How to use appendValue method of org.hamcrest.Description.NullDescription class

1public final class org.hamcrest.Description$NullDescription implements org.hamcrest.Description {
2  public org.hamcrest.Description$NullDescription();
3  public org.hamcrest.Description appendDescriptionOf(org.hamcrest.SelfDescribing);
4  public org.hamcrest.Description appendList(java.lang.String, java.lang.String, java.lang.String, java.lang.Iterable<? extends org.hamcrest.SelfDescribing>);
5  public org.hamcrest.Description appendText(java.lang.String);
6  public org.hamcrest.Description appendValue(java.lang.Object);
7  public <T> org.hamcrest.Description appendValueList(java.lang.String, java.lang.String, java.lang.String, T...);
8  public <T> org.hamcrest.Description appendValueList(java.lang.String, java.lang.String, java.lang.String, java.lang.Iterable<T>);
9  public java.lang.String toString();
10}
11

Source: Description$NullDescription.java

public final class org.hamcrest.Description$NullDescription implements org.hamcrest.Description {
  public org.hamcrest.Description$NullDescription();
  public org.hamcrest.Description appendDescriptionOf(org.hamcrest.SelfDescribing);
  public org.hamcrest.Description appendList(java.lang.String, java.lang.String, java.lang.String, java.lang.Iterable<? extends org.hamcrest.SelfDescribing>);
  public org.hamcrest.Description appendText(java.lang.String);
  public org.hamcrest.Description appendValue(java.lang.Object);
  public <T> org.hamcrest.Description appendValueList(java.lang.String, java.lang.String, java.lang.String, T...);
  public <T> org.hamcrest.Description appendValueList(java.lang.String, java.lang.String, java.lang.String, java.lang.Iterable<T>);
  public java.lang.String toString();
}

1package org.hamcrest;
2
3import org.hamcrest.internal.ReflectiveTypeFinder;
4
5
6/**
7 * Convenient base class for Matchers that require a non-null value of a specific type
8 * and that will report why the received value has been rejected.
9 * This implements the null check, checks the type and then casts. 
10 * To use, implement <pre>matchesSafely()</pre>. 
11 *
12 * @param <T>
13 * @author Neil Dunn
14 * @author Nat Pryce
15 * @author Steve Freeman
16 */
17public abstract class TypeSafeDiagnosingMatcher<T> extends BaseMatcher<T> {
18    private static final ReflectiveTypeFinder TYPE_FINDER = new ReflectiveTypeFinder("matchesSafely", 2, 0); 
19    private final Class<?> expectedType;
20
21    /**
22     * Subclasses should implement this. The item will already have been checked
23     * for the specific type and will never be null.
24     */
25    protected abstract boolean matchesSafely(T item, Description mismatchDescription);
26
27    /**
28     * Use this constructor if the subclass that implements <code>matchesSafely</code> 
29     * is <em>not</em> the class that binds &lt;T&gt; to a type. 
30     * @param expectedType The expectedType of the actual value.
31     */
32    protected TypeSafeDiagnosingMatcher(Class<?> expectedType) {
33      this.expectedType = expectedType;
34    }
35
36    /**
37     * Use this constructor if the subclass that implements <code>matchesSafely</code> 
38     * is <em>not</em> the class that binds &lt;T&gt; to a type. 
39     * @param typeFinder A type finder to extract the type
40     */
41    protected TypeSafeDiagnosingMatcher(ReflectiveTypeFinder typeFinder) {
42      this.expectedType = typeFinder.findExpectedType(getClass()); 
43    }
44
45    /**
46     * The default constructor for simple sub types
47     */
48    protected TypeSafeDiagnosingMatcher() {
49      this(TYPE_FINDER); 
50    }
51
52    @Override
53    @SuppressWarnings("unchecked")
54    public final boolean matches(Object item) {
55        return item != null
56            && expectedType.isInstance(item)
57            && matchesSafely((T) item, new Description.NullDescription());
58    }
59
60    @SuppressWarnings("unchecked")
61    @Override
62    public final void describeMismatch(Object item, Description mismatchDescription) {
63      if (item == null) {
64        mismatchDescription.appendText("was null");
65    } else if (!expectedType.isInstance(item)) {
66      mismatchDescription.appendText("was ")
67            .appendText(item.getClass().getSimpleName())
68            .appendText(" ")
69            .appendValue(item);
70    } else {
71        matchesSafely((T) item, mismatchDescription);
72      }
73    }
74}
75

Source: TypeSafeDiagnosingMatcher.java

package org.hamcrest;

import org.hamcrest.internal.ReflectiveTypeFinder;


/**
 * Convenient base class for Matchers that require a non-null value of a specific type
 * and that will report why the received value has been rejected.
 * This implements the null check, checks the type and then casts. 
 * To use, implement <pre>matchesSafely()</pre>. 
 *
 * @param <T>
 * @author Neil Dunn
 * @author Nat Pryce
 * @author Steve Freeman
 */
public abstract class TypeSafeDiagnosingMatcher<T> extends BaseMatcher<T> {
    private static final ReflectiveTypeFinder TYPE_FINDER = new ReflectiveTypeFinder("matchesSafely", 2, 0); 
    private final Class<?> expectedType;

    /**
     * Subclasses should implement this. The item will already have been checked
     * for the specific type and will never be null.
     */
    protected abstract boolean matchesSafely(T item, Description mismatchDescription);

    /**
     * Use this constructor if the subclass that implements <code>matchesSafely</code> 
     * is <em>not</em> the class that binds &lt;T&gt; to a type. 
     * @param expectedType The expectedType of the actual value.
     */
    protected TypeSafeDiagnosingMatcher(Class<?> expectedType) {
      this.expectedType = expectedType;
    }

    /**
     * Use this constructor if the subclass that implements <code>matchesSafely</code> 
     * is <em>not</em> the class that binds &lt;T&gt; to a type. 
     * @param typeFinder A type finder to extract the type
     */
    protected TypeSafeDiagnosingMatcher(ReflectiveTypeFinder typeFinder) {
      this.expectedType = typeFinder.findExpectedType(getClass()); 
    }

    /**
     * The default constructor for simple sub types
     */
    protected TypeSafeDiagnosingMatcher() {
      this(TYPE_FINDER); 
    }

    @Override
    @SuppressWarnings("unchecked")
    public final boolean matches(Object item) {
        return item != null
            && expectedType.isInstance(item)
            && matchesSafely((T) item, new Description.NullDescription());
    }

    @SuppressWarnings("unchecked")
    @Override
    public final void describeMismatch(Object item, Description mismatchDescription) {
      if (item == null) {
        mismatchDescription.appendText("was null");
    } else if (!expectedType.isInstance(item)) {
      mismatchDescription.appendText("was ")
            .appendText(item.getClass().getSimpleName())
            .appendText(" ")
            .appendValue(item);
    } else {
        matchesSafely((T) item, mismatchDescription);
      }
    }
}