code: package com.beijunyi.parallelgit.filesystem.commands;
  
  import java.io.IOException;
  
  import com.beijunyi.parallelgit.AbstractParallelGitTest;
  import com.beijunyi.parallelgit.filesystem.GitFileSystem;
  import com.beijunyi.parallelgit.filesystem.ParallelGitMergeTest;
  import com.beijunyi.parallelgit.filesystem.commands.GfsMerge.Result;
  import com.beijunyi.parallelgit.filesystem.merge.MergeNote;
  import org.eclipse.jgit.lib.ObjectId;
  import org.junit.After;
  import org.junit.Before;
  import org.junit.Test;
  
  import static com.beijunyi.parallelgit.filesystem.Gfs.*;
  import static java.nio.file.Files.exists;
  import static org.junit.Assert.*;
  
  public class GfsMergeSquashTest extends AbstractParallelGitTest implements ParallelGitMergeTest {
  
    private GitFileSystem gfs;
  
    @Before
    public void setUp() throws IOException {
      initRepository();
      ObjectId base = commit();
      clearCache();
      writeToCache("/test_file.txt", "OUR VERSION");
      commitToBranch(OURS, base);
      clearCache();
      writeToCache("/their_file1.txt");
      commitToBranch(THEIRS, base);
      writeToCache("/their_file2.txt");
      commitToBranch(THEIRS);
      gfs = newFileSystem(OURS, repo);
    }
  
    @After
    public void tearDown() throws IOException {
      if(gfs != null) {
        gfs.close();
        gfs = null;
      }
    }
  
    @Test
    public void mergeWithSquashOption_getCommitShouldReturnNull() throws IOException {
      Result result = merge(gfs).source(THEIRS).squash(true).execute();
  
      assertTrue(result.isSuccessful());
      assertNull(result.getCommit());
    }
  
    @Test
    public void mergeWithSquashOption_headCommitShouldRemainTheSame() throws IOException {
      ObjectId head = gfs.getStatusProvider().commit();
      Result result = merge(gfs).source(THEIRS).squash(true).execute();
  
      assertTrue(result.isSuccessful());
      assertEquals(head, gfs.getStatusProvider().commit());
    }
  
    @Test
    public void mergeWithSquashOption_filesFromTheSquashedCommitsShouldExistInTheFileSystem() throws IOException {
      Result result = merge(gfs).source(THEIRS).squash(true).execute();
  
      assertTrue(result.isSuccessful());
      assertTrue(exists(gfs.getPath("/their_file1.txt")));
      assertTrue(exists(gfs.getPath("/their_file2.txt")));
    }
  
    @Test
    public void mergeWithSquashOption_fileSystemShouldHaveMergeNoteWithMessageAndNoSourceCommit() throws IOException {
      Result result = merge(gfs).source(THEIRS).squash(true).execute();
      MergeNote note = gfs.getStatusProvider().mergeNote();
  
      assertTrue(result.isSuccessful());
      assertNotNull(note);
      assertNull(note.getSource());
      assertNotNull(note.getMessage());
    }
  
    @Test
    public void mergeConflictingBranchWithSquashOption_fileSystemShouldHaveMergeNoteWithMessageAndNoSourceCommit() throws IOException {
      writeToCache("/test_file.txt", "THEIR VERSION");
      commitToBranch(THEIRS);
      Result result = merge(gfs).source(THEIRS).squash(true).execute();
      MergeNote note = gfs.getStatusProvider().mergeNote();
  
      assertFalse(result.isSuccessful());
      assertNotNull(note);
      assertNull(note.getSource());
      assertNotNull(note.getMessage());
    }
  
  }
  