GitRepository: implement _cmd_has_feature() method

This method is intended for checking if the local git (client) command
supports a certain feature. The "feature" is considered to be a
command line option. E.g. does "merge" command have the "edit" feature
translates to does git-merge support the '--edit' command line option.

To figure this out, _cmd_has_feature() parses through the "OPTIONS"
section of the man page of the git command.

Signed-off-by: Markus Lehtonen <markus.lehtonen@linux.intel.com>

2 files changed, 59 insertions, 0 deletions

diff --git a/gbp/git/repository.py b/gbp/git/repository.py
index 4c087a89..e31584c8 100644
--- a/gbp/git/repository.py
+++ b/gbp/git/repository.py
@@ -18,6 +18,7 @@
 
 import subprocess
 import os.path
+import re
 from collections import defaultdict
 
 import gbp.log as log
@@ -163,6 +164,39 @@ class GitRepository(object):
             raise GitRepositoryError("Error running git %s: %s" %
                                      (command, excobj))
 
+    def _cmd_has_feature(self, command, feature):
+        """
+        Check if the git command has certain feature enabled.
+
+        @param command: git command
+        @type command: C{str}
+        @param feature: feature / command option to check
+        @type feature: C{str}
+        @return: True if feature is supported
+        @rtype: C{bool}
+        """
+        args = GitArgs(command, '-m')
+        help, foo, ret = self._git_inout('help', args.args)
+        if ret:
+            raise GitRepositoryError("Invalid git command: %s" % command)
+
+        # Parse git command man page
+        section_re = re.compile(r'^(?P<section>[A-Z].*)')
+        option_re = re.compile(r'--?(?P<name>[a-zA-Z\-]+).*')
+        man_section = None
+        for line in help.splitlines():
+            if man_section == "OPTIONS" and line.startswith('       -'):
+                opts = line.split(',')
+                for opt in opts:
+                    match = option_re.match(opt.strip())
+                    if match and match.group('name') == feature:
+                        return True
+            # Check man section
+            match = section_re.match(line)
+            if match:
+                man_section = match.group('section')
+        return False
+
     @property
     def path(self):
         """The absolute path to the repository"""
diff --git a/tests/test_GitRepository.py b/tests/test_GitRepository.py
index aa20e755..f1b50131 100644
--- a/tests/test_GitRepository.py
+++ b/tests/test_GitRepository.py
@@ -753,6 +753,31 @@ def test_get_merge_base():
     GitRepositoryError: Failed to get common ancestor: fatal: Not a valid object name doesnotexist
     """
 
+def test_cmd_has_feature():
+    r"""
+    Methods tested:
+        - L{gbp.git.GitRepository._cmd_has_feature}
+
+    >>> import gbp.git
+    >>> repo = gbp.git.GitRepository(repo_dir)
+    >>> repo._cmd_has_feature("commit", "a")
+    True
+    >>> repo._cmd_has_feature("commit", "reuse-message")
+    True
+    >>> repo._cmd_has_feature("merge", "n")
+    True
+    >>> repo._cmd_has_feature("merge", "stat")
+    True
+    >>> repo._cmd_has_feature("format-patch", "cc")
+    True
+    >>> repo._cmd_has_feature("merge", "foobaroption")
+    False
+    >>> repo._cmd_has_feature("foobarcmd", "foobaroption")
+    Traceback (most recent call last):
+    ...
+    GitRepositoryError: Invalid git command: foobarcmd
+    """
+
 def test_teardown():
     """
     Perform the teardown