test: add tests using git (pypa#347)

git is isolated using the following environment, which are set globally
for the duration of that the new pytest fixture "tmp_git" is used:

GIT_CONFIG_GLOBAL
GIT_CONFIG_NOSYSTEM
HOME
GIT_AUTHOR_EMAIL
GIT_AUTHOR_NAME
GIT_AUTHOR_DATE
GIT_COMMITTER_EMAIL
GIT_COMMITTER_NAME
GIT_COMMITTER_DATE

GIT_DIR and GIT_WORK_TREE could be set so that git can be called using
any method, but instead a git() function is added that uses git's -C
command-line option.

These were taken from one of git's test scripts:
https://github.com/git/git/blob/cefe983a320c03d7843ac78e73bd513a27806845/t/test-lib.sh#L454-L461

There are probably other ways git can be isolated.

The repository is initialized with an empty commit, but this isn't
strictly necessary, it just makes some of the possible tests require
less setup.

The new tmp_project fixture copies the sample module from
./test/samples/module1_toml to the project and commits the files.

A test is added for pypa#345 as an example of how this can be used.

A pytest marker is added so that tests with either "needgit" or
"needsgit" in the name are skipped if python can't find an executable
named "git".

The tox configuration is changed and another pytest marker is added so
that those tests can be run by themselves:

tox -- -m needgit

or skipped:

tox -- -m "not needgit"

Type hints were added to help with development, but aren't necessary to
keep.

pyproject.toml

@@ -42,3 +42,9 @@ Source = "https://github.com/takluyver/flit"
 
 [project.scripts]
 flit = "flit:main"
+
+[tool.pytest.ini_options]
+markers = [
+    "needgit: needs git to be installed in order to run",
+    "needsgit: needs git to be installed in order to run",
+]

tests/conftest.py

@@ -1,15 +1,97 @@
 from pathlib import Path
+from shutil import copy, copytree, which
+from subprocess import check_output
+from typing import TYPE_CHECKING
+from unittest.mock import patch
+
 import pytest
-from shutil import copytree
 
-samples_dir = Path(__file__).parent / 'samples'
+if TYPE_CHECKING:
+    from typing import Iterator, List, Union
+
+samples_dir = Path(__file__).parent / "samples"
+
+skip_if_no_git = pytest.mark.skipif(
+    (not which("git")),
+    reason="needs git to be installed and findable through the PATH environment variable",
+)
+
+
+def pytest_collection_modifyitems(items):
+    for item in items:
+        if "needgit" in item.nodeid or "needsgit" in item.nodeid:
+            item.add_marker(skip_if_no_git)
+            item.add_marker(pytest.mark.needgit)
+            item.add_marker(pytest.mark.needsgit)
+
 
 @pytest.fixture
 def copy_sample(tmp_path):
     """Copy a subdirectory from the samples dir to a temp dir"""
+
     def copy(dirname):
         dst = tmp_path / dirname
         copytree(str(samples_dir / dirname), str(dst))
         return dst
 
     return copy
+
+
+def git(repo: Path, command: "Union[List[str], str]") -> bytes:
+    if isinstance(command, str):
+        args = command.split()
+    else:
+        args = command
+
+    return check_output(
+        ["git", "-C", str(repo), *args],
+    )
+
+
+@pytest.fixture
+def tmp_git(tmp_path: Path) -> "Iterator[Path]":
+    """
+    Make a git repository in a temporary folder
+
+    The path returned is what should be passed to git's -C command, or what cwd
+    should be set to in subprocess calls
+    """
+    git_global_config = tmp_path / "git_global_config"
+    git_global_config.touch(exist_ok=False)
+    repository = tmp_path / "repository"
+    repository.mkdir(exist_ok=False)
+    with patch.dict(
+        "os.environ",
+        {
+            # https://git-scm.com/docs/git#Documentation/git.txt-codeGITCONFIGGLOBALcode
+            "GIT_CONFIG_GLOBAL": str(git_global_config),
+            # https://git-scm.com/docs/git#Documentation/git.txt-codeGITCONFIGNOSYSTEMcode
+            "GIT_CONFIG_NOSYSTEM": "true",
+            "HOME": str(tmp_path),
+            # tox by default only passes the PATH environment variable, so
+            # XDG_CONFIG_HOME is already unset
+            # https://github.com/git/git/blob/cefe983a320c03d7843ac78e73bd513a27806845/t/test-lib.sh#L454-L461
+            "GIT_AUTHOR_EMAIL": "author@example.com",
+            "GIT_AUTHOR_NAME": "A U Thor",
+            "GIT_AUTHOR_DATE": "1112354055 +0200",
+            "GIT_COMMITTER_EMAIL": "committer@example.com",
+            "GIT_COMMITTER_NAME": "committer",
+            "GIT_COMMITTER_DATE": "1112354055 +0200",
+        },
+    ):
+        git(repository, "config --global init.defaultBranch main")
+        git(repository, ["init"])
+        git(repository, "commit --allow-empty --allow-empty-message --no-edit")
+
+        yield repository
+
+
+@pytest.fixture
+def tmp_project(tmp_git: Path) -> "Iterator[Path]":
+    "return a path to the root of a git repository containing a sample package"
+    for file in (samples_dir / "module1_toml").glob("*"):
+        copy(str(file), str(tmp_git / file.name))
+    git(tmp_git, "add -A :/")
+    git(tmp_git, "commit --allow-empty --allow-empty-message --no-edit")
+
+    yield tmp_git

tests/test_build.py

@@ -5,6 +5,7 @@
 from tempfile import TemporaryDirectory
 from testpath import assert_isdir, MockCommand
 
+from .conftest import git
 from flit_core import common
 from flit import build
 
@@ -69,3 +70,11 @@ def test_build_module_no_docstring():
             with pytest.raises(common.NoDocstringError) as exc_info:
                 build.main(pyproject)
             assert 'no_docstring.py' in str(exc_info.value)
+
+def test_build_needgit_unicode_filenames(tmp_project: Path) -> None:
+    "does a package build if it includes a unicode filename?"
+    noel_file = tmp_project / "No\N{LATIN SMALL LETTER E WITH DIAERESIS}l"
+    noel_file.touch()
+    git(tmp_project, "add -A :/")
+    git(tmp_project, "commit --allow-empty --allow-empty-message --no-edit")
+    build.main(tmp_project / "pyproject.toml")

tox.ini

@@ -27,7 +27,7 @@ setenv =
     PYTHONPATH = flit_core
 
 commands =
-    python -m pytest --cov=flit --cov=flit_core/flit_core
+    python -m pytest --cov=flit --cov=flit_core/flit_core {posargs}
 
 [testenv:bootstrap]
 skip_install = true