refactor preflight request test for the addition of middleware

Preflight_test.go

func TestPreflight(t *testing.T) {
        // prep test data
        conf := ebs.NewConfig()
        expectMethods := "POST, GET, OPTIONS, PUT"
        expectHeaders := "Accept, Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization"
        expectOrigin := ""
        req := newTestRequest("OPTIONS")

        // run the handler logic
        result, err := ebs.MiddlewareCORS(conf, handler)(req)
        assert.IsType(t, nil, err)
        assert.Equal(t, http.StatusOK, result.StatusCode)
        // check for expected CORS
        assert.Equal(t, expectMethods, result.Headers["Access-Control-Allow-Methods"])
        assert.Equal(t, expectHeaders, result.Headers["Access-Control-Allow-Headers"])
        assert.Equal(t, expectOrigin, result.Headers["Access-Control-Allow-Origin"])
}