openapi3: introduce LoadFromIoReader (#906)

* add loader from io.Reader

* fix docs

* fix whitespace

* fix loader := NewLoader()

.github/docs/openapi3.txt

@@ -586,6 +586,9 @@ func (loader *Loader) LoadFromDataWithPath(data []byte, location *url.URL) (*T,
 func (loader *Loader) LoadFromFile(location string) (*T, error)
     LoadFromFile loads a spec from a local file path
 
+func (loader *Loader) LoadFromIoReader(reader io.Reader) (*T, error)
+    LoadFromStdin loads a spec from io.Reader
+
 func (loader *Loader) LoadFromStdin() (*T, error)
     LoadFromStdin loads a spec from stdin
 

openapi3/loader.go

@@ -126,9 +126,18 @@ func (loader *Loader) readURL(location *url.URL) ([]byte, error) {
 
 // LoadFromStdin loads a spec from stdin
 func (loader *Loader) LoadFromStdin() (*T, error) {
-	data, err := io.ReadAll(os.Stdin)
+	return loader.LoadFromIoReader(os.Stdin)
+}
+
+// LoadFromStdin loads a spec from io.Reader
+func (loader *Loader) LoadFromIoReader(reader io.Reader) (*T, error) {
+	if reader == nil {
+		return nil, fmt.Errorf("invalid reader: %v", reader)
+	}
+
+	data, err := io.ReadAll(reader)
 	if err != nil {
-		return nil, fmt.Errorf("read from stdin: %w", err)
+		return nil, err
 	}
 	return loader.LoadFromData(data)
 }

openapi3/loader_test.go

@@ -1,6 +1,7 @@
 package openapi3
 
 import (
+	"bytes"
 	"fmt"
 	"net"
 	"net/http"
@@ -621,3 +622,53 @@ servers:
 		})
 	}
 }
+
+func TestReadFromIoReader(t *testing.T) {
+	buffer := bytes.NewReader([]byte(`openapi: 3.0.0
+info:
+  title: An API
+  version: v1
+components:
+  schemas:
+    NewItem:
+      required: [name]
+      properties:
+        name: {type: string}
+        tag: {type: string}
+    ErrorModel:
+      type: object
+      required: [code, message]
+      properties:
+        code: {type: integer}
+        message: {type: string}
+paths:
+  /items:
+    put:
+      description: ''
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/NewItem'
+      responses:
+        default: &defaultResponse # a YAML ref
+          description: unexpected error
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorModel'`))
+
+	loader := NewLoader()
+	doc, err := loader.LoadFromIoReader(buffer)
+	require.NoError(t, err)
+
+	err = doc.Validate(loader.Context)
+	require.NoError(t, err)
+}
+
+func TestReadFromIoReader_Nil(t *testing.T) {
+	loader := NewLoader()
+	_, err := loader.LoadFromIoReader(nil)
+	require.EqualError(t, err, "invalid reader: <nil>")
+}