Merge pull request #119 from RonnyPfannschmidt/fix-81

fix #81 - fail more nice if git/hg is not availiable

Author: RonnyPfannschmidt

CHANGELOG.rst

@@ -8,6 +8,7 @@ v1.15.0
   and ensure its always correctly usign itself
 * 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
 
 v1.14.1
 =======

setuptools_scm/git.py

@@ -1,4 +1,4 @@
-from .utils import do_ex, trace
+from .utils import do_ex, trace, has_command
 from .version import meta
 from os.path import abspath, normcase, realpath
 
@@ -44,6 +44,8 @@ def count_all_nodes(self):
 
 
 def parse(root, describe_command=DEFAULT_DESCRIBE):
+    if not has_command('git'):
+        return
     wd = GitWorkdir(root)
 
     rev_node = wd.node()

setuptools_scm/hg.py

@@ -1,5 +1,5 @@
 import os
-from .utils import do, trace, data_from_mime
+from .utils import do, trace, data_from_mime, has_command
 from .version import meta, tags_to_versions
 
 FILES_COMMAND = 'hg locate -I .'
@@ -23,6 +23,8 @@ def _hg_tagdist_normalize_tagcommit(root, tag, dist, node):
 
 
 def parse(root):
+    if not has_command('hg'):
+        return
     l = do('hg id -i -t', root).split()
     node = l.pop(0)
     tags = tags_to_versions(l)

setuptools_scm/utils.py

@@ -2,6 +2,7 @@
 utils
 """
 from __future__ import print_function, unicode_literals
+import warnings
 import sys
 import shlex
 import subprocess
@@ -41,12 +42,9 @@ def _always_strings(env_dict):
     return env_dict
 
 
-def do_ex(cmd, cwd='.'):
-    trace('cmd', repr(cmd))
-    if not isinstance(cmd, (list, tuple)):
-        cmd = shlex.split(cmd)
+def _popen_pipes(cmd, cwd):
 
-    p = subprocess.Popen(
+    return subprocess.Popen(
         cmd,
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,
@@ -60,6 +58,13 @@ def do_ex(cmd, cwd='.'):
         ))
     )
 
+
+def do_ex(cmd, cwd='.'):
+    trace('cmd', repr(cmd))
+    if not isinstance(cmd, (list, tuple)):
+        cmd = shlex.split(cmd)
+
+    p = _popen_pipes(cmd, cwd)
     out, err = p.communicate()
     if out:
         trace('out', repr(out))
@@ -88,3 +93,17 @@ def data_from_mime(path):
         if ': ' in x)
     trace('data', data)
     return data
+
+
+def has_command(name):
+    try:
+        p = _popen_pipes([name, 'help'], '.')
+    except OSError:
+        trace(*sys.exc_info())
+        res = False
+    else:
+        p.communicate()
+        res = not p.returncode
+    if not res:
+        warnings.warn("%r was not found" % name)
+    return res

testing/test_functions.py

@@ -2,6 +2,7 @@
 import pkg_resources
 from setuptools_scm import dump_version, get_version, PRETEND_KEY
 from setuptools_scm.version import guess_next_version, meta, format_version
+from setuptools_scm.utils import has_command
 
 
 class MockTime(object):
@@ -62,3 +63,9 @@ def test_dump_version_works_with_pretend(tmpdir, monkeypatch):
     monkeypatch.setenv(PRETEND_KEY, '1.0')
     get_version(write_to=str(tmpdir.join('VERSION.txt')))
     assert tmpdir.join('VERSION.txt').read() == '1.0'
+
+
+def test_has_command(recwarn):
+    assert not has_command('yadayada_setuptools_aint_ne')
+    msg = recwarn.pop()
+    assert 'yadayada' in str(msg.message)