gclient: Make GetScmName and CreateSCM abstract methods.

Long term plan is to separate GitDependency and CipdDependency,
where most of the current Dependency code is moved to GitDependency,
since it's not relevant to Cipd anyway.

Bug: 839925
Change-Id: Ic238a24fa7add302704934f79004e8a9ca886895
Reviewed-on: https://chromium-review.googlesource.com/1044651
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Reviewed-by: Marc-Antoine Ruel <maruel@chromium.org>

gclient.py

@@ -719,17 +719,10 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
                   self, name, package, cipd_root,
                   self.custom_vars, should_process, use_relative_paths,
                   condition, condition_value))
-      elif dep_type == 'git':
-        url = raw_url.format(**self.get_vars())
-        deps_to_add.append(
-            GitDependency(
-                self, name, raw_url, url, None, None, self.custom_vars, None,
-                deps_file, should_process, use_relative_paths, condition,
-                condition_value))
       else:
         url = raw_url.format(**self.get_vars()) if raw_url else None
         deps_to_add.append(
-            Dependency(
+            GitDependency(
                 self, name, raw_url, url, None, None, self.custom_vars, None,
                 deps_file, should_process, use_relative_paths, condition,
                 condition_value))
@@ -1097,38 +1090,11 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
           print('Skipped missing %s' % cwd, file=sys.stderr)
 
   def GetScmName(self, url):
-    """Get the name of the SCM for the given URL.
-
-    While we currently support both git and cipd as SCM implementations,
-    this currently cannot return 'cipd', regardless of the URL, as CIPD
-    has no canonical URL format. If you want to use CIPD as an SCM, you
-    must currently do so by explicitly using a CipdDependency.
-    """
-    if not url:
-      return None
-    url, _ = gclient_utils.SplitUrlRevision(url)
-    if url.endswith('.git'):
-      return 'git'
-    protocol = url.split('://')[0]
-    if protocol in (
-        'file', 'git', 'git+http', 'git+https', 'http', 'https', 'ssh', 'sso'):
-      return 'git'
-    return None
+    raise NotImplementedError()
 
   def CreateSCM(self, url, root_dir=None, relpath=None, out_fh=None,
                 out_cb=None):
-    SCM_MAP = {
-      'cipd': gclient_scm.CipdWrapper,
-      'git': gclient_scm.GitWrapper,
-    }
-
-    scm_name = self.GetScmName(url)
-    if not scm_name in SCM_MAP:
-      raise gclient_utils.Error('No SCM found for url %s' % url)
-    scm_class = SCM_MAP[scm_name]
-    if not scm_class.BinaryExists():
-      raise gclient_utils.Error('%s command not found' % scm_name)
-    return scm_class(url, root_dir, relpath, out_fh, out_cb, self.print_outbuf)
+    raise NotImplementedError()
 
   def HasGNArgsFile(self):
     return self._gn_args_file is not None
@@ -1399,7 +1365,24 @@ def _detect_host_os():
   return _PLATFORM_MAPPING[sys.platform]
 
 
-class GClient(Dependency):
+class GitDependency(Dependency):
+  """A Dependency object that represents a single git checkout."""
+
+  #override
+  def GetScmName(self, url):
+    """Always 'git'."""
+    del url
+    return 'git'
+
+  #override
+  def CreateSCM(self, url, root_dir=None, relpath=None, out_fh=None,
+                out_cb=None):
+    """Create a Wrapper instance suitable for handling this git dependency."""
+    return gclient_scm.GitWrapper(url, root_dir, relpath, out_fh, out_cb,
+                                  print_outbuf=self.print_outbuf)
+
+
+class GClient(GitDependency):
   """Object that represent a gclient checkout. A tree of Dependency(), one per
   solution or DEPS entry."""
 
@@ -1441,7 +1424,7 @@ solutions = %(solution_list)s
     # Do not change previous behavior. Only solution level and immediate DEPS
     # are processed.
     self._recursion_limit = 2
-    Dependency.__init__(self, None, None, None, None, True, None, None, None,
+    GitDependency.__init__(self, None, None, None, None, True, None, None, None,
                            'unused', True, None, None, True)
     self._options = options
     if options.deps_os:
@@ -1461,7 +1444,7 @@ solutions = %(solution_list)s
     solutions."""
     for dep in self.dependencies:
       if dep.managed and dep.url:
-        scm = self.CreateSCM(
+        scm = dep.CreateSCM(
             dep.url, self.root_dir, dep.name, self.outbuf)
         actual_url = scm.GetActualRemoteURL(self._options)
         if actual_url and not scm.DoesRemoteURLMatch(self._options):
@@ -1533,7 +1516,7 @@ it or fix the checkout.
     deps_to_add = []
     for s in config_dict.get('solutions', []):
       try:
-        deps_to_add.append(Dependency(
+        deps_to_add.append(GitDependency(
             self, s['name'], s['url'], s['url'],
             s.get('managed', True),
             s.get('custom_deps', {}),
@@ -1757,8 +1740,8 @@ it or fix the checkout.
             (not any(path.startswith(entry + '/') for path in entries)) and
             os.path.exists(e_dir)):
           # The entry has been removed from DEPS.
-          scm = self.CreateSCM(
-              prev_url, self.root_dir, entry_fixed, self.outbuf)
+          scm = GitDependency.CreateSCM(
+              self, prev_url, self.root_dir, entry_fixed, self.outbuf)
 
           # Check to see if this directory is now part of a higher-up checkout.
           scm_root = None
@@ -1965,22 +1948,6 @@ it or fix the checkout.
     return self._enforced_cpu
 
 
-class GitDependency(Dependency):
-  """A Dependency object that represents a single git checkout."""
-
-  #override
-  def GetScmName(self, url):
-    """Always 'git'."""
-    del url
-    return 'git'
-
-  #override
-  def CreateSCM(self, url, root_dir=None, relpath=None, out_fh=None,
-                out_cb=None):
-    """Create a Wrapper instance suitable for handling this git dependency."""
-    return gclient_scm.GitWrapper(url, root_dir, relpath, out_fh, out_cb)
-
-
 class CipdDependency(Dependency):
   """A Dependency object that represents a single CIPD package."""
 

tests/gclient_test.py

@@ -61,15 +61,15 @@ class GclientTest(trial_dir.TestCase):
     self.previous_dir = os.getcwd()
     os.chdir(self.root_dir)
     # Manual mocks.
-    self._old_createscm = gclient.Dependency.CreateSCM
-    gclient.Dependency.CreateSCM = self._createscm
+    self._old_createscm = gclient.GitDependency.CreateSCM
+    gclient.GitDependency.CreateSCM = self._createscm
     self._old_sys_stdout = sys.stdout
     sys.stdout = gclient.gclient_utils.MakeFileAutoFlush(sys.stdout)
     sys.stdout = gclient.gclient_utils.MakeFileAnnotated(sys.stdout)
 
   def tearDown(self):
     self.assertEquals([], self._get_processed())
-    gclient.Dependency.CreateSCM = self._old_createscm
+    gclient.GitDependency.CreateSCM = self._old_createscm
     sys.stdout = self._old_sys_stdout
     os.chdir(self.previous_dir)
     super(GclientTest, self).tearDown()