Add the negative test to verify there is logic that enforces the correct extension secret

WrongSecret_test.go

func TestWrongExtensionSecret(t *testing.T) {
        // prepare data
        wrongHeader := make(map[string]string)
        wrongHeader["Authorization"] = "Bearer WRONG-KEY"
        req := events.APIGatewayProxyRequest{
                HTTPMethod: "GET",
                Body:       "",
                Headers:    wrongHeader,
        }

        // run request handlerlogic
        result, err := handler(req)
        assert.IsType(t, nil, err)
        assert.Equal(t, http.StatusOK, result.StatusCode)

        // case specific expectation
        missing := newResponse("Wrong authorization header", http.StatusUnauthorized)
        expected := ignoreTimestamp(missing.Body)
        actual := ignoreTimestamp(result.Body)
        // inspect content
        assert.Equal(t, expected, actual)
}