http-lambda-invoker_test.go

package main

import (
	"encoding/json"
	"io/ioutil"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	"github.com/aws/aws-sdk-go/service/lambda"
	"github.com/aws/aws-sdk-go/service/lambda/lambdaiface"
)

type restRequest struct {
	Body   string
	Method string
	Path   string
}

type exchange struct {
	Request  restRequest
	Response restResponse
}

type mockLambdaClient struct {
	lambdaiface.LambdaAPI
	Resp lambda.InvokeOutput
}

func (m mockLambdaClient) Invoke(*lambda.InvokeInput) (*lambda.InvokeOutput, error) {
	return &m.Resp, nil
}

func runTest(t *testing.T, e exchange) {
	request, response := e.Request, e.Response
	req, err := http.NewRequest(request.Method, request.Path, ioutil.NopCloser(strings.NewReader(request.Body)))
	if err != nil {
		t.Fatal(err)
	}
	rr := httptest.NewRecorder()

	payload, err := json.Marshal(response)
	if err != nil {
		t.Fatal(err)
	}
	status := int64(200)
	resp := struct {
		Resp lambda.InvokeOutput
	}{
		Resp: lambda.InvokeOutput{
			Payload:    payload,
			StatusCode: &status,
		},
	}

	l := LambdaClient{
		mockLambdaClient{Resp: resp.Resp},
	}

	l.invokeLambda(rr, req)

	// Body equals mocked response
	if b := rr.Body.String(); b != response.Body {
		t.Errorf("handler returned unexpected body: got %v want %v",
			b, response.Body)
	}

	// Status code equals mocked response
	if s := rr.Code; s != response.StatusCode {
		t.Errorf("handler returned wrong status code: got %v want %v",
			s, response.StatusCode)
	}

	// Check CORS header
	if cors := rr.Header().Get(("Access-Control-Allow-Origin")); cors != "*" {
		t.Errorf("handler returned unexpected cors header: got %v want *", cors)
	}

	// Check content-type header
	if contentType := rr.Header().Get(("Content-Type")); contentType != response.Headers["content-type"] {
		t.Errorf("handler returned unexpected content-type header: got %v want %v", contentType, response.Headers["content-type"])
	}

	// No content-length header
	if l := rr.Header().Get(("content-length")); l != "" {
		t.Errorf("handler returned unexpected cors header: got %v want ''", l)
	}
}

func TestLambdaInvoke(t *testing.T) {

	responses := []exchange{
		{
			Request: restRequest{
				Method: "GET",
				Path:   "/",
			},
			Response: restResponse{
				Body:       "{\"hasPayload\":true}",
				Headers:    nil,
				StatusCode: 200,
			},
		},
		{
			Request: restRequest{
				Method: "GET",
				Path:   "/props",
			},
			Response: restResponse{
				Body:       "{\"hasPayload\":true,\"AnotherProp\":123}",
				Headers:    map[string]string{"content-type": "application/json"},
				StatusCode: 200,
			},
		},
		{
			Request: restRequest{
				Method: "GET",
				Path:   "/error",
			},
			Response: restResponse{
				Body:       "{\"error\":true}",
				Headers:    nil,
				StatusCode: 500,
			},
		},
		{
			Request: restRequest{
				Body:   "{\"prop\":\"value\"}",
				Method: "POST",
				Path:   "/post",
			},
			Response: restResponse{
				Body:       "",
				Headers:    nil,
				StatusCode: 200,
			},
		},
	}

	for _, response := range responses {
		runTest(t, response)
	}
}