go - How to mock fiber context

I've been trying to mock a fiber.Ctx but I have not been able to make it work I have been getting this error:

>--- FAIL: TestCheckHeaders (0.00s)
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x12085f0]

The code that I am trying to test:

CheckHeaders.go

 package middleware

 import "github.com/gofiber/fiber/v2"

 func CheckHeaders(c *fiber.Ctx) error {
	headers := c.GetReqHeaders()
	if headers["headerValue"] == "true"{
		return c.Next()
	} else {
		return c.SendStatus(401)

	}
 }

CheckHeaders_test.go

 package middleware

 import (
	"testing"
	"github.com/gofiber/fiber/v2"
 )

 func TestCheckHeaders(t *testing.T) {
	type args struct {
		c *fiber.Ctx
	}
	fiberContext := fiber.Ctx{}

	tests := []struct {
		name    string
		args    args
		wantErr bool
	}{
		{name: "test 1",
			args:    args{c: &fiberContext},
			wantErr: true,
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if err := CheckHeaders(tt.args.c); (err != nil) != tt.wantErr {
				t.Errorf("CheckHeaders() error = %v, wantErr %v", err,tt.wantErr)
			}
		})
	}
   }

This was how I set up a new context that I could manipulate for testing. Hope it helps.

app := fiber.New()
c := app.AcquireCtx(&fasthttp.RequestCtx{})

c will be a fresh *fiber.Ctx.

You can create your own interface with methods you need to use from fiber.Ctx struct and make mock for the interface.

After that you are going to handle fiber.Ctx as implementation of for example Ctxer interface so you will be able to mock it using https://github.com/golang/mock and use the mock in your tests.

It's gonna look like this

type Ctxer interface {
	GetReqHeaders() map[string]string
	Next() (err error)
	SendStatus(status int) error
}

func CheckHeaders(c Ctxer) error {
	headers := c.GetReqHeaders()
	if headers["headerValue"] == "true" {
		return c.Next()
	} else {
		return c.SendStatus(401)
	}
}