manifest: re-work ManifestProject's fake attributes

Change the url, revision, and clone_depth properties to plain old
attributes, changing url from None to the empty string. This will be
used to make it possible to type annotate Project in a subsequent
commit.

This seems like even more evidence that ManifestProject is not a
Project in a subtyping sense, should not have been treated like one,
and should be removed (#327).

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>

src/west/manifest.py

@@ -744,11 +744,11 @@ class ManifestProject(Project):
 
     Other readable attributes included for Project compatibility:
 
-    - ``url``: always ``None``; the west manifest is not
+    - ``url``: the empty string; the west manifest is not
       version-controlled by west itself, even though 'west init'
       can fetch a manifest repository from a Git remote
     - ``revision``: ``"HEAD"``
-    - ``clone_depth``: ``None``, because ``url`` is
+    - ``clone_depth``: ``None``, because there's no URL
     '''
 
     def __repr__(self):
@@ -769,6 +769,11 @@ def __init__(self, path=None, west_commands=None, topdir=None):
         '''
         self.name = 'manifest'
 
+        # Pretending that this is a Project, even though it's not (#327)
+        self.url = ''
+        self.revision = 'HEAD'
+        self.clone_depth = None
+
         # Path related attributes
         self.topdir = topdir
         self._abspath = None
@@ -804,30 +809,6 @@ def posixpath(self):
             self._posixpath = PurePath(self.abspath).as_posix()
         return self._posixpath
 
-    @property
-    def url(self):
-        return None
-
-    @url.setter
-    def url(self, url):
-        raise ValueError(url)
-
-    @property
-    def revision(self):
-        return 'HEAD'
-
-    @revision.setter
-    def revision(self, revision):
-        raise ValueError(revision)
-
-    @property
-    def clone_depth(self):
-        return None
-
-    @clone_depth.setter
-    def clone_depth(self, clone_depth):
-        raise ValueError(clone_depth)
-
     def as_dict(self):
         '''Return a representation of this object as a dict, as it would be
         parsed from an equivalent YAML manifest.'''

tests/test_manifest.py

@@ -535,7 +535,7 @@ def test_manifest_project():
     assert mp.topdir is None
     assert mp.abspath is None
     assert mp.posixpath is None
-    assert mp.url is None
+    assert mp.url == ''
     assert mp.revision == 'HEAD'
     assert mp.clone_depth is None
 
@@ -555,7 +555,7 @@ def test_manifest_project():
     assert mp.topdir is None
     assert mp.abspath is None
     assert mp.posixpath is None
-    assert mp.url is None
+    assert mp.url == ''
     assert mp.revision == 'HEAD'
     assert mp.clone_depth is None
 
@@ -577,7 +577,7 @@ def test_manifest_project():
     assert PurePath(nodrive(mp.abspath)) == PurePath('/west_top/my-path')
     assert mp.posixpath is not None
     assert mp.west_commands == ['cmds.yml']
-    assert mp.url is None
+    assert mp.url == ''
     assert mp.revision == 'HEAD'
     assert mp.clone_depth is None