Fix go1.17 test error (gin-gonic#2856)

(cherry picked from commit e4c026e)

context_1.16_test.go

@@ -0,0 +1,31 @@
+// Copyright 2021 Gin Core Team.  All rights reserved.
+// Use of this source code is governed by a MIT style
+// license that can be found in the LICENSE file.
+
+//go:build !go1.17
+// +build !go1.17
+
+package gin
+
+import (
+	"bytes"
+	"mime/multipart"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestContextFormFileFailed16(t *testing.T) {
+	buf := new(bytes.Buffer)
+	mw := multipart.NewWriter(buf)
+	mw.Close()
+	c, _ := CreateTestContext(httptest.NewRecorder())
+	c.Request, _ = http.NewRequest("POST", "/", nil)
+	c.Request.Header.Set("Content-Type", mw.FormDataContentType())
+	c.engine.MaxMultipartMemory = 8 << 20
+	f, err := c.FormFile("file")
+	assert.Error(t, err)
+	assert.Nil(t, f)
+}

context_1.17_test.go

@@ -0,0 +1,33 @@
+// Copyright 2021 Gin Core Team.  All rights reserved.
+// Use of this source code is governed by a MIT style
+// license that can be found in the LICENSE file.
+
+//go:build go1.17
+// +build go1.17
+
+package gin
+
+import (
+	"bytes"
+	"mime/multipart"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestContextFormFileFailed17(t *testing.T) {
+	buf := new(bytes.Buffer)
+	mw := multipart.NewWriter(buf)
+	mw.Close()
+	c, _ := CreateTestContext(httptest.NewRecorder())
+	c.Request, _ = http.NewRequest("POST", "/", nil)
+	c.Request.Header.Set("Content-Type", mw.FormDataContentType())
+	c.engine.MaxMultipartMemory = 8 << 20
+	assert.Panics(t, func() {
+		f, err := c.FormFile("file")
+		assert.Error(t, err)
+		assert.Nil(t, f)
+	})
+}

context_test.go

@@ -87,19 +87,6 @@ func TestContextFormFile(t *testing.T) {
 	assert.NoError(t, c.SaveUploadedFile(f, "test"))
 }
 
-func TestContextFormFileFailed(t *testing.T) {
-	buf := new(bytes.Buffer)
-	mw := multipart.NewWriter(buf)
-	mw.Close()
-	c, _ := CreateTestContext(httptest.NewRecorder())
-	c.Request, _ = http.NewRequest("POST", "/", nil)
-	c.Request.Header.Set("Content-Type", mw.FormDataContentType())
-	c.engine.MaxMultipartMemory = 8 << 20
-	f, err := c.FormFile("file")
-	assert.Error(t, err)
-	assert.Nil(t, f)
-}
-
 func TestContextMultipartForm(t *testing.T) {
 	buf := new(bytes.Buffer)
 	mw := multipart.NewWriter(buf)