How to unit test extraction from cookie in Gin Gonic

Question

I'm using gin gonic. I've a function that extracts a token from a cookie, which actually works. I'm using this function in a route handler and want to test the handler function, but I don't know how.

Function:

// Extracts token from a cookie
func tokenFromCookie(c *gin.Context, name string) (string, error) {
    token, err := c.Cookie(name)
    if err != nil {
        return "", err
    }

    return token, nil
}

Route:

func RefreshTokenHandler(accessTokenKey string, refreshTokenKey string) gin.HandlerFunc {
fn := func(c *gin.Context) {
    token, err := tokenFromCookie(c, "refresh_token")
    if err != nil {
        _ = c.Error(err).SetMeta(noCookie)
        return
    }
    c.JSON(http.StatusOK, gin.H{
        "token":  token,
    })
})

Route definition:

func CreateRoutes(r *gin.Engine) *gin.Engine {

    r.Use(errorHandler)

    // Auth
    auth := r.Group("/auth")
    {
        auth.GET("/refresh-token", RefreshTokenHandler(accessTokenSignatureKey, refreshTokenSignatureKey))
    }

    return r
}

Unit test:

func TestRefreshTokenHandler(t *testing.T) {
    req, _ := http.NewRequest("GET", "/auth/refresh-token", nil)
    req.AddCookie(&http.Cookie{
        Name: "refresh_token",
        Value:  "token",
        MaxAge:   604800, 
        Expires:  time.Now().Add(time.Hour * 24 * 7),
        Path:     "/",
        Domain:   "127.0.0.1",
        HttpOnly: true,
        SameSite: http.SameSiteNoneMode,
        Secure:   secure
        }
    )

    w := httptest.NewRecorder()
    router.ServeHTTP(w, req)
    got := w.Code
    if gotCode != 200 {
        t.Errorf("GET /auth/refresh-token; got %d, want 200", got)
    }
}

The tokenFromCookie() function throws an error though:

http: named cookie not present

This is a similar unit test that I found in the gin gonic repo:

func TestContextGetCookie(t *testing.T) {
    c, _ := CreateTestContext(httptest.NewRecorder())
    c.Request, _ = http.NewRequest("GET", "/get", nil)
    c.Request.Header.Set("Cookie", "user=gin")
    cookie, _ := c.Cookie("user")
    assert.Equal(t, "gin", cookie)

    _, err := c.Cookie("nokey")
    assert.Error(t, err)
}

Yet I don't understand why my code doesn't work and how to re-write it.

Answer 1

To view the list cookies you can try this:

fmt.Println(c.Request.Cookies())

I don't understand the point of creating new function tokenFromCookie.

func RefreshTokenHandler(accessTokenKey string, refreshTokenKey string) gin.HandlerFunc {
fn := func(c *gin.Context) {
    //token, err := tokenFromCookie(c, "refresh_token")
    token, err := c.Cookie("refresh_token")
    if err != nil {
        _ = c.Error(err).SetMeta(noCookie)
        return
    }
    c.JSON(http.StatusOK, gin.H{
        "token":  token,
    })
})