diff --git a/api_test.go b/api_test.go
index 81895c8..af8f87d 100644
--- a/api_test.go
+++ b/api_test.go
@@ -1,15 +1,67 @@
 package telebot
 
 import (
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
 )
 
+// testPayload implements json.Marshaler
+// to test json encoding error behaviour.
+type testPayload struct{}
+
+func (testPayload) MarshalJSON() ([]byte, error) {
+	return nil, errors.New("test error")
+}
+
+func testRawServer(w http.ResponseWriter, r *http.Request) {
+	switch {
+	// causes EOF error on ioutil.ReadAll
+	case strings.HasSuffix(r.URL.Path, "/testReadError"):
+		// tells the body is 1 byte length but actually it's 0
+		w.Header().Set("Content-Length", "1")
+	// returns unknown telegram error
+	case strings.HasSuffix(r.URL.Path, "/testUnknownError"):
+		data, _ := json.Marshal(struct {
+			Ok          bool   `json:"ok"`
+			Code        int    `json:"error_code"`
+			Description string `json:"description"`
+		}{
+			Ok:          false,
+			Code:        400,
+			Description: "unknown error",
+		})
+
+		w.WriteHeader(400)
+		w.Write(data)
+	}
+}
+
 func TestRaw(t *testing.T) {
 	b, err := newTestBot()
 	assert.NoError(t, err)
 
 	_, err = b.Raw("BAD METHOD", nil)
 	assert.EqualError(t, err, ErrNotFound.Error())
+
+	_, err = b.Raw("", &testPayload{})
+	assert.Error(t, err)
+
+	srv := httptest.NewServer(http.HandlerFunc(testRawServer))
+	defer srv.Close()
+
+	b.URL = srv.URL
+	b.client = srv.Client()
+
+	_, err = b.Raw("testReadError", nil)
+	assert.EqualError(t, err, "telebot: "+io.ErrUnexpectedEOF.Error())
+
+	_, err = b.Raw("testUnknownError", nil)
+	assert.EqualError(t, err, "telegram: unknown error (400)")
 }