tests: Add a test for sync with potential conflicts

This is an scenario where GUW sync command raises some git conflicts that
are avoidable:

	* 0632076 (HEAD -> A) foo
	| * b1ac2a0 (B) bar
	| * fd1dd3f foo
	|/
	* 5ccd4f9 (main, final) init

In this scenario the branch A was rebased, hypothetically because a
reviewed asked for a change. Then, when we try to "sync" with GUW, it
launches the command:

	git rebase origin/A B --onto=final

The range "origin/A..B" is wrong, the correct one should be "B~..B" because
it includes **only** the commits within the "B" branch. This command
doesn't raises conflicts and gives the expected result:

	git rebase B~ B --onto=final

Author: carlosfg-flu

tests/test_sync_with_conflicts.py

@@ -0,0 +1,113 @@
+import shutil
+import tempfile
+import unittest
+from pathlib import Path
+
+import git
+import tomli
+
+from guw.main import GUW
+
+class TestSyncWithConflicts(unittest.TestCase):
+    file_name = "file.txt"
+    fc_init = """
+        init
+    """
+    fc_a1 = """
+        init
+        A fo
+    """
+    fc_b = """
+        B bar
+        init
+        A fo
+    """
+    fc_a2 = """
+        init
+        A foo
+    """
+    fc_expected = """
+        B bar
+        init
+        A foo
+    """
+
+    @classmethod
+    def _commit_file(cls, repo, file_path, file_contents, commit_message, *args):
+        with open(file_path, "w") as f:
+            f.write(file_contents)
+        repo.index.add(file_path)
+        repo.git.commit("--message", commit_message, *args)
+
+    @classmethod
+    def _prepare_repo(cls, repo_dir):
+        repo = git.Repo.init(repo_dir)
+        fp = repo_dir / cls.file_name
+
+        cls._commit_file(repo, fp, cls.fc_init, "init")
+        repo.git.branch("final")
+
+        repo.git.checkout("HEAD", b = "A")
+        cls._commit_file(repo, fp, cls.fc_a1, "foo")
+
+        repo.git.checkout("HEAD", b = "B")
+        cls._commit_file(repo, fp, cls.fc_b, "bar")
+        
+        # Reviewer asked for changes: fix and ammend this branch
+        repo.git.checkout("A")
+        cls._commit_file(repo, fp, cls.fc_a2, "foo", "--amend")
+
+    def setUp(self):
+        self.tmpdir = Path(tempfile.mkdtemp())
+        self.guw_dir = self.tmpdir / "guw"
+        self.repo_dir = self.tmpdir / "remote"
+
+        self._prepare_repo(self.repo_dir)
+        config = f"""
+            [[remotes]]
+            name = "origin"
+            url = "file://{self.repo_dir}"
+
+            [target]
+            remote = "origin"
+            branch = "final"
+
+            [source]
+            remote = "origin"
+            branch = "main"
+
+            [[features]]
+            remote = "origin"
+            name = "A"
+            status = "merging"
+
+            [[features]]
+            remote = "origin"
+            name = "B"
+            status = "pending"
+        """
+
+        self.guw = GUW(tomli.loads(config))
+
+    def cleanUp(self):
+        shutil.rmtree(self.tmpdir)
+
+    def check_file_contents(self, repo_path):
+        with open(repo_path / self.file_name) as f:
+            file_contents = f.read()
+        self.assertEqual(self.fc_expected, file_contents)
+
+    def test_sync_with_conflict(self):
+        self.guw.sync(
+            backup = False,
+            keep   = True,
+            local  = True,
+            folder = self.guw_dir,
+        )
+        repo = git.Repo(self.guw_dir)
+        self.check_file_contents(self.guw_dir)
+
+    def test_manual_rebase(self):
+        repo = git.Repo(self.repo_dir)
+        repo.git.rebase("B~", "B", "--onto", "A")
+        self.check_file_contents(self.repo_dir)