feat(context): return GIN Context from Value method (#2825)

context.go

@@ -39,6 +39,9 @@ const (
 // BodyBytesKey indicates a default body bytes key.
 const BodyBytesKey = "_gin-gonic/gin/bodybyteskey"
 
+// ContextKey is the key that a Context returns itself for.
+const ContextKey = "_gin-gonic/gin/contextkey"
+
 // abortIndex represents a typical value used in abort functions.
 const abortIndex int8 = math.MaxInt8 >> 1
 
@@ -1163,6 +1166,9 @@ func (c *Context) Value(key any) any {
 	if key == 0 {
 		return c.Request
 	}
+	if key == ContextKey {
+		return c
+	}
 	if keyAsString, ok := key.(string); ok {
 		if val, exists := c.Get(keyAsString); exists {
 			return val

context_test.go

@@ -1880,6 +1880,7 @@ func TestContextGolangContext(t *testing.T) {
 	assert.Equal(t, ti, time.Time{})
 	assert.False(t, ok)
 	assert.Equal(t, c.Value(0), c.Request)
+	assert.Equal(t, c.Value(ContextKey), c)
 	assert.Nil(t, c.Value("foo"))
 
 	c.Set("foo", "bar")