src/main/java/org/junit/contrib/truth/subjects/Subject.java

/*
 * Copyright (c) 2011 David Saff
 * Copyright (c) 2011 Christian Gruber
 * 
 * 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 org.junit.contrib.truth.subjects;

import org.junit.contrib.truth.FailureStrategy;

public class Subject<T> {
  private final FailureStrategy failureStrategy;
  private final T subject;

  public Subject(FailureStrategy failureStrategy, T subject) {
    this.failureStrategy = failureStrategy;
    this.subject = subject;
  }

  public Subject<T> is(Object other) {

    if (getSubject() == null) { 
      if(other != null) {
        fail("is", other);
      }
    } else {
      if (!getSubject().equals(other)) {
        fail("is", other);
      }
    }
    return this;
  }

  public Subject<T> isNull() {
    if (getSubject() != null) {
      failWithoutSubject("is null");
    }
    return this;
  }
  
  public Subject<T> isNotNull() {
    if (getSubject() == null) {
      failWithoutSubject("is not null");
    }
    return this;
  }

  public Subject<T> isEqualTo(Object other) {
    if (getSubject() == null) { 
      if(other != null) {
        fail("is equal to", other);
      }
    } else {
      if (!getSubject().equals(other)) {
        fail("is equal to", other);
      }
    }
    return this;
  }

  public Subject<T> isNotEqualTo(Object other) {
    if (getSubject() == null) { 
      if(other == null) {
        fail("is not equal to", other);
      }
    } else {
      if (getSubject().equals(other)) {
        fail("is not equal to", other);
      }
    }
    return this;
  }

  protected T getSubject() {
    return subject;
  }

  protected void fail(String verb, Object... messageParts) {
    String message = "Not true that ";
    message += "<" + getSubject() + "> " + verb;
    for (Object part : messageParts) {
      message += " <" + part + ">";
    }
    failureStrategy.fail(message);
  }
  
  protected void failWithoutSubject(String verb) {
    String message = "Not true that ";
    message += "the subject " + verb;
    failureStrategy.fail(message);
  }
}