depot_tools/tests/git_squash_branch_test.py

#!/usr/bin/env vpython3
# coding=utf-8
# Copyright 2024 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Tests for git_squash_branch."""

import os
import sys
import unittest

DEPOT_TOOLS_ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
sys.path.insert(0, DEPOT_TOOLS_ROOT)

from testing_support import git_test_utils

import git_squash_branch
import git_common

git_common.TEST_MODE = True


class GitSquashBranchTest(git_test_utils.GitRepoReadWriteTestBase):
    # Empty repo.
    REPO_SCHEMA = """
  """

    def setUp(self):
        super(GitSquashBranchTest, self).setUp()

        # Note: Using the REPO_SCHEMA wouldn't simplify this test so it is not
        #       used.
        #
        # Create a repo with the follow schema
        #
        # main <- branchA <- branchB <- branchC
        #            ^
        #            \ branchD
        #
        # where each branch has 2 commits.

        # The repo is empty. Add the first commit or else most commands don't
        # work, including `git branch`, which doesn't even show the main branch.
        self.repo.git('commit', '-m', 'First commit', '--allow-empty')

        # Create the first branch downstream from `main` with 2 commits.
        self.repo.git('checkout', '-B', 'branchA', '--track', 'main')
        self._createFileAndCommit('fileA1')
        self._createFileAndCommit('fileA2')

        # Create a branch downstream from `branchA` with 2 commits.
        self.repo.git('checkout', '-B', 'branchB', '--track', 'branchA')
        self._createFileAndCommit('fileB1')
        self._createFileAndCommit('fileB2')

        # Create another branch downstream from `branchB` with 2 commits.
        self.repo.git('checkout', '-B', 'branchC', '--track', 'branchB')
        self._createFileAndCommit('fileC1')
        self._createFileAndCommit('fileC2')

        # Create another branch downstream from `branchA` with 2 commits.
        self.repo.git('checkout', '-B', 'branchD', '--track', 'branchA')
        self._createFileAndCommit('fileD1')
        self._createFileAndCommit('fileD2')

    def testGitSquashBranchFailsWithDivergedBranch(self):
        self.assertEqual(self._getCountAheadOfUpstream('branchA'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchB'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchC'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchD'), 2)
        self.repo.git('checkout', 'branchB')
        self._createFileAndCommit('fileB3')
        self.repo.git('checkout', 'branchA')

        # We have now made a state where branchC has diverged from branchB.
        output, _ = self.repo.capture_stdio(git_squash_branch.main, [])
        self.assertIn('some children have diverged', output)

    def testGitSquashBranchRootOnly(self):
        self.assertEqual(self._getCountAheadOfUpstream('branchA'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchB'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchC'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchD'), 2)

        self.repo.git('checkout', 'branchA')
        self.repo.run(git_squash_branch.main, [])

        self.assertEqual(self._getCountAheadOfUpstream('branchA'), 1)
        self.assertEqual(self._getCountAheadOfUpstream('branchB'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchC'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchD'), 2)

    def testGitSquashBranchLeaf(self):
        self.assertEqual(self._getCountAheadOfUpstream('branchA'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchB'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchC'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchD'), 2)

        self.repo.git('checkout', 'branchD')
        self.repo.run(git_squash_branch.main, [])

        self.assertEqual(self._getCountAheadOfUpstream('branchA'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchB'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchC'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchD'), 1)

    def testGitSquashBranchSequential(self):
        self.assertEqual(self._getCountAheadOfUpstream('branchA'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchB'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchC'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchD'), 2)

        self.repo.git('checkout', 'branchA')
        self.repo.run(git_squash_branch.main, [])

        self.assertEqual(self._getCountAheadOfUpstream('branchA'), 1)
        self.assertEqual(self._getCountAheadOfUpstream('branchB'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchC'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchD'), 2)

        self.repo.git('checkout', 'branchB')
        self.repo.run(git_squash_branch.main, [])

        self.assertEqual(self._getCountAheadOfUpstream('branchA'), 1)
        self.assertEqual(self._getCountAheadOfUpstream('branchB'), 1)
        self.assertEqual(self._getCountAheadOfUpstream('branchC'), 2)
        self.assertEqual(self._getCountAheadOfUpstream('branchD'), 2)

    # Creates a file with arbitrary contents and commit it to the current
    # branch.
    def _createFileAndCommit(self, filename):
        with self.repo.open(filename, 'w') as f:
            f.write('content')
        self.repo.git('add', filename)
        self.repo.git_commit('Added file ' + filename)

    # Returns the count of how many commits `branch` is ahead of its upstream.
    def _getCountAheadOfUpstream(self, branch):
        upstream = branch + '@{u}'
        output = self.repo.git('rev-list', '--count',
                               upstream + '..' + branch).stdout
        return int(output)


if __name__ == '__main__':
    unittest.main()