clarify that the attribute key (not value) has unexpected type

or is empty 

2 files changed, 27 insertions, 3 deletions

diff --git a/snap/info_snap_yaml.go b/snap/info_snap_yaml.go
index cab8dfdf07..bb5a7c63b7 100644
--- a/snap/info_snap_yaml.go
+++ b/snap/info_snap_yaml.go
@@ -606,7 +606,7 @@ func convertToSlotOrPlugData(plugOrSlot, name string, data interface{}) (iface,
	for keyData, valueData := range data.(map[interface{}]interface{}) {
	key, ok := keyData.(string)
	if !ok {
-	err := fmt.Errorf("%s %q has attribute that is not a string (found %T)",
+	err := fmt.Errorf("%s %q has attribute key that is not a string (found %T)",
	plugOrSlot, name, keyData)
	return "", "", nil, err
	}
@@ -615,6 +615,8 @@ func convertToSlotOrPlugData(plugOrSlot, name string, data interface{}) (iface,
	return "", "", nil, err
	}
	switch key {
+	case "":
+	return "", "", nil, fmt.Errorf("%s %q has an empty attribute key", plugOrSlot, name)
	case "interface":
	value, ok := valueData.(string)
	if !ok {
diff --git a/snap/info_snap_yaml_test.go b/snap/info_snap_yaml_test.go
index f8f8570186..a9cfd0557d 100644
--- a/snap/info_snap_yaml_test.go
+++ b/snap/info_snap_yaml_test.go
@@ -441,7 +441,18 @@ plugs:
 net:
 1: ok
 `))
-	c.Assert(err, ErrorMatches, `plug "net" has attribute that is not a string \(found int\)`)
+	c.Assert(err, ErrorMatches, `plug "net" has attribute key that is not a string \(found int\)`)
+}
+
+func (s *YamlSuite) TestUnmarshalCorruptedPlugWithEmptyAttributeKey(c *C) {
+	// NOTE: yaml content cannot use tabs, indent the section with spaces.
+	_, err := snap.InfoFromSnapYaml([]byte(`
+name: snap
+plugs:
+ net:
+ "": ok
+`))
+	c.Assert(err, ErrorMatches, `plug "net" has an empty attribute key`)
 }
 
 func (s *YamlSuite) TestUnmarshalCorruptedPlugWithUnexpectedType(c *C) {
@@ -854,7 +865,18 @@ slots:
 net:
 1: ok
 `))
-	c.Assert(err, ErrorMatches, `slot "net" has attribute that is not a string \(found int\)`)
+	c.Assert(err, ErrorMatches, `slot "net" has attribute key that is not a string \(found int\)`)
+}
+
+func (s *YamlSuite) TestUnmarshalCorruptedSlotWithEmptyAttributeKey(c *C) {
+	// NOTE: yaml content cannot use tabs, indent the section with spaces.
+	_, err := snap.InfoFromSnapYaml([]byte(`
+name: snap
+slots:
+ net:
+ "": ok
+`))
+	c.Assert(err, ErrorMatches, `slot "net" has an empty attribute key`)
 }
 
 func (s *YamlSuite) TestUnmarshalCorruptedSlotWithUnexpectedType(c *C) {