openapi3: allow YAML-marshaling invalid specs (getkin#977)

* openapi3: allow YAML-marshaling invalid specs

Signed-off-by: Pierre Fenoll <pierrefenoll@gmail.com>

* fixes

Signed-off-by: Pierre Fenoll <pierrefenoll@gmail.com>

---------

Signed-off-by: Pierre Fenoll <pierrefenoll@gmail.com>

.github/docs/openapi3.txt

@@ -645,7 +645,7 @@ type Info struct {
 func (info Info) MarshalJSON() ([]byte, error)
     MarshalJSON returns the JSON encoding of Info.
 
-func (info Info) MarshalYAML() (any, error)
+func (info *Info) MarshalYAML() (any, error)
     MarshalYAML returns the YAML encoding of Info.
 
 func (info *Info) UnmarshalJSON(data []byte) error

maps.sh

@@ -155,9 +155,16 @@ EOF
 
 
 maplike_UnMarsh() {
+	if [[ "$type" != '*'* ]]; then
+		echo "TODO: impl non-pointer receiver YAML Marshaler"
+		exit 2
+	fi
 	cat <<EOF >>"$maplike"
 // MarshalYAML returns the YAML encoding of ${type#'*'}.
 func (${name} ${type}) MarshalYAML() (any, error) {
+	if ${name} == nil {
+		return nil, nil
+	}
 	m := make(map[string]any, ${name}.Len()+len(${name}.Extensions))
 	for k, v := range ${name}.Extensions {
 		m[k] = v

openapi3/info.go

@@ -29,7 +29,10 @@ func (info Info) MarshalJSON() ([]byte, error) {
 }
 
 // MarshalYAML returns the YAML encoding of Info.
-func (info Info) MarshalYAML() (any, error) {
+func (info *Info) MarshalYAML() (any, error) {
+	if info == nil {
+		return nil, nil
+	}
 	m := make(map[string]any, 6+len(info.Extensions))
 	for k, v := range info.Extensions {
 		m[k] = v

openapi3/issue972_test.go

@@ -0,0 +1,66 @@
+package openapi3
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"gopkg.in/yaml.v3"
+)
+
+func TestIssue972(t *testing.T) {
+	type testcase struct {
+		spec                    string
+		validationErrorContains string
+	}
+
+	base := `
+openapi: 3.0.2
+paths: {}
+components: {}
+`
+
+	for _, tc := range []testcase{{
+		spec:                    base,
+		validationErrorContains: "invalid info: must be an object",
+	}, {
+		spec: base + `
+info:
+  title: "Hello World REST APIs"
+  version: "1.0"
+`,
+	}, {
+		spec: base + `
+info: null
+`,
+		validationErrorContains: "invalid info: must be an object",
+	}, {
+		spec: base + `
+info: {}
+`,
+		validationErrorContains: "invalid info: value of version must be a non-empty string",
+	}, {
+		spec: base + `
+info:
+  title: "Hello World REST APIs"
+`,
+		validationErrorContains: "invalid info: value of version must be a non-empty string",
+	}} {
+		t.Logf("spec: %s", tc.spec)
+
+		loader := &Loader{}
+		doc, err := loader.LoadFromData([]byte(tc.spec))
+		assert.NoError(t, err)
+		assert.NotNil(t, doc)
+
+		err = doc.Validate(loader.Context)
+		if e := tc.validationErrorContains; e != "" {
+			assert.ErrorContains(t, err, e)
+		} else {
+			assert.NoError(t, err)
+		}
+
+		txt, err := yaml.Marshal(doc)
+		assert.NoError(t, err)
+		assert.NotEmpty(t, txt)
+	}
+}

openapi3/loader.go

@@ -1140,8 +1140,7 @@ func (loader *Loader) resolvePathItemRef(doc *T, pathItem *PathItem, documentPat
 			*pathItem = p
 		} else {
 			var resolved PathItem
-			doc, documentPath, err = loader.resolveComponent(doc, ref, documentPath, &resolved)
-			if err != nil {
+			if doc, documentPath, err = loader.resolveComponent(doc, ref, documentPath, &resolved); err != nil {
 				if err == errMUSTPathItem {
 					return nil
 				}

openapi3/maplike.go

@@ -78,6 +78,9 @@ func (responses Responses) JSONLookup(token string) (any, error) {
 
 // MarshalYAML returns the YAML encoding of Responses.
 func (responses *Responses) MarshalYAML() (any, error) {
+	if responses == nil {
+		return nil, nil
+	}
 	m := make(map[string]any, responses.Len()+len(responses.Extensions))
 	for k, v := range responses.Extensions {
 		m[k] = v
@@ -206,6 +209,9 @@ func (callback Callback) JSONLookup(token string) (any, error) {
 
 // MarshalYAML returns the YAML encoding of Callback.
 func (callback *Callback) MarshalYAML() (any, error) {
+	if callback == nil {
+		return nil, nil
+	}
 	m := make(map[string]any, callback.Len()+len(callback.Extensions))
 	for k, v := range callback.Extensions {
 		m[k] = v
@@ -334,6 +340,9 @@ func (paths Paths) JSONLookup(token string) (any, error) {
 
 // MarshalYAML returns the YAML encoding of Paths.
 func (paths *Paths) MarshalYAML() (any, error) {
+	if paths == nil {
+		return nil, nil
+	}
 	m := make(map[string]any, paths.Len()+len(paths.Extensions))
 	for k, v := range paths.Extensions {
 		m[k] = v

openapi3/openapi3.go

@@ -66,6 +66,9 @@ func (doc *T) MarshalJSON() ([]byte, error) {
 
 // MarshalYAML returns the YAML encoding of T.
 func (doc *T) MarshalYAML() (any, error) {
+	if doc == nil {
+		return nil, nil
+	}
 	m := make(map[string]any, 4+len(doc.Extensions))
 	for k, v := range doc.Extensions {
 		m[k] = v

openapi3/schema_formats_test.go

@@ -169,13 +169,13 @@ func TestNumberFormats(t *testing.T) {
 	}
 	DefineNumberFormatValidator("lessThan10", NewCallbackValidator(func(value float64) error {
 		if value >= 10 {
-			return fmt.Errorf("not less than 10")
+			return errors.New("not less than 10")
 		}
 		return nil
 	}))
 	DefineIntegerFormatValidator("odd", NewCallbackValidator(func(value int64) error {
 		if value%2 == 0 {
-			return fmt.Errorf("not odd")
+			return errors.New("not odd")
 		}
 		return nil
 	}))