Add api/controller unit tests and mock responses for GetChromeVersion.

BUG=b:1000854
TEST=run_tests

Change-Id: Id0c62fa3bcaf116b3c9ad8319db435944b509e82
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1883679
Reviewed-by: Alex Klein <saklein@chromium.org>
Tested-by: Michael Mortensen <mmortensen@google.com>
Commit-Queue: Michael Mortensen <mmortensen@google.com>
diff --git a/api/controller/packages.py b/api/controller/packages.py
index 772d17e..158fa93 100644
--- a/api/controller/packages.py
+++ b/api/controller/packages.py
@@ -83,7 +83,6 @@
       uprev_response.modified_ebuilds.add().path = path
 
 
-
 @faux.all_empty
 @validate.require('atom')
 @validate.validation_complete
@@ -99,7 +98,13 @@
   output_proto.package_info.CopyFrom(package_info)
 
 
-@faux.all_empty
+def _ChromeVersionResponse(_input_proto, output_proto, _config):
+  """Add a fake chrome version to a successful response."""
+  output_proto.version = '78.0.3900.0'
+
+
+@faux.success(_ChromeVersionResponse)
+@faux.empty_error
 @validate.require('build_target.name')
 @validate.validation_complete
 def GetChromeVersion(input_proto, output_proto, _config):
@@ -108,11 +113,6 @@
   output_proto.version = packages.determine_chrome_version(build_target)
 
 
-def _HasChromePrebuiltSuccess(_input_proto, output_proto, _config):
-  """The mock success case for HasChromePrebuilt."""
-  output_proto.has_prebuilt = True
-
-
 @faux.all_empty
 @validate.require('build_target.name')
 @validate.validation_complete
@@ -137,6 +137,11 @@
   output_proto.full_version = packages.determine_full_version()
 
 
+def _HasChromePrebuiltSuccess(_input_proto, output_proto, _config):
+  """The mock success case for HasChromePrebuilt."""
+  output_proto.has_prebuilt = True
+
+
 @faux.success(_HasChromePrebuiltSuccess)
 @faux.empty_error
 @validate.require('build_target.name')