Issue 430 (#434)

flatten/merge_allof.go

@@ -90,11 +90,22 @@ func Merge(schema openapi3.SchemaRef) (*openapi3.Schema, error) {
 		if err != nil {
 			return nil, err
 		}
+		pruneFields(schema)
 	}
 
 	return result.Value, nil
 }
 
+// remove fields while maintaining an equivalent schema.
+func pruneFields(schema *openapi3.SchemaRef) {
+	if len(schema.Value.OneOf) == 1 && schema.Value.OneOf[0].Value == schema.Value {
+		schema.Value.OneOf = nil
+	}
+	if len(schema.Value.AnyOf) == 1 && schema.Value.AnyOf[0].Value == schema.Value {
+		schema.Value.AnyOf = nil
+	}
+}
+
 func mergeCircularAllOf(state *state, baseSchemaRef *openapi3.SchemaRef) error {
 	schemaRefs := openapi3.SchemaRefs{baseSchemaRef}
 	schemaRefs = append(schemaRefs, baseSchemaRef.Value.AllOf...)
@@ -630,8 +641,20 @@ func resolveEnum(values [][]interface{}) ([]interface{}, error) {
 }
 
 func resolvePattern(values []string) string {
+	patterns := []string{}
+	for _, v := range values {
+		if len(v) > 0 {
+			patterns = append(patterns, v)
+		}
+	}
+	if len(patterns) == 0 {
+		return ""
+	}
+	if len(patterns) == 1 {
+		return patterns[0]
+	}
 	var pattern strings.Builder
-	for _, p := range values {
+	for _, p := range patterns {
 		if len(p) > 0 {
 			if !isPatternResolved(p) {
 				pattern.WriteString(fmt.Sprintf("(?=%s)", p))

flatten/merge_allof_test.go

@@ -1715,8 +1715,30 @@ func TestMerge_AdditionalProperties_True(t *testing.T) {
 }
 
 func TestMergeAllOf_Pattern(t *testing.T) {
-
 	merged, err := flatten.Merge(
+		openapi3.SchemaRef{
+			Value: &openapi3.Schema{
+				Pattern: "abc",
+			}})
+	require.NoError(t, err)
+	require.Equal(t, "abc", merged.Pattern)
+
+	merged, err = flatten.Merge(
+		openapi3.SchemaRef{
+			Value: &openapi3.Schema{
+				AllOf: openapi3.SchemaRefs{
+					&openapi3.SchemaRef{
+						Value: &openapi3.Schema{
+							Type:    "object",
+							Pattern: "abc",
+						},
+					},
+				},
+			}})
+	require.NoError(t, err)
+	require.Equal(t, "abc", merged.Pattern)
+
+	merged, err = flatten.Merge(
 		openapi3.SchemaRef{
 			Value: &openapi3.Schema{
 				AllOf: openapi3.SchemaRefs{
@@ -1778,14 +1800,48 @@ func TestMerge_CircularAllOf(t *testing.T) {
 	merged, err := flatten.Merge(*doc.Components.Schemas["AWSEnvironmentSettings"])
 	require.NoError(t, err)
 	require.Empty(t, merged.AllOf)
-
-	require.Equal(t, "#/components/schemas/AWSEnvironmentSettings", merged.OneOf[0].Ref)
-	require.Equal(t, &merged, &merged.OneOf[0].Value)
+	require.Empty(t, merged.OneOf)
 
 	require.Equal(t, "string", merged.Properties["serviceEndpoints"].Value.Type)
 	require.Equal(t, "string", merged.Properties["region"].Value.Type)
 }
 
+// A single OneOf field is pruned if it references it's parent schema
+func TestMerge_OneOfIsPruned(t *testing.T) {
+	doc := loadSpec(t, "testdata/circular2.yaml")
+	merged, err := flatten.Merge(*doc.Components.Schemas["OneOf_Is_Pruned_B"])
+	require.NoError(t, err)
+	require.Empty(t, merged.AllOf)
+	require.Empty(t, merged.OneOf)
+}
+
+// A single OneOf field is not pruned if it does not reference it's parent schema
+func TestMerge_OneOfIsNotPruned(t *testing.T) {
+	doc := loadSpec(t, "testdata/circular2.yaml")
+	merged, err := flatten.Merge(*doc.Components.Schemas["OneOf_Is_Not_Pruned_B"])
+	require.NoError(t, err)
+	require.Empty(t, merged.AllOf)
+	require.NotEmpty(t, merged.OneOf)
+}
+
+// A single AnyOf field is pruned if it references it's parent schema
+func TestMerge_AnyOfIsPruned(t *testing.T) {
+	doc := loadSpec(t, "testdata/circular2.yaml")
+	merged, err := flatten.Merge(*doc.Components.Schemas["AnyOf_Is_Pruned_B"])
+	require.NoError(t, err)
+	require.Empty(t, merged.AllOf)
+	require.Empty(t, merged.AnyOf)
+}
+
+// A single AnyOf field is not pruned if it does not reference it's parent schema
+func TestMerge_AnyOfIsNotPruned(t *testing.T) {
+	doc := loadSpec(t, "testdata/circular2.yaml")
+	merged, err := flatten.Merge(*doc.Components.Schemas["AnyOf_Is_Not_Pruned_B"])
+	require.NoError(t, err)
+	require.Empty(t, merged.AllOf)
+	require.NotEmpty(t, merged.AnyOf)
+}
+
 func loadSpec(t *testing.T, path string) *openapi3.T {
 	ctx := context.Background()
 	sl := openapi3.NewLoader()

flatten/testdata/circular2.yaml

@@ -0,0 +1,58 @@
+openapi: 3.0.0
+info:
+  title: Circular Reference Example
+  version: 1.0.0
+paths:
+  /sample:
+    put:
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/OneOf_Is_Pruned_A'
+      responses:
+        '200':
+          description: Ok
+
+components:
+  schemas:
+    OneOf_Is_Pruned_A:
+      type: object
+      oneOf: 
+        - $ref: '#/components/schemas/OneOf_Is_Pruned_B'
+
+    OneOf_Is_Pruned_B:
+      type: object
+      allOf:
+        - $ref: '#/components/schemas/OneOf_Is_Pruned_A'
+
+    OneOf_Is_Not_Pruned_A:
+      type: object
+      oneOf: 
+        - type: object
+
+    OneOf_Is_Not_Pruned_B:
+      type: object
+      allOf:
+        - $ref: '#/components/schemas/OneOf_Is_Not_Pruned_A'  
+
+    AnyOf_Is_Pruned_A:
+      type: object
+      anyOf: 
+        - $ref: '#/components/schemas/AnyOf_Is_Pruned_B'
+
+    AnyOf_Is_Pruned_B:
+      type: object
+      allOf:
+        - $ref: '#/components/schemas/AnyOf_Is_Pruned_A'
+
+    AnyOf_Is_Not_Pruned_A:
+      type: object
+      anyOf: 
+        - type: object
+
+    AnyOf_Is_Not_Pruned_B:
+      type: object
+      allOf:
+        - $ref: '#/components/schemas/AnyOf_Is_Not_Pruned_A'