Merge pull request #118 from RonnyPfannschmidt/git-shallow1.15.0

address #93 - experimental tools for interacting with git shallow clones

4 files changed, 72 insertions, 5 deletions

diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 5523d7f..b78bf2b 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -9,6 +9,9 @@ v1.15.0
 * update trove classifiers
 * fix issue #84: document using the installed package metadata for sphinx
 * fix issue #81: fail more gracious when git/hg are missing
+* address issue #93: provide an experimental api to customize behaviour on shallow git repos
+  a custom parse function may pick pre parse actions to do when using git
+
 
 v1.14.1
 =======
diff --git a/setuptools_scm/git.py b/setuptools_scm/git.py
index b531414..4806bdc 100644
--- a/setuptools_scm/git.py
+++ b/setuptools_scm/git.py
@@ -1,7 +1,7 @@
 from .utils import do_ex, trace, has_command
 from .version import meta
-from os.path import abspath, normcase, realpath
-
+from os.path import abspath, normcase, realpath, isfile, join
+import warnings
 
 FILES_COMMAND = 'git ls-files'
 DEFAULT_DESCRIBE = 'git describe --tags --long --match *.*'
@@ -12,6 +12,7 @@ def _normalized(path):
 
 
 class GitWorkdir(object):
+    """experimental, may change at any time"""
     def __init__(self, path):
         self.path = path
 
@@ -33,6 +34,12 @@ class GitWorkdir(object):
         out, _, _ = self.do_ex("git status --porcelain --untracked-files=no")
         return bool(out)
 
+    def is_shallow(self):
+        return isfile(join(self.path, '.git/shallow'))
+
+    def fetch_shallow(self):
+        self.do_ex("git fetch --unshallow")
+
     def node(self):
         rev_node, _, ret = self.do_ex('git rev-parse --verify --quiet HEAD')
         if not ret:
@@ -43,11 +50,36 @@ class GitWorkdir(object):
         return revs.count('\n') + 1
 
 
-def parse(root, describe_command=DEFAULT_DESCRIBE):
+def warn_on_shallow(wd):
+    """experimental, may change at any time"""
+    if wd.is_shallow():
+        warnings.warn('"%s" is shallow and may cause errors' % (wd.path,))
+
+
+def fetch_on_shallow(wd):
+    """experimental, may change at any time"""
+    if wd.is_shallow():
+        warnings.warn('"%s" was shallow, git fetch was used to rectify')
+        wd.fetch_shallow()
+
+
+def fail_on_shallow(wd):
+    """experimental, may change at any time"""
+    if wd.is_shallow():
+        raise ValueError(
+            '%r is shallow, please correct with '
+            '"git fetch --unshallow"' % wd.path)
+
+
+def parse(root, describe_command=DEFAULT_DESCRIBE, pre_parse=warn_on_shallow):
+    """
+    :param pre_parse: experimental pre_parse action, may change at any time
+    """
     if not has_command('git'):
         return
     wd = GitWorkdir(root)
-
+    if pre_parse:
+        pre_parse(wd)
     rev_node = wd.node()
     dirty = wd.is_dirty()
 
diff --git a/testing/conftest.py b/testing/conftest.py
index 724e3ca..78a7c1f 100644
--- a/testing/conftest.py
+++ b/testing/conftest.py
@@ -63,4 +63,4 @@ class Wd(object):
 
 @pytest.fixture
 def wd(tmpdir):
-    return Wd(tmpdir)
+    return Wd(tmpdir.ensure('wd', dir=True))
diff --git a/testing/test_git.py b/testing/test_git.py
index 7179a57..8a48b73 100644
--- a/testing/test_git.py
+++ b/testing/test_git.py
@@ -1,4 +1,6 @@
 from setuptools_scm import integration
+from setuptools_scm.utils import do
+from setuptools_scm import git
 import pytest
 from datetime import date
 
@@ -54,6 +56,36 @@ def test_git_dirty_notag(wd):
     assert today.strftime('.d%Y%m%d') in wd.version
 
 
+@pytest.fixture
+def shallow_wd(wd, tmpdir):
+    wd.commit_testfile()
+    wd.commit_testfile()
+    wd.commit_testfile()
+    target = tmpdir.join('wd_shallow')
+    do(['git', 'clone', "file://%s" % wd.cwd, str(target,), '--depth=1'])
+    return target
+
+
+def test_git_parse_shallow_warns(shallow_wd, recwarn):
+    git.parse(str(shallow_wd))
+    msg = recwarn.pop()
+    assert 'is shallow and may cause errors' in str(msg.message)
+
+
+def test_git_parse_shallow_fail(shallow_wd):
+    with pytest.raises(ValueError) as einfo:
+        git.parse(str(shallow_wd), pre_parse=git.fail_on_shallow)
+
+    assert 'git fetch' in str(einfo.value)
+
+
+def test_git_shallow_autocorrect(shallow_wd, recwarn):
+    git.parse(str(shallow_wd), pre_parse=git.fetch_on_shallow)
+    msg = recwarn.pop()
+    assert 'git fetch was used to rectify' in str(msg.message)
+    git.parse(str(shallow_wd), pre_parse=git.fail_on_shallow)
+
+
 def test_find_files_stop_at_root_git(wd):
     wd.commit_testfile()
     wd.cwd.ensure('project/setup.cfg')