feat(spoon): Add EqualsHashcode badsmell (#899)

code-transformation/src/main/java/xyz/keksdose/spoon/code_solver/analyzer/spoon/AnalyzerResultVisitor.java

@@ -11,6 +11,7 @@
 import io.github.martinwitt.spoon_analyzer.badsmells.access_static_via_instance.AccessStaticViaInstance;
 import io.github.martinwitt.spoon_analyzer.badsmells.array_can_be_replaced_with_enum_values.ArrayCanBeReplacedWithEnumValues;
 import io.github.martinwitt.spoon_analyzer.badsmells.charset_object_can_be_used.CharsetObjectCanBeUsed;
+import io.github.martinwitt.spoon_analyzer.badsmells.equals_hashcode.EqualsHashcode;
 import io.github.martinwitt.spoon_analyzer.badsmells.final_static_method.FinalStaticMethod;
 import io.github.martinwitt.spoon_analyzer.badsmells.innerclass_may_be_static.InnerClassMayBeStatic;
 import io.github.martinwitt.spoon_analyzer.badsmells.non_protected_constructor_In_abstract_class.NonProtectedConstructorInAbstractClass;
@@ -182,6 +183,14 @@ public AnalyzerResult visit(FinalStaticMethod badSmell) {
         return toSpoonAnalyzerResult(badSmell, badSmell.getMethod().getPosition(), snippet);
     }
 
+    @Override
+    public AnalyzerResult visit(EqualsHashcode badSmell) {
+        CtType<?> clone = badSmell.getAffectedType().clone();
+        clone.setTypeMembers(new ArrayList<>());
+        String snippet = clone.toString();
+        return toSpoonAnalyzerResult(badSmell, badSmell.getAffectedType().getPosition(), snippet);
+    }
+
     private Optional<String> trygetOriginalSourceCode(CtElement element) {
         try {
             File file = element.getPosition().getCompilationUnit().getFile();

spoon-analyzer/src/main/java/io/github/martinwitt/spoon_analyzer/BadSmellVisitor.java

@@ -4,6 +4,7 @@
 import io.github.martinwitt.spoon_analyzer.badsmells.access_static_via_instance.AccessStaticViaInstance;
 import io.github.martinwitt.spoon_analyzer.badsmells.array_can_be_replaced_with_enum_values.ArrayCanBeReplacedWithEnumValues;
 import io.github.martinwitt.spoon_analyzer.badsmells.charset_object_can_be_used.CharsetObjectCanBeUsed;
+import io.github.martinwitt.spoon_analyzer.badsmells.equals_hashcode.EqualsHashcode;
 import io.github.martinwitt.spoon_analyzer.badsmells.final_static_method.FinalStaticMethod;
 import io.github.martinwitt.spoon_analyzer.badsmells.innerclass_may_be_static.InnerClassMayBeStatic;
 import io.github.martinwitt.spoon_analyzer.badsmells.non_protected_constructor_In_abstract_class.NonProtectedConstructorInAbstractClass;
@@ -63,6 +64,10 @@ default U visit(FinalStaticMethod badSmell) {
         return emptyResult();
     }
 
+    default U visit(EqualsHashcode badSmell) {
+        return emptyResult();
+    }
+
     default U emptyResult() {
         return null;
     }

spoon-analyzer/src/main/java/io/github/martinwitt/spoon_analyzer/badsmells/equals_hashcode/EqualsHashcode.java

@@ -0,0 +1,39 @@
+package io.github.martinwitt.spoon_analyzer.badsmells.equals_hashcode;
+
+import io.github.martinwitt.spoon_analyzer.BadSmell;
+import io.github.martinwitt.spoon_analyzer.BadSmellVisitor;
+import spoon.reflect.declaration.CtType;
+
+/**
+ * This badsmell means the class does not override equals() and hashcode() methods together.
+ * Overriding only one of them is not enough and can lead to unexpected behavior.
+ */
+public class EqualsHashcode implements BadSmell {
+
+    private CtType<?> affectedType;
+
+    public EqualsHashcode(CtType<?> affectedType) {
+        this.affectedType = affectedType;
+    }
+
+    @Override
+    public String getName() {
+        return "EqualsHashcode";
+    }
+
+    @Override
+    public String getDescription() {
+        return "This class does not override equals() and hashcode() methods together.";
+    }
+
+    @Override
+    public CtType<?> getAffectedType() {
+        return affectedType;
+    }
+
+    @Override
+    public <T> T accept(BadSmellVisitor<T> visitor) {
+        // TODO Auto-generated method stub
+        throw new UnsupportedOperationException("Unimplemented method 'accept'");
+    }
+}

spoon-analyzer/src/main/java/io/github/martinwitt/spoon_analyzer/badsmells/equals_hashcode/EqualsHashcodeAnalyzer.java

@@ -0,0 +1,38 @@
+package io.github.martinwitt.spoon_analyzer.badsmells.equals_hashcode;
+
+import io.github.martinwitt.spoon_analyzer.BadSmell;
+import io.github.martinwitt.spoon_analyzer.LocalAnalyzer;
+import java.util.List;
+import spoon.reflect.declaration.CtMethod;
+import spoon.reflect.declaration.CtType;
+
+public class EqualsHashcodeAnalyzer implements LocalAnalyzer {
+
+    @Override
+    public List<BadSmell> analyze(CtType<?> clazz) {
+
+        boolean hasEquals = false;
+        boolean hasHashcode = false;
+        for (CtMethod<?> methods : clazz.getMethods()) {
+            if (isEqualsMethod(methods)) {
+                hasEquals = true;
+            }
+            if (isHashcodeMethod(methods)) {
+                hasHashcode = true;
+            }
+        }
+        // if only one of them is present, it is a badsmell, otherwise not
+        if ((!hasEquals && hasHashcode) || (hasEquals && !hasHashcode)) {
+            return List.of(new EqualsHashcode(clazz));
+        }
+        return List.of();
+    }
+
+    private boolean isEqualsMethod(CtMethod<?> method) {
+        return method.getSimpleName().equals("equals");
+    }
+
+    private boolean isHashcodeMethod(CtMethod<?> method) {
+        return method.getSimpleName().equals("hashCode");
+    }
+}

spoon-analyzer/src/test/java/io/github/martinwitt/spoon_analyzer/badsmells/equals_hashcode/EqualsHashcodeAnalyzerTest.java

@@ -0,0 +1,51 @@
+package io.github.martinwitt.spoon_analyzer.badsmells.equals_hashcode;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+import spoon.Launcher;
+import spoon.reflect.declaration.CtType;
+import spoon.support.compiler.VirtualFile;
+
+public class EqualsHashcodeAnalyzerTest {
+
+    @Test
+    void noEqualsNoHashcode() {
+        String code = "public class A { }";
+
+        Launcher launcher = new Launcher();
+        launcher.addInputResource(new VirtualFile(code));
+        var model = launcher.buildModel();
+        EqualsHashcodeAnalyzer analyzer = new EqualsHashcodeAnalyzer();
+        CtType<?> simpleClass = model.getAllTypes().stream().findFirst().get();
+        var result = analyzer.analyze(simpleClass);
+        assertEquals(0, result.size());
+    }
+
+    @Test
+    void UpperClassEqualsNoHashcode() {
+        String code =
+                """
+            class A {
+
+            @Override
+            public boolean equals(Object obj) {
+              return super.equals(obj);
+            }
+          }
+
+          class B extends A {
+
+          }
+        """;
+
+        Launcher launcher = new Launcher();
+        launcher.addInputResource(new VirtualFile(code));
+        var model = launcher.buildModel();
+        EqualsHashcodeAnalyzer analyzer = new EqualsHashcodeAnalyzer();
+        CtType<?> simpleClass = model.getAllTypes().stream().findFirst().get();
+        var result = analyzer.analyze(simpleClass);
+
+        assertEquals(1, result.size());
+    }
+}