TruthConstantAsserts
Truth Library assert is called on a constant.

Category
Severity
WARNING
Maturity

The problem

The arguments to assertThat method is a constant. It should be a variable or a method invocation. For eg. switch assertThat(1).isEqualTo(methodCall()) to assertThat(methodCall()).isEqualTo(1).

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("TruthConstantAsserts") to the enclosing element.


Positive examples

TruthConstantAssertsPositiveCases.java

/*
* Copyright 2016 Google Inc. All Rights Reserved.
*
* 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
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* 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 com.google.errorprone.bugpatterns.testdata;

import static com.google.common.truth.Truth.assertThat;

/**
* Positive test cases for TruthConstantAsserts check.
*
* @author bhagwani@google.com (Sumit Bhagwani)
*/

public class TruthConstantAssertsPositiveCases {

public void testAssertThat() {
// BUG: Diagnostic contains: assertThat(new TruthConstantAssertsPositiveCases()).isEqualTo(1);
assertThat(1).isEqualTo(new TruthConstantAssertsPositiveCases());

// BUG: Diagnostic contains: assertThat(someStaticMethod()).isEqualTo("my string");
assertThat("my string").isEqualTo(someStaticMethod());

// BUG: Diagnostic contains: assertThat(memberMethod()).isEqualTo(42);
assertThat(42).isEqualTo(memberMethod());

// BUG: Diagnostic contains: assertThat(someStaticMethod()).isEqualTo(42L);
assertThat(42L).isEqualTo(someStaticMethod());

// BUG: Diagnostic contains: assertThat(new Object()).isEqualTo(4.2);
assertThat(4.2).isEqualTo(new Object());
}

private static TruthConstantAssertsPositiveCases someStaticMethod() {
return new TruthConstantAssertsPositiveCases();
}

private TruthConstantAssertsPositiveCases memberMethod() {
return new TruthConstantAssertsPositiveCases();
}
}

Negative examples

TruthConstantAssertsNegativeCases.java

/*
* Copyright 2016 Google Inc. All Rights Reserved.
*
* 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
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* 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 com.google.errorprone.bugpatterns.testdata;

import static com.google.common.truth.Truth.assertThat;

/**
* Negative test cases for TruthConstantAsserts check.
*
* @author bhagwani@google.com (Sumit Bhagwani)
*/

public class TruthConstantAssertsNegativeCases {

public void testNegativeCases() {
assertThat(new TruthConstantAssertsNegativeCases()).isEqualTo(Boolean.TRUE);
assertThat(getObject()).isEqualTo(Boolean.TRUE);

// assertion called on constant with constant expectation is ignored.
assertThat(Boolean.FALSE).isEqualTo(4.2);
}

private static TruthConstantAssertsNegativeCases getObject() {
return new TruthConstantAssertsNegativeCases();
}
}