fixed json unmarshal for BoolOrSchema

According to the json draft 4 (or later) spec, empty schema is
equivalent to true.

* checked with the OP's test case (spec expansion)
* added unit test
* fixes go-openapi#148

Signed-off-by: Frederic BIDON <[email protected]>

expander_test.go

@@ -42,6 +42,37 @@ var (
 	specs               = filepath.Join("fixtures", "specs")
 )
 
+func TestExpand_Issue148(t *testing.T) {
+	fp := filepath.Join("fixtures", "bugs", "schema-148.json")
+	b, err := jsonDoc(fp)
+	require.NoError(t, err)
+
+	assertAdditionalProps := func(sp Swagger) func(*testing.T) {
+		return func(t *testing.T) {
+			require.Len(t, sp.Definitions, 2)
+
+			require.Contains(t, sp.Definitions, "empty")
+			empty := sp.Definitions["empty"]
+			require.NotNil(t, empty.AdditionalProperties)
+			require.NotNil(t, empty.AdditionalProperties.Schema)
+			require.True(t, empty.AdditionalProperties.Allows)
+
+			require.Contains(t, sp.Definitions, "false")
+			additionalIsFalse := sp.Definitions["false"]
+			require.NotNil(t, additionalIsFalse.AdditionalProperties)
+			require.Nil(t, additionalIsFalse.AdditionalProperties.Schema)
+			require.False(t, additionalIsFalse.AdditionalProperties.Allows)
+		}
+	}
+
+	var sp Swagger
+	require.NoError(t, json.Unmarshal(b, &sp))
+	t.Run("check additional properties", assertAdditionalProps(sp))
+
+	require.NoError(t, ExpandSpec(&sp, nil))
+	t.Run("check additional properties after expansion", assertAdditionalProps(sp))
+}
+
 func TestExpand_KnownRef(t *testing.T) {
 	// json schema draft 4 meta schema is embedded by default: it resolves without setup
 	schema := RefProperty("http://json-schema.org/draft-04/schema#")

fixtures/bugs/schema-148.json

@@ -0,0 +1,10 @@
+{
+    "definitions": {
+        "empty": {
+            "additionalProperties": {}
+        },
+        "false": {
+            "additionalProperties": false
+        }
+    }
+}

swagger.go

@@ -253,15 +253,15 @@ func (s SchemaOrBool) MarshalJSON() ([]byte, error) {
 // UnmarshalJSON converts this bool or schema object from a JSON structure
 func (s *SchemaOrBool) UnmarshalJSON(data []byte) error {
 	var nw SchemaOrBool
-	if len(data) >= 4 {
+	if len(data) > 0 {
 		if data[0] == '{' {
 			var sch Schema
 			if err := json.Unmarshal(data, &sch); err != nil {
 				return err
 			}
 			nw.Schema = &sch
 		}
-		nw.Allows = !(data[0] == 'f' && data[1] == 'a' && data[2] == 'l' && data[3] == 's' && data[4] == 'e')
+		nw.Allows = !bytes.Equal(data, []byte("false"))
 	}
 	*s = nw
 	return nil