我的历史是这样的:

* 3830e61 Add data escaping.              (Bad)
* 0f5e148 Improve function for getting page template.
*   aaf8dc5 Merge branch 'navigation'
|\
| * 3e667f8 Add icons.
| * 43a07b1 Add menu styles.              (Breaks)
| * 107ca95 Add Responsive Nav.           (Good)
* | ea3d736 Add ‘Admin’ notice.
* | 17ca0bb Update placeholder text.
|/
* f52cc34 Add featured image.
* 2abd954 Style placeholders.

我正在尝试了解更多信息和 git bisect，但我在处理这段历史时遇到了麻烦。我知道 107ca95 很好，3830e61 不好。当我运行 git bisect 时，提交 107ca95..3e667f8 被忽略。我碰巧知道 43a07b1 是引入回归的提交，但它从未被评估过。

这是我大致的做法:

git checkout master
git bisect start
git bisect bad
git bisect good 107ca95
git bisect bad (multiple times)

无论我做什么，107ca95..3e667f8 都不会被 check out 进行测试。

有什么方法可以在对分期间基本上“展平”历史以测试这些提交？我知道我可以使用交互式 rebase 来展平历史，但我不想这样做。

最佳答案

这是一个非常古老但没有答案的问题。我决定进行调查，发现我可以证明 Git 的行为与问题所说的不同。 一种解释是 Git 改进了对分算法，或者提问者在标记提交时犯了错误。

I am trying to learn more and git bisect, but am having trouble with this history. I know that 107ca95 is good and 3830e61 is bad. When I run a git bisect, commits 107ca95..3e667f8 are ignored. I happen to know that 43a07b1 is the commit that introduced a regression, but it is never evaluated.

我写了一些代码来检查它是否被评估。我的测试表明它被评估了。运行下面的代码并验证是否出现带有消息 Add menu styles. 的提交。

进一步评论:

• “提交 107ca95..3e667f8 被忽略”:请注意，您标记为“好”的提交将不会被评估，因为 git 已经知道它是好的。
• 请阅读 this article by Christian Couder 中的“二分法算法”部分. “检查 merge 基础”部分也可能相关。
• 如上所述，问题肯定是使用了与我使用的版本不同的版本(问题来自 2013 年，Git 2.11 来自 2016 年)。

平分运行输出

• 请注意，第一个“添加管理员通知”被选中(第 4 行)，因为它提供了最多的信息。 (阅读上述文章中的“检查 merge 基础”。)
• 从那时起，它按预期将线性历史一分为二。

# bad: [d7761d6f146eaca1d886f793ced4315539326866] Add data escaping. (Bad)
# good: [f555d9063a25a20a6ec7c3b0c0504ffe0a997e98] Add Responsive Nav. (Good)
git bisect start 'd7761d6f146eaca1d886f793ced4315539326866' 'f555d9063a25a20a6ec7c3b0c0504ffe0a997e98'
# good: [1b3b7f4952732fec0c68a37d5f313d6f4219e4ae] Add ‘Admin’ notice. (Good)
git bisect good 1b3b7f4952732fec0c68a37d5f313d6f4219e4ae
# bad: [f9a65fe9e6cde4358e5b8ef7569332abfb07675e] Add icons. (Bad)
git bisect bad f9a65fe9e6cde4358e5b8ef7569332abfb07675e
# bad: [165b8a6e5137c40ce8b90911e59d7ec8eec30f46] Add menu styles. (Bad)
git bisect bad 165b8a6e5137c40ce8b90911e59d7ec8eec30f46
# first bad commit: [165b8a6e5137c40ce8b90911e59d7ec8eec30f46] Add menu styles. (Bad)

代码

在 Python 3 中运行，使用 Git 2.11.0。 运行命令:python3 script.py

""" The following code creates a git repository in '/tmp/git-repo' and populates
it with the following commit graph. Each commit has a test.sh which can be used
as input to a git-bisect-run.

The code then tries to find the breaking change automatically.
And prints out the git bisect log.

Written in response to http://stackoverflow.com/questions/17267816/git-bisect-with-merged-commits
to test the claim that '107ca95..3e667f8 are never checked out'.

Needs Python 3!
"""


from itertools import chain
import os.path
import os
import sh

repo = {
0x3830e61:  {'message': "Add data escaping.", 'parents': [    0x0f5e148    ], 'test': False} , # Last:    (Bad)
0x0f5e148: {'message': "Improve function for getting page template.", 'parents': [ 0xaaf8dc5], 'test': False},
0xaaf8dc5: {'message': "Merge branch 'navigation'", 'parents': [ 0x3e667f8, 0xea3d736], 'test': False},
    0x3e667f8: {'message': "Add icons.", 'parents': [  0x43a07b1], 'test': False},
    0x43a07b1: {'message': "Add menu styles.", 'parents': [    0x107ca95], 'test': False}  , # First:       (Breaks)
    0x107ca95: {'message': "Add Responsive Nav.", 'parents': [   0xf52cc34], 'test': True}, # First:        (Good)
  0xea3d736: {'message': "Add ‘Admin’ notice.", 'parents': [ 0x17ca0bb], 'test': True},
  0x17ca0bb: {'message': "Update placeholder text.", 'parents': [  0xf52cc34], 'test': True},
0xf52cc34: {'message': "Add featured image.", 'parents': [  0x2abd954], 'test': True},
0x2abd954: {'message': "Style placeholders.", 'parents': [], 'test': True},
}

bad = 0x3830e61
good = 0x107ca95


def generate_queue(_dag, parents):
    for prev in parents:
        yield prev
        yield from generate_queue(_dag, _dag[prev]['parents'])

def make_queue(_dag, inits):
    """ Converts repo (a DAG) into a queue """
    q = list(generate_queue(_dag, inits))
    q.reverse()
    seen = set()
    r = [x for x in q if not (x in seen or seen.add(x))]
    return r

if __name__ == '__main__':
    pwd = '/tmp/git-repo'
    sh.rm('-r', pwd)
    sh.mkdir('-p', pwd)
    g = sh.git.bake(_cwd=pwd)
    g.init()

    parents = set(chain.from_iterable((repo[c]['parents'] for c in repo)))

    commits = set(repo)
    inits = list(commits - parents)
    queue = make_queue(repo, inits)

    assert len(queue) == len(repo), "queue {} vs repo {}".format(len(queue), len(repo))

    commit_ids = {}
    # Create commits
    for c in queue:
        # Set up repo
        parents = repo[c]['parents']
        if len(parents) > 0:
            g.checkout(commit_ids[parents[0]])
        if len(parents) > 1:
            if len(parents) > 2: raise NotImplementedError('Octopus merges not support yet.')
            g.merge('--no-commit', '-s', 'ours', commit_ids[parents[1]])  # just force to use 'ours' strategy.

        # Make changes
        with open(os.path.join(pwd, 'test.sh'), 'w') as f:
            f.write('exit {:d}\n'.format(0 if repo[c]['test'] else 1))
        os.chmod(os.path.join(pwd, 'test.sh'), 0o0755)
        with open(os.path.join(pwd, 'message'), 'w') as f:
            f.write(repo[c]['message'])
        g.add('test.sh', 'message')
        g.commit('-m', '{msg} ({test})'.format(msg=repo[c]['message'], test='Good' if repo[c]['test'] else 'Bad'))
        commit_ids[c] = g('rev-parse', 'HEAD').strip()

    # Run git-bisect
    g.bisect('start', commit_ids[bad], commit_ids[good])
    g.bisect('run', './test.sh')
    print(g.bisect('log'))

关于Git 将 merge 的提交一分为二，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/17267816/