com.shazam.shazamcrest.matcher.DiagnosingCustomisableMatcher.java Source code

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Here is the source code for com.shazam.shazamcrest.matcher.DiagnosingCustomisableMatcher.java

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/*
 * Copyright 2013 Shazam Entertainment Limited
 * 
 * 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 com.shazam.shazamcrest.matcher;

import static com.shazam.shazamcrest.BeanFinder.findBeanAt;
import static com.shazam.shazamcrest.FieldsIgnorer.findPaths;
import static com.shazam.shazamcrest.GsonProvider.gson;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import org.hamcrest.Description;
import org.hamcrest.DiagnosingMatcher;
import org.hamcrest.Matcher;
import org.json.JSONException;
import org.skyscreamer.jsonassert.JSONAssert;

import com.google.gson.Gson;
import com.google.gson.JsonElement;
import com.google.gson.JsonParser;
import com.shazam.shazamcrest.ComparisonDescription;

/**
 * Extends the functionalities of {@link DiagnosingMatcher} with the possibility to specify fields and object types to
 * ignore in the comparison, or fields to be matched with a custom matcher
 */
class DiagnosingCustomisableMatcher<T> extends DiagnosingMatcher<T> implements CustomisableMatcher<T> {
    private static final JsonParser jsonParser = new JsonParser();

    private final Set<String> pathsToIgnore = new HashSet<String>();
    private final Map<String, Matcher<?>> customMatchers = new HashMap<String, Matcher<?>>();
    protected final List<Class<?>> typesToIgnore = new ArrayList<Class<?>>();
    protected final T expected;

    public DiagnosingCustomisableMatcher(T expected) {
        this.expected = expected;
    }

    @Override
    public void describeTo(Description description) {
        Gson gson = gson(typesToIgnore);
        description.appendText(filterJson(gson, gson.toJson(expected)));
        for (String fieldPath : customMatchers.keySet()) {
            description.appendText("\nand ").appendText(fieldPath).appendText(" ")
                    .appendDescriptionOf(customMatchers.get(fieldPath));
        }
    }

    @Override
    protected boolean matches(Object actual, Description mismatchDescription) {
        Gson gson = gson(typesToIgnore);
        String expectedJson = filterJson(gson, gson.toJson(expected));
        String actualJson = filterJson(gson, gson.toJson(actual));

        Map<Object, Matcher<?>> customMatching = new HashMap<Object, Matcher<?>>();
        for (Entry<String, Matcher<?>> entry : customMatchers.entrySet()) {
            Object object = actual == null ? null : findBeanAt(entry.getKey(), actual);
            customMatching.put(object, customMatchers.get(entry.getKey()));
        }

        return assertEquals(expectedJson, actualJson, customMatching, mismatchDescription, gson);
    }

    @Override
    public CustomisableMatcher<T> ignoring(String string) {
        pathsToIgnore.add(string);
        return this;
    }

    @Override
    public CustomisableMatcher<T> ignoring(Class<?> clazz) {
        typesToIgnore.add(clazz);
        return this;
    }

    @Override
    public <V> CustomisableMatcher<T> with(String fieldPath, Matcher<V> matcher) {
        customMatchers.put(fieldPath, matcher);
        return this;
    }

    protected boolean appendMismatchDescription(Description mismatchDescription, String expectedJson,
            String actualJson, String message) {
        if (mismatchDescription instanceof ComparisonDescription) {
            ComparisonDescription shazamMismatchDescription = (ComparisonDescription) mismatchDescription;
            shazamMismatchDescription.setComparisonFailure(true);
            shazamMismatchDescription.setExpected(expectedJson);
            shazamMismatchDescription.setActual(actualJson);
            shazamMismatchDescription.setDifferencesMessage(message);
        }
        mismatchDescription.appendText(message);
        return false;
    }

    private boolean assertEquals(final String expectedJson, String actualJson,
            Map<Object, Matcher<?>> customMatching, Description mismatchDescription, Gson gson) {
        try {
            for (Entry<Object, Matcher<?>> entry : customMatching.entrySet()) {
                Matcher<?> matcher = entry.getValue();
                Object actual = entry.getKey();
                if (!matcher.matches(actual)) {
                    appendFieldPath(matcher, mismatchDescription);
                    matcher.describeMismatch(actual, mismatchDescription);
                    appendFieldJsonSnippet(actual, mismatchDescription, gson);
                    return false;
                }
            }
            JSONAssert.assertEquals(expectedJson, actualJson, true);
        } catch (AssertionError e) {
            return appendMismatchDescription(mismatchDescription, expectedJson, actualJson, e.getMessage());
        } catch (JSONException e) {
            return appendMismatchDescription(mismatchDescription, expectedJson, actualJson, e.getMessage());
        }

        return true;
    }

    private void appendFieldJsonSnippet(Object actual, Description mismatchDescription, Gson gson) {
        JsonElement jsonTree = gson.toJsonTree(actual);
        if (!jsonTree.isJsonPrimitive() && !jsonTree.isJsonNull()) {
            mismatchDescription.appendText("\n" + gson.toJson(actual));
        }
    }

    private void appendFieldPath(Matcher<?> matcher, Description mismatchDescription) {
        for (Entry<String, Matcher<?>> entry : customMatchers.entrySet()) {
            if (entry.getValue().equals(matcher)) {
                mismatchDescription.appendText(entry.getKey()).appendText(" ");
            }
        }
    }

    private String filterJson(Gson gson, String unfilteredJson) {
        Set<String> set = new HashSet<String>();
        set.addAll(pathsToIgnore);
        set.addAll(customMatchers.keySet());
        JsonElement filteredJson = findPaths(jsonParser.parse(unfilteredJson), set);

        return gson.toJson(filteredJson);
    }
}