JUnit on steroids - JUnit in Action - page 434

String str = null ;

D

assertThat( str, isNotNullOrEmpty() );
assertThat( str, is( notNullOrEmpty() ) );
}

@Test(expected=java.lang.AssertionError. class )
public void testIsNotNullOrEmptyButIsEmpty() {
String str = "";

assertThat( str, isNotNullOrEmpty() );
assertThat( str, is( notNullOrEmpty() ) );
}

@Test
public void testIsNotNullOrEmptyIsNotNull() {
String str = "test";
assertThat( str, isNotNullOrEmpty() );
assertThat( str, is( notNullOrEmpty() ) );
}
}
All we need to do is use the static import feature of Java 1.5 and import the matcher
that we want to use B . After that, we implement three test methods using the custom
matcher we just implemented. The first two deliberately test failing conditions, and we
denote this with the expected parameter of the @Test annotation C . We also use the
two factory methods D , the second one in conjunction with one of the core matchers
of Hamcrest.
Now we demonstrate another example of making a custom matcher, this time by
using TypeSafeMatcher<T> . For this case, we implement a custom Hamcrest matcher,
which checks to see if a given password is valid. We consider the password to be valid if
it's longer than six characters, contains a digit, and also contains a special symbol (any
of the following: !, ", #, $, %, &, ', (, ), *, +, -, ., /).
Listing B.10 shows our custom Hamcrest matcher.

Listing B.10 IsStrongPassword custom matcher

[...]
public class IsStrongPassword extends TypeSafeMatcher<String> {
@Override
public boolean matchesSafely( String str ) {
return containsSpecialSymbol( str )
&& containsDigit( str )
&& str.length() >= 6;
}

B

C

D

private boolean containsDigit( String str ) {
for ( char ch : str.toCharArray() ) {
if ( Character.isDigit( ch ) ) {
return true ;
}
}
return false ;
}