public void testHeadNotPopular() throws Exception {
    VersionCounts versionCounts = VersionCounts.make();

    VoteBlock vb1 = makeVoteBlock("http://test.com/foo1");
    byte[] hash1 = addVersion(vb1, "content 1 for foo1");
    byte[] hash2 = addVersion(vb1, "content 2 for foo1");

    VoteBlock vb2 = makeVoteBlock("http://test.com/foo1");
    addVersion(vb2, "content 1 for foo1");
    addVersion(vb2, "content 2 for foo1");

    VoteBlock vb3 = makeVoteBlock("http://test.com/foo1");
    addVersion(vb3, "content 3 for foo1");
    addVersion(vb3, "content 2 for foo1");

    versionCounts.vote(vb1, participant1);
    versionCounts.vote(vb2, participant2);
    versionCounts.vote(vb3, participant3);

    Map<ParticipantUserData, HashResult> repairCandidates;
    repairCandidates = versionCounts.getRepairCandidates(0);
    assertSameElements(
        SetUtil.set(participant1, participant2, participant3), repairCandidates.keySet());

    repairCandidates = versionCounts.getRepairCandidates(1);
    assertSameElements(
        SetUtil.set(participant1, participant2, participant3), repairCandidates.keySet());

    repairCandidates = versionCounts.getRepairCandidates(2);
    assertSameElements(SetUtil.set(participant1, participant2), repairCandidates.keySet());

    repairCandidates = versionCounts.getRepairCandidates(3);
    assertEmpty(repairCandidates.keySet());
  }
  public void testMultipleIdenticalVersions() throws Exception {
    VersionCounts versionCounts = VersionCounts.make();

    VoteBlock vb1 = makeVoteBlock("http://test.com/foo1");
    byte[] hash1 = addVersion(vb1, "content 1 for foo1");
    byte[] hash2 = addVersion(vb1, "content 2 for foo1");

    VoteBlock vb2 = makeVoteBlock("http://test.com/foo1");
    addVersion(vb2, "content 1 for foo1");
    addVersion(vb2, "content 1 for foo1");
    addVersion(vb2, "content 1 for foo1");
    addVersion(vb2, "content 1 for foo1");
    addVersion(vb2, "content 2 for foo1");

    VoteBlock vb3 = makeVoteBlock("http://test.com/foo1");
    addVersion(vb3, "content 1 for foo1");
    addVersion(vb3, "content 2 for foo1");
    addVersion(vb3, "content 2 for foo1");
    addVersion(vb3, "content 2 for foo1");
    addVersion(vb3, "content 2 for foo1");

    versionCounts.vote(vb1, participant1);
    versionCounts.vote(vb2, participant2);
    versionCounts.vote(vb3, participant3);

    Map<ParticipantUserData, HashResult> repairCandidates;
    repairCandidates = versionCounts.getRepairCandidates(2);
    assertSameElements(
        SetUtil.set(participant1, participant2, participant3), repairCandidates.keySet());

    // With only three candidates, no version should reach a threshold
    // of 4, unless counting multiples is wrong.
    repairCandidates = versionCounts.getRepairCandidates(4);
    assertEmpty(repairCandidates.keySet());
  }
  public void testHeadNotAllowed() throws Exception {
    VersionCounts versionCounts = VersionCounts.make();

    VoteBlock vb1 = makeVoteBlock("http://test.com/foo1");
    byte[] hash1 = addVersion(vb1, "content 1 for foo1");
    byte[] hash2 = addVersion(vb1, "content 2 for foo1");

    versionCounts.vote(vb1, participant1);

    Map<ParticipantUserData, HashResult> repairCandidates;
    repairCandidates = versionCounts.getRepairCandidates(0);
    assertSameElements(SetUtil.set(participant1), repairCandidates.keySet());

    // Same, but with an excluded version that doesn't matter.
    repairCandidates = versionCounts.getRepairCandidates(0, SetUtil.set(HashResult.make(hash2)));
    assertSameElements(SetUtil.set(participant1), repairCandidates.keySet());

    // Same, but with an excluded version that does matter
    repairCandidates = versionCounts.getRepairCandidates(0, SetUtil.set(HashResult.make(hash1)));
    assertEmpty(repairCandidates);
  }