AssertJ has a more idiomatic way of asserting that a boolean is true.…

… This recipe will find instances of:

 -`assertThat(boolean).isEqualTo(true)` and replace them with `isTrue()`.
 -`assertThat(boolean).isEqualTo(false)` and replace them with `isFalse()`.

Signed-off-by: Marvin Froeder <velo.br@gmail.com>

src/main/java/org/openrewrite/java/testing/assertj/IsEqualToBoolean.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2024 the original author or authors.
+ * <p>
+ * 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
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.openrewrite.java.testing.assertj;
+
+import org.openrewrite.ExecutionContext;
+import org.openrewrite.Preconditions;
+import org.openrewrite.Recipe;
+import org.openrewrite.TreeVisitor;
+import org.openrewrite.java.JavaIsoVisitor;
+import org.openrewrite.java.MethodMatcher;
+import org.openrewrite.java.search.UsesMethod;
+import org.openrewrite.java.tree.J;
+import org.openrewrite.java.tree.J.MethodInvocation;
+import org.openrewrite.java.tree.JavaType.Method;
+
+import java.util.Collections;
+
+/**
+ * AssertJ has a more idiomatic way of asserting that a boolean is true. This
+ * recipe will find instances of:
+ * 
+ * -`assertThat(boolean).isEqualTo(true)` and replace them with `isTrue()`.
+ * -`assertThat(boolean).isEqualTo(false)` and replace them with `isFalse()`.
+ */
+public class IsEqualToBoolean extends Recipe {
+
+    private static final MethodMatcher IS_EQUAL_TO = new MethodMatcher(
+            "org.assertj.core.api.AbstractBooleanAssert isEqualTo(boolean)");
+
+    @Override
+    public String getDisplayName() {
+        return "Convert `assertThat(String).isEqualTo(true)` to `isTrue()` and `isEqualTo(false)` to `isFalse()`";
+    }
+
+    @Override
+    public String getDescription() {
+        return "Adopt idiomatic AssertJ assertion for true booleans.";
+    }
+
+    @Override
+    public TreeVisitor<?, ExecutionContext> getVisitor() {
+        return Preconditions.check(new UsesMethod<>(IS_EQUAL_TO), new JavaIsoVisitor<ExecutionContext>() {
+            @Override
+            public J.MethodInvocation visitMethodInvocation(J.MethodInvocation method, ExecutionContext ctx) {
+                MethodInvocation mi = super.visitMethodInvocation(method, ctx);
+                if (IS_EQUAL_TO.matches(mi)) {
+                    String methodName;
+                    if (J.Literal.isLiteralValue(mi.getArguments().get(0), true)) {
+                        methodName = "isTrue";
+                    } else {
+                        methodName = "isFalse";
+                    }
+                    Method isBooleanMethod = mi.getMethodType().withName(methodName);
+                    return mi.withName(mi.getName().withSimpleName(methodName).withType(isBooleanMethod))
+                            .withMethodType(isBooleanMethod).withArguments(Collections.emptyList());
+                }
+                return mi;
+            }
+        });
+    }
+}

src/test/java/org/openrewrite/java/testing/assertj/IsEqualToBooleanTest.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2024 the original author or authors.
+ * <p>
+ * 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
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.openrewrite.java.testing.assertj;
+
+import static org.openrewrite.java.Assertions.java;
+
+import org.junit.jupiter.api.Test;
+import org.openrewrite.InMemoryExecutionContext;
+import org.openrewrite.java.JavaParser;
+import org.openrewrite.test.RecipeSpec;
+import org.openrewrite.test.RewriteTest;
+
+class IsEqualToBooleanTest implements RewriteTest {
+
+    @Override
+    public void defaults(RecipeSpec spec) {
+        spec
+        .parser(JavaParser.fromJavaVersion().classpathFromResources(new InMemoryExecutionContext(), "assertj-core-3.24"))
+                .recipe(new IsEqualToBoolean());
+    }
+
+    @Test
+    void convertsIsEqualToTrue() {
+        rewriteRun(
+                // language=java
+                java("""
+                        import static org.assertj.core.api.Assertions.assertThat;
+                        class Test {
+                            void test() {
+                                assertThat(true).isEqualTo(true);
+                            }
+                        }
+                        """, """
+                        import static org.assertj.core.api.Assertions.assertThat;
+                        class Test {
+                            void test() {
+                                assertThat(true).isTrue();
+                            }
+                        }
+                        """));
+    }
+
+    @Test
+    void convertsIsEqualToFalse() {
+        rewriteRun(
+                // language=java
+                java("""
+                        import static org.assertj.core.api.Assertions.assertThat;
+                        class Test {
+                            void test() {
+                                assertThat(false).isEqualTo(false);
+                            }
+                        }
+                        """, """
+                        import static org.assertj.core.api.Assertions.assertThat;
+                        class Test {
+                            void test() {
+                                assertThat(false).isFalse();
+                            }
+                        }
+                        """));
+    }
+
+}