From aa8fceae7eccbd7d2506edade618fdf3b705006c Mon Sep 17 00:00:00 2001
From: Omer E <33223663+tcdsv@users.noreply.github.com>
Date: Wed, 24 Apr 2024 12:49:27 +0300
Subject: [PATCH] flatten-allof fix circular additionalProperties overflow
 (#529)

---
 flatten/allof/merge_allof.go                  |  4 +-
 flatten/allof/merge_allof_spec_test.go        | 45 +++++++++++++++++++
 .../testdata/circular_additional_props1.yaml  | 14 ++++++
 .../testdata/circular_additional_props2.yaml  | 19 ++++++++
 .../testdata/circular_additional_props3.yaml  | 17 +++++++
 5 files changed, 98 insertions(+), 1 deletion(-)
 create mode 100644 flatten/allof/testdata/circular_additional_props1.yaml
 create mode 100644 flatten/allof/testdata/circular_additional_props2.yaml
 create mode 100644 flatten/allof/testdata/circular_additional_props3.yaml

diff --git a/flatten/allof/merge_allof.go b/flatten/allof/merge_allof.go
index 0bdac0fe..1ff2c311 100644
--- a/flatten/allof/merge_allof.go
+++ b/flatten/allof/merge_allof.go
@@ -580,7 +580,9 @@ func resolveNonFalseAdditionalProps(state *state, schema *openapi3.Schema, colle
 	}
 
 	var schemaRef *openapi3.SchemaRef
-	if len(additionalSchemas) > 0 {
+	if len(additionalSchemas) == 1 {
+		schemaRef = additionalSchemas[0]
+	} else if len(additionalSchemas) > 1 {
 		result := openapi3.NewSchemaRef("", openapi3.NewSchema())
 		err := flattenSchemas(state, result, additionalSchemas)
 		if err != nil {
diff --git a/flatten/allof/merge_allof_spec_test.go b/flatten/allof/merge_allof_spec_test.go
index 48fff4f7..507e96ff 100644
--- a/flatten/allof/merge_allof_spec_test.go
+++ b/flatten/allof/merge_allof_spec_test.go
@@ -26,3 +26,48 @@ func Test_MergeSpecInvalid(t *testing.T) {
 	_, err := load.NewSpecInfo(openapi3.NewLoader(), load.NewSource("../../data/allof/invalid.yaml"), load.WithFlattenAllOf())
 	require.EqualError(t, err, "failed to flatten allOf in \"../../data/allof/invalid.yaml\": unable to resolve Type conflict: all Type values must be identical")
 }
+
+func TestMergeSpec_CircularAdditionalPropsWithoutAllOf(t *testing.T) {
+	spec, err := load.NewSpecInfo(openapi3.NewLoader(), load.NewSource("testdata/circular_additional_props1.yaml"), load.WithFlattenAllOf())
+	require.NoError(t, err)
+
+	merged := spec.Spec
+	require.Equal(t, "object", merged.Components.Schemas["BaseSchema"].Value.Properties["prop1"].Value.Type)
+	require.NotNil(t, merged.Components.Schemas["BaseSchema"].Value.Properties["prop1"].Value.AdditionalProperties.Schema)
+	require.NotNil(t, merged.Components.Schemas["BaseSchema"].Value.Properties["prop1"].Value.AdditionalProperties.Schema.Value)
+
+	baseSchema := merged.Components.Schemas["BaseSchema"].Value
+	referencedAdditionalPropSchema := merged.Components.Schemas["BaseSchema"].Value.Properties["prop1"].Value.AdditionalProperties.Schema.Value
+	require.Equal(t, baseSchema, referencedAdditionalPropSchema)
+}
+
+func TestMergeSpec_MergeCircularAdditionalPropsWithAllOf(t *testing.T) {
+	spec, err := load.NewSpecInfo(openapi3.NewLoader(), load.NewSource("testdata/circular_additional_props2.yaml"), load.WithFlattenAllOf())
+	require.NoError(t, err)
+
+	merged := spec.Spec
+	require.Nil(t, merged.Components.Schemas["BaseSchema"].Value.AllOf)
+	require.Equal(t, "string", merged.Components.Schemas["BaseSchema"].Value.Properties["fixedProperty"].Value.Type)
+	require.Equal(t, "object", merged.Components.Schemas["BaseSchema"].Value.Properties["prop1"].Value.Type)
+	require.NotNil(t, merged.Components.Schemas["BaseSchema"].Value.Properties["prop1"].Value.AdditionalProperties.Schema)
+	require.NotNil(t, merged.Components.Schemas["BaseSchema"].Value.Properties["prop1"].Value.AdditionalProperties.Schema.Value)
+
+	baseSchema := merged.Components.Schemas["BaseSchema"].Value
+	referencedAdditionalPropSchema := merged.Components.Schemas["BaseSchema"].Value.Properties["prop1"].Value.AdditionalProperties.Schema.Value
+	require.Equal(t, baseSchema, referencedAdditionalPropSchema)
+}
+
+func TestMergeSpec_MergeCircularAdditionalPropsNestedWithinAllOf(t *testing.T) {
+	spec, err := load.NewSpecInfo(openapi3.NewLoader(), load.NewSource("testdata/circular_additional_props3.yaml"), load.WithFlattenAllOf())
+	require.NoError(t, err)
+
+	merged := spec.Spec
+	require.Nil(t, merged.Components.Schemas["BaseSchema"].Value.AllOf)
+	require.Equal(t, "object", merged.Components.Schemas["BaseSchema"].Value.Properties["prop1"].Value.Type)
+	require.NotNil(t, merged.Components.Schemas["BaseSchema"].Value.Properties["prop1"].Value.AdditionalProperties.Schema)
+	require.NotNil(t, merged.Components.Schemas["BaseSchema"].Value.Properties["prop1"].Value.AdditionalProperties.Schema.Value)
+
+	baseSchemaReferencedAdditionalPropSchema := merged.Components.Schemas["BaseSchema"].Value.Properties["prop1"].Value.AdditionalProperties.Schema.Value
+	NestedSelfReferentialSchema := merged.Components.Schemas["NestedSelfReferentialSchema"].Value
+	require.Equal(t, baseSchemaReferencedAdditionalPropSchema, NestedSelfReferentialSchema)
+}
diff --git a/flatten/allof/testdata/circular_additional_props1.yaml b/flatten/allof/testdata/circular_additional_props1.yaml
new file mode 100644
index 00000000..e51a38f4
--- /dev/null
+++ b/flatten/allof/testdata/circular_additional_props1.yaml
@@ -0,0 +1,14 @@
+openapi: 3.0.0
+info:
+  title: Circular AdditionalProperties
+  version: 1.0.0
+paths: {}
+components:
+  schemas:
+    BaseSchema:
+      type: object
+      properties:
+        prop1:
+          type: object
+          additionalProperties:
+            $ref: '#/components/schemas/BaseSchema'
\ No newline at end of file
diff --git a/flatten/allof/testdata/circular_additional_props2.yaml b/flatten/allof/testdata/circular_additional_props2.yaml
new file mode 100644
index 00000000..9fe3da1c
--- /dev/null
+++ b/flatten/allof/testdata/circular_additional_props2.yaml
@@ -0,0 +1,19 @@
+openapi: 3.0.0
+info:
+  title: Circular AdditionalProperties
+  version: 1.0.0
+paths: {}
+components:
+  schemas:
+    BaseSchema:
+      type: object
+      allOf:
+        - type: object
+          properties:
+            fixedProperty:
+              type: string
+      properties:
+        prop1:
+          type: object
+          additionalProperties:
+            $ref: '#/components/schemas/BaseSchema'
\ No newline at end of file
diff --git a/flatten/allof/testdata/circular_additional_props3.yaml b/flatten/allof/testdata/circular_additional_props3.yaml
new file mode 100644
index 00000000..4bc49fd8
--- /dev/null
+++ b/flatten/allof/testdata/circular_additional_props3.yaml
@@ -0,0 +1,17 @@
+openapi: 3.0.0
+info:
+  title: Self-Referential allOf Schema API
+  version: 1.0.0
+paths: {}
+components:
+  schemas:
+    BaseSchema:
+      allOf:
+        - $ref: '#/components/schemas/NestedSelfReferentialSchema'
+    NestedSelfReferentialSchema:
+      type: object
+      properties:
+        prop1:
+          type: object
+          additionalProperties:
+            $ref: '#/components/schemas/NestedSelfReferentialSchema'