundException exception) {
+            throw new IllegalStateException(
+                String.format(
+                    "Can't get parent of class %s",
+                    this.klass.getName()
+                ),
+                exception
+            );
+        }
+    }
+
     /**
      * Checks whether a method is test-method.
      * @param method To check.

src/main/java/com/github/lombrozo/testnames/javaparser/JavaParserCharacteristics.java

@@ -69,4 +69,19 @@ public int numberOfTests() {
     public int numberOfMethods() {
         return (int) this.klass.methods().count();
     }
+
+    @Override
+    public String parent() {
+        return this.klass.parents()
+            .stream()
+            .findFirst()
+            .orElseThrow(
+                () -> new IllegalStateException(
+                    String.format(
+                        "Can't get parent of class %s",
+                        this.klass
+                    )
+                )
+            ).getName();
+    }
 }

src/main/java/com/github/lombrozo/testnames/rules/RuleInheritenceInTests.java

@@ -0,0 +1,75 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2022-2023 Volodya
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.github.lombrozo.testnames.rules;
+
+import com.github.lombrozo.testnames.Complaint;
+import com.github.lombrozo.testnames.Rule;
+import com.github.lombrozo.testnames.TestClass;
+import com.github.lombrozo.testnames.complaints.ComplaintLinked;
+import java.util.Collection;
+import java.util.Collections;
+
+/**
+ * The rule that checks a test class doesn't use inheritance.
+ * @since 1.2.0
+ */
+public final class RuleInheritenceInTests implements Rule {
+
+    /**
+     * Test class.
+     */
+    private final TestClass clazz;
+
+    /**
+     * Constructor.
+     * @param clazz Test class.
+     */
+    public RuleInheritenceInTests(final TestClass clazz) {
+        this.clazz = clazz;
+    }
+
+    @Override
+    public Collection<Complaint> complaints() {
+        final String parent = this.clazz.characteristics().parent();
+        if (parent.equals("java.lang.Object")) {
+            return Collections.emptyList();
+        } else {
+            return Collections.singleton(
+                new ComplaintLinked(
+                    String.format(
+                        "The test class '%s' has parent class '%s', inheritance in tests is dangerous for maintainability",
+                        this.clazz.name(),
+                        parent
+                    ),
+                    String.format(
+                        "Please rename remove all the parents classes from the %s test class",
+                        this.clazz.name()
+                    ),
+                    this.getClass(),
+                    "inheritance-in-tests.md"
+                )
+            );
+        }
+    }
+}

src/test/java/com/github/lombrozo/testnames/rules/RuleInheritenceInTestsTest.java

@@ -0,0 +1,36 @@
+package com.github.lombrozo.testnames.rules;
+
+import com.github.lombrozo.testnames.TestClass;
+import com.github.lombrozo.testnames.TestClassCharacteristics;
+import org.hamcrest.MatcherAssert;
+import org.hamcrest.Matchers;
+import org.junit.jupiter.api.Test;
+
+class RuleInheritenceInTestsTest {
+
+    @Test
+    void doesNotFoundParents() {
+        MatcherAssert.assertThat(
+            "Should not find any complaints if there are no parents",
+            new RuleInheritenceInTests(new TestClass.Fake()).complaints(),
+            Matchers.emptyIterable()
+        );
+    }
+
+    @Test
+    void hasSomeParent() {
+        final String parent = "some.parent.Parent";
+        final TestClass.Fake clazz = new TestClass.Fake(new TestClassCharacteristics.Fake(parent));
+        MatcherAssert.assertThat(
+            "Should find complaint if there is a parent",
+            new RuleInheritenceInTests(clazz).complaints().iterator().next().message(),
+            Matchers.containsString(
+                String.format(
+                    "The test class '%s' has parent class '%s', inheritance in tests is dangerous for maintainability",
+                    clazz.name(),
+                    parent
+                )
+            )
+        );
+    }
+}