More best pratices for AssertJ (#548)

* Added ChainedAssertions for Iterator hasNext

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

* Create dedicated test for IsEqualToEmptyString

* 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>

* Apply suggestions from code review

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* Apply formatter

* Add missing `@Test` annotations

---------

Signed-off-by: Marvin Froeder <velo.br@gmail.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Tim te Beek <tim@moderne.io>

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:
+ * <p>
+ * -`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/main/resources/META-INF/rewrite/assertj.yml

@@ -25,6 +25,7 @@ recipeList:
   - org.openrewrite.java.testing.hamcrest.MigrateHamcrestToAssertJ
   - org.openrewrite.java.testing.assertj.JUnitToAssertj
   - org.openrewrite.java.testing.assertj.StaticImports
+  - org.openrewrite.java.testing.assertj.IsEqualToBoolean
   - org.openrewrite.java.testing.assertj.SimplifyChainedAssertJAssertions
   - org.openrewrite.java.testing.assertj.IsEqualToEmptyString
 
@@ -337,6 +338,16 @@ recipeList:
       assertToReplace: isSameAs
       dedicatedAssertion: containsSame
       requiredType: java.util.Optional
+  - org.openrewrite.java.testing.assertj.SimplifyChainedAssertJAssertion:
+      chainedAssertion: hasNext
+      assertToReplace: isTrue
+      dedicatedAssertion: hasNext
+      requiredType: java.util.Iterator
+  - org.openrewrite.java.testing.assertj.SimplifyChainedAssertJAssertion:
+      chainedAssertion: hasNext
+      assertToReplace: isFalse
+      dedicatedAssertion: isExhausted
+      requiredType: java.util.Iterator
 
 ---
 type: specs.openrewrite.org/v1beta/recipe

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

@@ -0,0 +1,86 @@
+/*
+ * 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.junit.jupiter.api.Test;
+import org.openrewrite.DocumentExample;
+import org.openrewrite.InMemoryExecutionContext;
+import org.openrewrite.java.JavaParser;
+import org.openrewrite.test.RecipeSpec;
+import org.openrewrite.test.RewriteTest;
+
+import static org.openrewrite.java.Assertions.java;
+
+class IsEqualToBooleanTest implements RewriteTest {
+
+    @Override
+    public void defaults(RecipeSpec spec) {
+        spec
+          .parser(JavaParser.fromJavaVersion().classpathFromResources(new InMemoryExecutionContext(), "assertj-core-3.24"))
+          .recipe(new IsEqualToBoolean());
+    }
+
+    @DocumentExample
+    @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();
+                  }
+              }
+              """
+          )
+        );
+    }
+}

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

@@ -0,0 +1,61 @@
+/*
+ * 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.junit.jupiter.api.Test;
+import org.openrewrite.DocumentExample;
+import org.openrewrite.InMemoryExecutionContext;
+import org.openrewrite.java.JavaParser;
+import org.openrewrite.test.RecipeSpec;
+import org.openrewrite.test.RewriteTest;
+
+import static org.openrewrite.java.Assertions.java;
+
+class IsEqualToEmptyStringTest implements RewriteTest {
+
+    @Override
+    public void defaults(RecipeSpec spec) {
+        spec
+          .parser(JavaParser.fromJavaVersion().classpathFromResources(new InMemoryExecutionContext(), "assertj-core-3.24"))
+          .recipe(new IsEqualToEmptyString());
+    }
+
+    @DocumentExample
+    @Test
+    void convertsIsEqualToEmptyString() {
+        rewriteRun(
+          // language=java
+          java(
+            """
+            import static org.assertj.core.api.Assertions.assertThat;
+            class Test {
+                void test() {
+                    assertThat("test").isEqualTo("");
+                }
+            }
+            """,
+            """
+            import static org.assertj.core.api.Assertions.assertThat;
+            class Test {
+                void test() {
+                    assertThat("test").isEmpty();
+                }
+            }
+            """
+          )
+        );
+    }
+}