Galaxy - make versions list consistent across versions (#72932)

* Galaxy - make versions list consistent across versions

* Fix up unit tests

changelogs/fragments/ansible-galaxy-version-response.yml

@@ -0,0 +1,4 @@
+minor_changes:
+- >-
+  ansible-galaxy - Ensure ``get_collection_versions`` returns an empty list when a collection does
+  not exist for consistency across API versions.

lib/ansible/galaxy/api.py

@@ -751,9 +751,15 @@ class GalaxyAPI:
             server_cache = self._cache.setdefault(get_cache_id(versions_url), {})
             modified_cache = server_cache.setdefault('modified', {})
 
-            modified_date = self.get_collection_metadata(namespace, name).modified_str
-            cached_modified_date = modified_cache.get('%s.%s' % (namespace, name), None)
+            try:
+                modified_date = self.get_collection_metadata(namespace, name).modified_str
+            except GalaxyError as err:
+                if err.http_code != 404:
+                    raise
+                # No collection found, return an empty list to keep things consistent with the various APIs
+                return []
 
+            cached_modified_date = modified_cache.get('%s.%s' % (namespace, name), None)
             if cached_modified_date != modified_date:
                 modified_cache['%s.%s' % (namespace, name)] = modified_date
                 if versions_url_info.path in server_cache:
@@ -763,7 +769,14 @@ class GalaxyAPI:
 
         error_context_msg = 'Error when getting available collection versions for %s.%s from %s (%s)' \
                             % (namespace, name, self.name, self.api_server)
-        data = self._call_galaxy(versions_url, error_context_msg=error_context_msg, cache=True)
+
+        try:
+            data = self._call_galaxy(versions_url, error_context_msg=error_context_msg, cache=True)
+        except GalaxyError as err:
+            if err.http_code != 404:
+                raise
+            # v3 doesn't raise a 404 so we need to mimick the empty response from APIs that do.
+            return []
 
         if 'data' in data:
             # v3 automation-hub is the only known API that uses `data`

lib/ansible/galaxy/collection/__init__.py

@@ -511,29 +511,26 @@ class CollectionRequirement:
         galaxy_meta = None
 
         for api in apis:
-            try:
-                if not (requirement == '*' or requirement.startswith('<') or requirement.startswith('>') or
-                        requirement.startswith('!=')):
-                    # Exact requirement
-                    allow_pre_release = True
+            if not (requirement == '*' or requirement.startswith('<') or requirement.startswith('>') or
+                    requirement.startswith('!=')):
+                # Exact requirement
+                allow_pre_release = True
 
-                    if requirement.startswith('='):
-                        requirement = requirement.lstrip('=')
+                if requirement.startswith('='):
+                    requirement = requirement.lstrip('=')
 
+                try:
                     resp = api.get_collection_version_metadata(namespace, name, requirement)
-
+                except GalaxyError as err:
+                    if err.http_code != 404:
+                        raise
+                    versions = []
+                else:
                     galaxy_meta = resp
                     versions = [resp.version]
-                else:
-                    versions = api.get_collection_versions(namespace, name)
-            except GalaxyError as err:
-                if err.http_code != 404:
-                    raise
-
-                versions = []
+            else:
+                versions = api.get_collection_versions(namespace, name)
 
-            # Automation Hub doesn't return a 404 but an empty version list so we check that to align both AH and
-            # Galaxy when the collection is not available on that server.
             if not versions:
                 display.vvv("Collection '%s' is not available from server %s %s" % (collection, api.name,
                                                                                     api.api_server))

test/units/galaxy/test_collection_install.py

@@ -403,10 +403,9 @@ def test_build_requirement_from_name_second_server(galaxy_server, monkeypatch):
 
     broken_server = copy.copy(galaxy_server)
     broken_server.api_server = 'https://broken.com/'
-    mock_404 = MagicMock()
-    mock_404.side_effect = api.GalaxyError(urllib_error.HTTPError('https://galaxy.server.com', 404, 'msg', {},
-                                                                  StringIO()), "custom msg")
-    monkeypatch.setattr(broken_server, 'get_collection_versions', mock_404)
+    mock_version_list = MagicMock()
+    mock_version_list.return_value = []
+    monkeypatch.setattr(broken_server, 'get_collection_versions', mock_version_list)
 
     actual = collection.CollectionRequirement.from_name('namespace.collection', [broken_server, galaxy_server],
                                                         '>1.0.1', False, True)
@@ -420,8 +419,8 @@ def test_build_requirement_from_name_second_server(galaxy_server, monkeypatch):
     assert actual.latest_version == u'1.0.3'
     assert actual.dependencies == {}
 
-    assert mock_404.call_count == 1
-    assert mock_404.mock_calls[0][1] == ('namespace', 'collection')
+    assert mock_version_list.call_count == 1
+    assert mock_version_list.mock_calls[0][1] == ('namespace', 'collection')
 
     assert mock_get_versions.call_count == 1
     assert mock_get_versions.mock_calls[0][1] == ('namespace', 'collection')
@@ -429,8 +428,7 @@ def test_build_requirement_from_name_second_server(galaxy_server, monkeypatch):
 
 def test_build_requirement_from_name_missing(galaxy_server, monkeypatch):
     mock_open = MagicMock()
-    mock_open.side_effect = api.GalaxyError(urllib_error.HTTPError('https://galaxy.server.com', 404, 'msg', {},
-                                                                   StringIO()), "")
+    mock_open.return_value = []
 
     monkeypatch.setattr(galaxy_server, 'get_collection_versions', mock_open)