From 4a81d5807a59d026cc55998c23460cd385c56b44 Mon Sep 17 00:00:00 2001
From: sh9336 <saurabh25decem2020@gmail.com>
Date: Fri, 9 Jan 2026 17:27:06 +0530
Subject: [PATCH 1/2] Wrap EOF with helpful message for empty JSON request body

---
 binding/json.go               |  5 +++++
 binding/json_external_test.go | 38 +++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+)
 create mode 100644 binding/json_external_test.go

diff --git a/binding/json.go b/binding/json.go
index f4ae921a..8d524a9d 100644
--- a/binding/json.go
+++ b/binding/json.go
@@ -7,6 +7,7 @@ package binding
 import (
 	"bytes"
 	"errors"
+	"fmt"
 	"io"
 	"net/http"
 
@@ -50,7 +51,11 @@ func decodeJSON(r io.Reader, obj any) error {
 		decoder.DisallowUnknownFields()
 	}
 	if err := decoder.Decode(obj); err != nil {
+		if err == io.EOF {
+			return fmt.Errorf("empty request body: %w", err)
+		}
 		return err
 	}
+
 	return validate(obj)
 }
diff --git a/binding/json_external_test.go b/binding/json_external_test.go
new file mode 100644
index 00000000..32660178
--- /dev/null
+++ b/binding/json_external_test.go
@@ -0,0 +1,38 @@
+package binding_test
+
+import (
+	"bytes"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/gin-gonic/gin"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestJSONBindingEmptyBodyReturnsHelpfulError(t *testing.T) {
+	type Req struct {
+		Name string `json:"name" binding:"required"`
+	}
+
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+
+	req, err := http.NewRequest(http.MethodPost, "/", bytes.NewBuffer(nil))
+	assert.NoError(t, err)
+	req.Header.Set("Content-Type", "application/json")
+
+	c.Request = req
+
+	var r Req
+	err = c.ShouldBindJSON(&r)
+
+	assert.Error(t, err)
+
+	// Current behavior returns plain "EOF", which is not helpful.
+	assert.NotEqual(t, "EOF", err.Error(), "error message should not be plain EOF")
+	assert.Contains(t, err.Error(), "empty request body")
+	assert.ErrorIs(t, err, io.EOF)
+
+}

From cd9b91bb2ef67d3b409e8c2465c806a2d68f5178 Mon Sep 17 00:00:00 2001
From: sh9336 <saurabh25decem2020@gmail.com>
Date: Sat, 10 Jan 2026 10:26:46 +0530
Subject: [PATCH 2/2] Fix lint issues: error wrapping, require assertions,
 formatting

---
 binding/json.go               |  3 ++-
 binding/json_external_test.go | 11 ++++++-----
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/binding/json.go b/binding/json.go
index 8d524a9d..047b9910 100644
--- a/binding/json.go
+++ b/binding/json.go
@@ -51,9 +51,10 @@ func decodeJSON(r io.Reader, obj any) error {
 		decoder.DisallowUnknownFields()
 	}
 	if err := decoder.Decode(obj); err != nil {
-		if err == io.EOF {
+		if errors.Is(err, io.EOF) {
 			return fmt.Errorf("empty request body: %w", err)
 		}
+
 		return err
 	}
 
diff --git a/binding/json_external_test.go b/binding/json_external_test.go
index 32660178..dee7b0d0 100644
--- a/binding/json_external_test.go
+++ b/binding/json_external_test.go
@@ -9,6 +9,7 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestJSONBindingEmptyBodyReturnsHelpfulError(t *testing.T) {
@@ -20,7 +21,7 @@ func TestJSONBindingEmptyBodyReturnsHelpfulError(t *testing.T) {
 	c, _ := gin.CreateTestContext(w)
 
 	req, err := http.NewRequest(http.MethodPost, "/", bytes.NewBuffer(nil))
-	assert.NoError(t, err)
+	require.NoError(t, err)
 	req.Header.Set("Content-Type", "application/json")
 
 	c.Request = req
@@ -28,11 +29,11 @@ func TestJSONBindingEmptyBodyReturnsHelpfulError(t *testing.T) {
 	var r Req
 	err = c.ShouldBindJSON(&r)
 
-	assert.Error(t, err)
+	require.Error(t, err)
 
-	// Current behavior returns plain "EOF", which is not helpful.
-	assert.NotEqual(t, "EOF", err.Error(), "error message should not be plain EOF")
+	// Error message should be more descriptive than plain EOF,
+	// while still preserving io.EOF via wrapping.
+	assert.NotEqual(t, "EOF", err.Error())
 	assert.Contains(t, err.Error(), "empty request body")
 	assert.ErrorIs(t, err, io.EOF)
-
 }