Merge branch 'tristan/yaml-optionally-allow-none' into 'master'

Only optionally allow None values in user provided YAML

Closes #803

See merge request BuildStream/buildstream!999

5 files changed, 18 insertions, 5 deletions

diff --git a/buildstream/_yaml.py b/buildstream/_yaml.py
index 4fe844a80..8d7302b80 100644
--- a/buildstream/_yaml.py
+++ b/buildstream/_yaml.py
@@ -352,6 +352,7 @@ _sentinel = object()
 #    key (str): The key to get a value for in node
 #    indices (list of ints): Optionally decend into lists of lists
 #    default_value: Optionally return this value if the key is not found
+#    allow_none: (bool): Allow None to be a valid value
 #
 # Returns:
 #    The value if found in node, otherwise default_value is returned
@@ -362,7 +363,7 @@ _sentinel = object()
 # Note:
 #    Returned strings are stripped of leading and trailing whitespace
 #
-def node_get(node, expected_type, key, indices=None, default_value=_sentinel):
+def node_get(node, expected_type, key, indices=None, *, default_value=_sentinel, allow_none=False):
     value = node.get(key, default_value)
     provenance = node_get_provenance(node)
     if value is _sentinel:
@@ -377,8 +378,8 @@ def node_get(node, expected_type, key, indices=None, default_value=_sentinel):
             value = value[index]
             path += '[{:d}]'.format(index)
 
-    # We want to allow None as a valid value for any type
-    if value is None:
+    # Optionally allow None as a valid value for any type
+    if value is None and (allow_none or default_value is None):
         return None
 
     if not isinstance(value, expected_type):
diff --git a/buildstream/plugin.py b/buildstream/plugin.py
index 1e8dd4b9f..2f51c8807 100644
--- a/buildstream/plugin.py
+++ b/buildstream/plugin.py
@@ -323,7 +323,7 @@ class Plugin():
         provenance = _yaml.node_get_provenance(node, key=member_name)
         return str(provenance)
 
-    def node_get_member(self, node, expected_type, member_name, default=_yaml._sentinel):
+    def node_get_member(self, node, expected_type, member_name, default=_yaml._sentinel, *, allow_none=False):
         """Fetch the value of a node member, raising an error if the value is
         missing or incorrectly typed.
 
@@ -332,6 +332,7 @@ class Plugin():
            expected_type (type): The expected type of the node member
            member_name (str): The name of the member to fetch
            default (expected_type): A value to return when *member_name* is not specified in *node*
+           allow_none (bool): Allow explicitly set None values in the YAML (*Since: 1.4*)
 
         Returns:
            The value of *member_name* in *node*, otherwise *default*
@@ -352,7 +353,7 @@ class Plugin():
           # Fetch an optional integer
           level = self.node_get_member(node, int, 'level', -1)
         """
-        return _yaml.node_get(node, expected_type, member_name, default_value=default)
+        return _yaml.node_get(node, expected_type, member_name, default_value=default, allow_none=allow_none)
 
     def node_get_project_path(self, node, key, *,
                               check_is_file=False, check_is_dir=False):
diff --git a/tests/format/project.py b/tests/format/project.py
index 46145e578..02e8afb37 100644
--- a/tests/format/project.py
+++ b/tests/format/project.py
@@ -200,3 +200,10 @@ def test_element_path_project_path_contains_symlinks(cli, datafiles, tmpdir):
         f.write("kind: manual\n")
     result = cli.run(project=linked_project, args=['show', 'element.bst'])
     result.assert_success()
+
+
+@pytest.mark.datafiles(os.path.join(DATA_DIR))
+def test_empty_depends(cli, datafiles):
+    project = os.path.join(datafiles.dirname, datafiles.basename, "empty-depends")
+    result = cli.run(project=project, args=['show', 'manual.bst'])
+    result.assert_main_error(ErrorDomain.LOAD, LoadErrorReason.INVALID_DATA)
diff --git a/tests/format/project/empty-depends/manual.bst b/tests/format/project/empty-depends/manual.bst
new file mode 100644
index 000000000..0e168c422
--- /dev/null
+++ b/tests/format/project/empty-depends/manual.bst
@@ -0,0 +1,3 @@
+kind: manual
+
+depends:
diff --git a/tests/format/project/empty-depends/project.conf b/tests/format/project/empty-depends/project.conf
new file mode 100644
index 000000000..b32753625
--- /dev/null
+++ b/tests/format/project/empty-depends/project.conf
@@ -0,0 +1 @@
+name: test