AssertTrueNullToAssertNull.java

/*
 * Copyright 2022 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.cleanup;

import org.openrewrite.ExecutionContext;
import org.openrewrite.Preconditions;
import org.openrewrite.Recipe;
import org.openrewrite.TreeVisitor;
import org.openrewrite.java.JavaParser;
import org.openrewrite.java.JavaTemplate;
import org.openrewrite.java.JavaVisitor;
import org.openrewrite.java.MethodMatcher;
import org.openrewrite.java.search.UsesMethod;
import org.openrewrite.java.tree.Expression;
import org.openrewrite.java.tree.J;

public class AssertTrueNullToAssertNull extends Recipe {
    private static final MethodMatcher ASSERT_TRUE = new MethodMatcher(
            "org.junit.jupiter.api.Assertions assertTrue(..)");

    @Override
    public String getDisplayName() {
        return "Replace JUnit `assertTrue(a == null)` to `assertNull(a)`";
    }

    @Override
    public String getDescription() {
        return "Using `assertNull(a)` is simpler and more clear.";
    }

    @Override
    public TreeVisitor<?, ExecutionContext> getVisitor() {
        return Preconditions.check(new UsesMethod<>(ASSERT_TRUE), new JavaVisitor<ExecutionContext>() {
            @Override
            public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext ctx) {
                J.MethodInvocation mi = (J.MethodInvocation) super.visitMethodInvocation(method, ctx);
                if (ASSERT_TRUE.matches(mi) && isEqualBinaryWithNull(mi)) {
                    J.Binary binary = (J.Binary) mi.getArguments().get(0);
                    Expression nonNullExpression = getNonNullExpression(binary);

                    StringBuilder sb = new StringBuilder();
                    if (mi.getSelect() == null) {
                        maybeRemoveImport("org.junit.jupiter.api.Assertions");
                        maybeAddImport("org.junit.jupiter.api.Assertions", "assertNull");
                    } else {
                        sb.append("Assertions.");
                    }
                    sb.append("assertNull(#{any(java.lang.Object)}");

                    Object[] args;
                    if (mi.getArguments().size() == 2) {
                        sb.append(", #{any()}");
                        args = new J[]{nonNullExpression, mi.getArguments().get(1)};
                    } else {
                        args = new J[]{nonNullExpression};
                    }
                    sb.append(")");
                    JavaTemplate t;
                    if (mi.getSelect() == null) {
                        t = JavaTemplate.builder(sb.toString())
                                .contextSensitive()
                                .staticImports("org.junit.jupiter.api.Assertions.assertNull")
                                .javaParser(JavaParser.fromJavaVersion()
                                        .classpathFromResources(ctx, "junit-jupiter-api-5.9"))
                                .build();
                    } else {
                        t = JavaTemplate.builder(sb.toString())
                                .contextSensitive()
                                .imports("org.junit.jupiter.api.Assertions")
                                .javaParser(JavaParser.fromJavaVersion()
                                        .classpathFromResources(ctx, "junit-jupiter-api-5.9"))
                                .build();
                    }
                    return t.apply(updateCursor(mi), mi.getCoordinates().replace(), args);
                }
                return mi;
            }

            private Expression getNonNullExpression(J.Binary binary) {
                if (binary.getRight() instanceof J.Literal) {
                    boolean isNull = ((J.Literal) binary.getRight()).getValue() == null;
                    if (isNull) {
                        return binary.getLeft();
                    }
                }
                return binary.getRight();
            }

            private boolean isEqualBinaryWithNull(J.MethodInvocation method) {
                if (method.getArguments().isEmpty()) {
                    return false;
                }

                final Expression firstArgument = method.getArguments().get(0);
                if (!(firstArgument instanceof J.Binary)) {
                    return false;
                }

                J.Binary binary = (J.Binary) firstArgument;
                if (binary.getOperator() != J.Binary.Type.Equal) {
                    return false;
                }
                return binary.getLeft() instanceof J.Literal && ((J.Literal) binary.getLeft()).getValue() == null ||
                       binary.getRight() instanceof J.Literal && ((J.Literal) binary.getRight()).getValue() == null;
            }
        });
    }
}