src/test/java/com/google/devtools/build/android/PathsSubject.java

// Copyright 2017 The Bazel Authors. All rights reserved.
//
// 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.google.devtools.build.android;

import static com.google.common.truth.Truth.assertThat;

import com.google.common.base.Joiner;
import com.google.common.truth.FailureStrategy;
import com.google.common.truth.Subject;
import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Arrays;
import java.util.List;
import javax.annotation.Nullable;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Document;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

/** A testing utility that allows assertions against Paths. */
public class PathsSubject extends Subject<PathsSubject, Path> {

  PathsSubject(FailureStrategy failureStrategy, @Nullable Path subject) {
    super(failureStrategy, subject);
  }

  void exists() {
    if (getSubject() == null) {
      fail("should not be null.");
    }
    if (!Files.exists(getSubject())) {
      fail("exists.");
    }
  }

  void xmlContentsIsEqualTo(String... contents) {
    if (getSubject() == null) {
      fail("should not be null.");
    }
    exists();
    try {
      DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
      Transformer transformer = TransformerFactory.newInstance().newTransformer();
      transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
      transformer.setOutputProperty(OutputKeys.INDENT, "no");

      assertThat(
              normalizeXml(
                  newXmlDocument(factory, Files.readAllLines(getSubject(), StandardCharsets.UTF_8)),
                  transformer))
          .isEqualTo(normalizeXml(newXmlDocument(factory, Arrays.asList(contents)), transformer));
    } catch (IOException | SAXException | ParserConfigurationException | TransformerException e) {
      fail(e.toString());
    }
  }

  private Document newXmlDocument(DocumentBuilderFactory factory, List<String> contents)
      throws SAXException, IOException, ParserConfigurationException {
    return factory
        .newDocumentBuilder()
        .parse(new InputSource(new StringReader(Joiner.on("").join(contents))));
  }

  private String normalizeXml(Document doc, Transformer transformer) throws TransformerException {
    StringWriter writer = new StringWriter();
    transformer.transform(new DOMSource(doc), new StreamResult(writer));
    return writer.toString().replaceAll("\n|\r", "").replaceAll(">\\s+<", "><");
  }
}