More specific exceptions when a project.conf is missing.

Since we want to react and start an interactive session when the
project.conf is missing, we need a more specific error to catch.

4 files changed, 18 insertions, 7 deletions

diff --git a/buildstream/_exceptions.py b/buildstream/_exceptions.py
index fc44f4989..d8687104f 100644
--- a/buildstream/_exceptions.py
+++ b/buildstream/_exceptions.py
@@ -182,14 +182,20 @@ class LoadErrorReason(Enum):
     # Conflicting junctions in subprojects
     CONFLICTING_JUNCTION = 12
 
+    # Failure to load a project from a specified junction
+    INVALID_JUNCTION = 13
+
     # Subproject needs to be fetched
-    SUBPROJECT_FETCH_NEEDED = 13
+    SUBPROJECT_FETCH_NEEDED = 14
 
     # Subproject has no ref
-    SUBPROJECT_INCONSISTENT = 14
+    SUBPROJECT_INCONSISTENT = 15
 
     # An invalid symbol name was encountered
-    INVALID_SYMBOL_NAME = 15
+    INVALID_SYMBOL_NAME = 16
+
+    # A project.conf file was missing
+    MISSING_PROJECT_CONF = 17
 
 
 # LoadError
diff --git a/buildstream/_loader.py b/buildstream/_loader.py
index 44f38e3f1..2fc7d8f0c 100644
--- a/buildstream/_loader.py
+++ b/buildstream/_loader.py
@@ -384,8 +384,8 @@ class Loader():
         try:
             project = Project(project_dir, self.context, junction=element)
         except LoadError as e:
-            if e.reason == LoadErrorReason.MISSING_FILE:
-                raise LoadError(reason=e.reason,
+            if e.reason == LoadErrorReason.MISSING_PROJECT_CONF:
+                raise LoadError(reason=LoadErrorReason.INVALID_JUNCTION,
                                 message="Could not find the project.conf file for {}. "
                                         "Expecting a project at path '{}' within {}"
                                 .format(element, element.path or '.', source)) from e
diff --git a/buildstream/_project.py b/buildstream/_project.py
index c7f535e23..e71bdf0f1 100644
--- a/buildstream/_project.py
+++ b/buildstream/_project.py
@@ -214,7 +214,12 @@ class Project():
         config = _yaml.load(_site.default_project_config)
 
         # Load project local config and override the builtin
-        project_conf = _yaml.load(projectfile)
+        try:
+            project_conf = _yaml.load(projectfile)
+        except LoadError as e:
+            # Raise a more specific error here
+            raise LoadError(LoadErrorReason.MISSING_PROJECT_CONF, str(e))
+
         _yaml.composite(config, project_conf)
 
         # Element and Source  type configurations will be composited later onto
diff --git a/tests/format/project.py b/tests/format/project.py
index cfa02bd52..b8e411351 100644
--- a/tests/format/project.py
+++ b/tests/format/project.py
@@ -16,7 +16,7 @@ DATA_DIR = os.path.join(
 def test_missing_project_conf(cli, datafiles):
     project = os.path.join(datafiles.dirname, datafiles.basename)
     result = cli.run(project=project, args=['workspace', 'list'])
-    result.assert_main_error(ErrorDomain.LOAD, LoadErrorReason.MISSING_FILE)
+    result.assert_main_error(ErrorDomain.LOAD, LoadErrorReason.MISSING_PROJECT_CONF)
 
 
 @pytest.mark.datafiles(os.path.join(DATA_DIR))