Introduction to Hamcrest String Matchers

Another week, another blogpost. For those catching on just now, or finding this post using a search engine; I’m writing a series of posts about Hamcrest, a framework for writing test matcher objects, and showing you how to use Hamcrest. While the previous post was about the Core Matchers, the topic of this week is Hamcrest String Matchers.

The Hamcrest String Matchers are the following:
containsString, startsWith, endsWith, equalToIgnoringCase, equalToIgnoringWhitespace, isEmpty, isEmptyOrNull and stringContainsInOrder

Also in this post, I will give an example of all of them in the code block below:

    @Test
    public void testMovieStringMatchers() {
        // Setting up our class to test here.
        Movie movie = new Movie("Charlies Angels");
        movie.setDescription("");
        movie.setDirector(null);
        movie.setStoryLine("The captivating crime-fighting trio who are the masters of disguise, espionage and martial arts.");

        // Checks that the actual result contains the specified String
        assertThat(movie.getTitle(), containsString("Angels"));
        // Checks that the actual result starts with the specified String
        assertThat(movie.getTitle(), startsWith("Charlies"));
        // Checks that the actual result ends with the specified String
        assertThat(movie.getTitle(), endsWith("Angels"));

        // Checks that the actual result equals the specified String, ignoring casing
        assertThat(movie.getTitle(), equalToIgnoringCase("charlies angels"));
        // Beware: this method work different than you would expect, since it doesn't ignore whitespaces: it ignores most of them. Check the Javadoc.
        assertThat(movie.getTitle(), equalToIgnoringWhiteSpace(" charlies  angels   "));

        // Checks that the actual result is an empty String
        assertThat(movie.getDescription(), isEmptyString());
        // Checks that the actual result is null or an empty String
        assertThat(movie.getDirector(), isEmptyOrNullString());

        // Checks that the actual result contains the specified Strings in this sequence
        assertThat(movie.getStoryLine(), stringContainsInOrder(Arrays.asList("The", "trio", "arts")));
    }

@Test

public void testMovieStringMatchers() {

// Setting up our class to test here.

Movie movie = new Movie("Charlies Angels");

movie.setDescription("");

movie.setDirector(null);

movie.setStoryLine("The captivating crime-fighting trio who are the masters of disguise, espionage and martial arts.");

// Checks that the actual result contains the specified String

assertThat(movie.getTitle(), containsString("Angels"));

// Checks that the actual result starts with the specified String

assertThat(movie.getTitle(), startsWith("Charlies"));

// Checks that the actual result ends with the specified String

assertThat(movie.getTitle(), endsWith("Angels"));

// Checks that the actual result equals the specified String, ignoring casing

assertThat(movie.getTitle(), equalToIgnoringCase("charlies angels"));

// Beware: this method work different than you would expect, since it doesn't ignore whitespaces: it ignores most of them. Check the Javadoc.

assertThat(movie.getTitle(), equalToIgnoringWhiteSpace(" charlies angels "));

// Checks that the actual result is an empty String

assertThat(movie.getDescription(), isEmptyString());

// Checks that the actual result is null or an empty String

assertThat(movie.getDirector(), isEmptyOrNullString());

// Checks that the actual result contains the specified Strings in this sequence

assertThat(movie.getStoryLine(), stringContainsInOrder(Arrays.asList("The", "trio", "arts")));

}

Again, the Hamcrest assertions are very clear, and makes your testcode a easier to read an maintain. Enjoy!

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