JsonResourceMatcher.java

package test.util;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.hamcrest.Description;
import org.hamcrest.TypeSafeMatcher;

import java.io.IOException;
import java.net.URL;

/**
 * A Matcher that tests that the JSON given as a string is equivalent to
 * the JSON from a string read from a resource.
 */
class JsonResourceMatcher extends TypeSafeMatcher<String> {

    private static final ObjectMapper MAPPER = new ObjectMapper();

    private final JsonNode expected;

    JsonResourceMatcher(final String resourceName) throws IOException {
        final ClassLoader loader = Thread.currentThread().getContextClassLoader();
        final URL resource = loader.getResource(resourceName);
        if (resource == null) {
            throw new IllegalArgumentException("Resource " + resourceName + " was not found.");
        }
        this.expected = MAPPER.readTree(resource);
    }

    @Override
    protected boolean matchesSafely(final String item) {
        final JsonNode actual;
        try {
            actual = MAPPER.readTree(item);
        } catch (final IOException ignored) {
            // TODO - describe failure - response body wasn't valid JSON
            return false;
        }

        return expected.equals(actual);
    }

    @Override
    public void describeTo(final Description description) {
        description.appendText(expected.toString());
    }

}