Add support for Fossil SCM branch names in vc.py. (xonsh#5046)

Add support for Fossil VCS in vc.py.

The prompt now shows the currently active Fossil branch, while inside a Fossil checkout.

news/vc.rst

@@ -0,0 +1,24 @@
+**Added:**
+
+* Display the current branch of Fossil VCS checkouts in the prompt,
+ similar to git and hg.
+
+**Changed:**
+
+* <news item>
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* <news item>
+
+**Security:**
+
+* <news item>

tests/prompt/test_vc.py

@@ -1,5 +1,7 @@
 import os
 import subprocess as sp
+import textwrap
+from typing import Dict, List
 from pathlib import Path
 from unittest.mock import Mock
 
@@ -8,7 +10,19 @@
 from xonsh.prompt import vc
 
 # Xonsh interaction with version control systems.
-VC_BRANCH = {"git": {"master", "main"}, "hg": {"default"}}
+VC_BRANCH = {
+ "git": {"master", "main"},
+ "hg": {"default"},
+ "fossil": {"trunk"},
+}
+VC_INIT: Dict[str, List[List[str]]] = {
+ # A sequence of commands required to initialize a repository
+ "git": [["init"]],
+ "hg": [["init"]],
+ # Fossil "init" creates a central repository file with the given name,
+ # "open" creates the working directory at another, arbitrary location.
+ "fossil": [["init", "test.fossil"], ["open", "test.fossil"]]
+}
 
 
 @pytest.fixture(params=VC_BRANCH.keys())
@@ -20,28 +34,32 @@ def repo(request, tmpdir_factory):
  temp_dir = Path(tmpdir_factory.mktemp("dir"))
  os.chdir(temp_dir)
  try:
- sp.call([vc, "init"])
+ for init_command in VC_INIT[vc]:
+ sp.call([vc] + init_command)
  except FileNotFoundError:
  pytest.skip(f"cannot find {vc} executable")
  if vc == "git":
- git_config = temp_dir / ".git/config"
- git_config.write_text(
- """
-[user]
-name = me
-email = [email protected]
-[init]
-defaultBranch = main
-"""
- )
-
- # git needs at least one commit
- Path("test-file").touch()
- sp.call(["git", "add", "test-file"])
- sp.call(["git", "commit", "-m", "test commit"])
+ _init_git_repository(temp_dir)
  return {"vc": vc, "dir": temp_dir}
 
 
+def _init_git_repository(temp_dir):
+ git_config = temp_dir / ".git/config"
+ git_config.write_text(textwrap.dedent(
+ """\
+ [user]
+ name = me
+ email = [email protected]
+ [init]
+ defaultBranch = main
+ """
+ ))
+ # git needs at least one commit
+ Path("test-file").touch()
+ sp.call(["git", "add", "test-file"])
+ sp.call(["git", "commit", "-m", "test commit"])
+
+
 @pytest.fixture
 def set_xenv(xession, monkeypatch):
  def _wrapper(path):
@@ -52,8 +70,15 @@ def _wrapper(path):
 
 
 def test_test_repo(repo):
- test_vc_dir = repo["dir"] / ".{}".format(repo["vc"])
- assert test_vc_dir.is_dir()
+ if repo["vc"] == "fossil":
+ # Fossil stores the check-out meta-data in a special file within the open check-out.
+ # At least one of these below must exist
+ metadata_file_names = {".fslckout", "_FOSSIL_"} # .fslckout on Unix, _FOSSIL_ on Windows
+ existing_files = set(file.name for file in repo["dir"].iterdir())
+ assert existing_files.intersection(metadata_file_names)
+ else:
+ test_vc_dir = repo["dir"] / ".{}".format(repo["vc"])
+ assert test_vc_dir.is_dir()
  if repo["vc"] == "git":
  test_file = repo["dir"] / "test-file"
  assert test_file.exists()

xonsh/prompt/vc.py

@@ -124,6 +124,27 @@ def get_hg_branch(root=None):
  return branch
 
 
+def _run_fossil_cmd(cmd):
+ timeout = XSH.env.get("VC_BRANCH_TIMEOUT")
+ result = subprocess.check_output(cmd, stderr=subprocess.DEVNULL, timeout=timeout)
+ return result
+
+
+def get_fossil_branch():
+ """Attempts to find the current fossil branch. If this could not
+ be determined (timeout, not in a fossil checkout, etc.) then this returns None.
+ """
+ # from fossil branch --help: "fossil branch current: Print the name of the branch for the current check-out"
+ cmd = "fossil branch current".split()
+ try:
+ branch = xt.decode_bytes(_run_fossil_cmd(cmd))
+ except (subprocess.CalledProcessError, OSError):
+ branch = None
+ else:
+ branch = RE_REMOVE_ANSI.sub("", branch.splitlines()[0])
+ return branch
+
+
 _FIRST_BRANCH_TIMEOUT = True
 
 
@@ -156,7 +177,7 @@ def _vc_has(binary):
 
 def current_branch():
  """Gets the branch for a current working directory. Returns an empty string
- if the cwd is not a repository. This currently only works for git and hg
+ if the cwd is not a repository. This currently only works for git, hg, and fossil
  and should be extended in the future. If a timeout occurred, the string
  '<branch-timeout>' is returned.
  """
@@ -165,6 +186,8 @@ def current_branch():
  branch = get_git_branch()
  if not branch and _vc_has("hg"):
  branch = get_hg_branch()
+ if not branch and _vc_has("fossil"):
+ branch = get_fossil_branch()
  if isinstance(branch, subprocess.TimeoutExpired):
  branch = "<branch-timeout>"
  _first_branch_timeout_message()
@@ -234,6 +257,20 @@ def hg_dirty_working_directory():
  return None
 
 
+def fossil_dirty_working_directory():
+ """Returns whether the fossil checkout is dirty. If this could not
+ be determined (timeout, file not found, etc.) then this returns None.
+ """
+ cmd = ["fossil", "changes"]
+ try:
+ status = _run_fossil_cmd(cmd)
+ except (subprocess.CalledProcessError, OSError):
+ status = None
+ else:
+ status = bool(status)
+ return status
+
+
 def dirty_working_directory():
  """Returns a boolean as to whether there are uncommitted files in version
  control repository we are inside. If this cannot be determined, returns
@@ -244,6 +281,8 @@ def dirty_working_directory():
  dwd = git_dirty_working_directory()
  if dwd is None and _vc_has("hg"):
  dwd = hg_dirty_working_directory()
+ if dwd is None and _vc_has("fossil"):
+ dwd = fossil_dirty_working_directory()
  return dwd