/
lambda.go
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/
lambda.go
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package lambda
import (
"bytes"
"context"
"encoding/base64"
"encoding/json"
"errors"
"fmt"
"reflect"
"runtime"
"strings"
"testing"
"github.com/aws/aws-lambda-go/lambda"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/awserr"
"github.com/aws/aws-sdk-go/aws/session"
lambdasvc "github.com/aws/aws-sdk-go/service/lambda"
"github.com/jefflinse/melatonin/expect"
"github.com/jefflinse/melatonin/mt"
)
const (
VersionLatest = "$LATEST"
)
type LambdaAPI interface {
Invoke(input *lambdasvc.InvokeInput) (*lambdasvc.InvokeOutput, error)
}
type TestContext struct {
svc LambdaAPI
}
// DefaultContext returns a LambdaTestContext using a default AWS Lambda service.
func DefaultContext() *TestContext {
svc := lambdasvc.New(session.Must(session.NewSession()))
return NewTestContext(svc)
}
// EmptyContext returns a LambdaTestContext with no configured AWS service.
// It is suitable only for testing local function handlers.
func EmptyContext() *TestContext {
return &TestContext{}
}
// NewLambdaFunctionContext creates a new HTTPTestContext for creating tests that target
// AWS Lambda functions using the provided AWS service.
func NewTestContext(svc LambdaAPI) *TestContext {
return &TestContext{
svc: svc,
}
}
func (c *TestContext) Invoke(functionID string, description ...string) *TestCase {
return newLambdaTestCase(c, functionID, description...)
}
func (c *TestContext) Handle(handlerFn interface{}, description ...string) *TestCase {
return newHandlerTestCase(c, handlerFn, description...)
}
func Invoke(functionID string, description ...string) *TestCase {
return DefaultContext().Invoke(functionID, description...)
}
func Handle(handlerFn interface{}, description ...string) *TestCase {
return EmptyContext().Handle(handlerFn, description...)
}
type TestCase struct {
Desc string
FunctionID string
HandlerFn interface{}
Payload interface{}
Expectations ResponseExpectations
payloadBytes []byte
request *lambdasvc.InvokeInput
tctx *TestContext
}
var _ mt.TestCase = &TestCase{}
func newLambdaTestCase(context *TestContext, functionID string, description ...string) *TestCase {
return &TestCase{
Desc: strings.Join(description, " "),
FunctionID: functionID,
request: &lambdasvc.InvokeInput{
FunctionName: aws.String(functionID),
},
tctx: context,
}
}
func newHandlerTestCase(c *TestContext, handlerFn interface{}, description ...string) *TestCase {
return &TestCase{
Desc: strings.Join(description, " "),
HandlerFn: handlerFn,
}
}
func (tc *TestCase) Action() string {
if tc.FunctionID != "" {
return "INVOKE"
}
return "HANDLE"
}
func (tc *TestCase) Description() string {
if tc.Desc != "" {
return tc.Desc
}
if tc.FunctionID != "" {
return "Invoke " + tc.Target()
}
return "Call " + tc.Target()
}
func (tc *TestCase) Target() string {
if tc.FunctionID != "" {
target := strings.Replace(tc.FunctionID, "arn:aws:lambda:", ":::", 1)
target = strings.Replace(target, ":function:", "::", 1)
return fmt.Sprintf("AWS Lambda (%s)", target)
}
return "AWS Lambda handler (" + functionName(tc.HandlerFn) + ")"
}
func (tc *TestCase) Execute(t *testing.T) (mt.TestResult, error) {
if tc.FunctionID != "" && tc.HandlerFn != nil {
return nil, fmt.Errorf("LambdaTestCase must specify either FunctionID or HandlerFn, not both")
}
var result *TestResult
var err error
if tc.FunctionID != "" {
result, err = tc.invoke()
} else if tc.HandlerFn != nil {
result, err = tc.handle()
}
if err != nil {
return nil, err
}
if len(result.Errors()) == 0 {
result.validateExpectations()
}
return result, nil
}
func (tc *TestCase) AsDryRun() *TestCase {
tc.request.InvocationType = aws.String("DryRun")
tc.Expectations.Status = 204
return tc
}
func (tc *TestCase) Describe(description string) *TestCase {
tc.Desc = description
return tc
}
func (tc *TestCase) WithExecutionLogs() *TestCase {
tc.request.LogType = aws.String("Tail")
return tc
}
func (tc *TestCase) WithPayload(payload interface{}) *TestCase {
tc.Payload = payload
return tc
}
func (tc *TestCase) ExpectFunctionError(err string) *TestCase {
tc.Expectations.FunctionError = err
return tc
}
func (tc *TestCase) ExpectPayload(payload interface{}) *TestCase {
tc.Expectations.Payload = payload
return tc
}
func (tc *TestCase) ExpectExactPayload(payload interface{}) *TestCase {
tc.Expectations.Payload = payload
tc.Expectations.WantExactJSONPayload = true
return tc
}
func (tc *TestCase) ExpectStatus(status int) *TestCase {
tc.Expectations.Status = status
return tc
}
func (tc *TestCase) ExpectVersion(version string) *TestCase {
tc.Expectations.Version = version
return tc
}
func (tc *TestCase) invoke() (*TestResult, error) {
if tc.tctx.svc == nil {
return nil, errors.New("no AWS Lambda service provided")
}
payload, err := tc.requestPayloadBytes()
if err != nil {
return nil, err
}
tc.request.Payload = payload
resp, err := tc.tctx.svc.Invoke(tc.request)
result := &TestResult{
testCase: tc,
InvocationError: err,
Payload: resp.Payload,
}
if resp.ExecutedVersion != nil {
result.Version = *resp.ExecutedVersion
}
if resp.FunctionError != nil {
result.FunctionError = *resp.FunctionError
}
if resp.LogResult != nil {
result.LogBase64 = *resp.LogResult
}
if resp.StatusCode != nil {
result.Status = int(*resp.StatusCode)
}
return result, nil
}
func (tc *TestCase) handle() (*TestResult, error) {
handler := lambda.NewHandler(tc.HandlerFn)
payload, err := tc.requestPayloadBytes()
if err != nil {
return nil, err
}
resp, err := handler.Invoke(context.TODO(), payload)
if err != nil {
return nil, err
}
return &TestResult{
testCase: tc,
Status: 200,
Payload: resp,
}, nil
}
func (tc *TestCase) requestPayloadBytes() ([]byte, error) {
if tc.payloadBytes != nil {
return tc.payloadBytes, nil
}
var payload []byte
if tc.Payload != nil {
var err error
switch v := tc.Payload.(type) {
case []byte:
payload = v
case string:
payload = []byte(v)
case func() []byte:
payload = v()
case func() ([]byte, error):
payload, err = v()
default:
payload, err = json.Marshal(tc.Payload)
}
if err != nil {
return nil, fmt.Errorf("request body: %w", err)
}
}
tc.payloadBytes = payload
return tc.payloadBytes, nil
}
type ResponseExpectations struct {
FunctionError string
Payload interface{}
Status int
Version string
WantExactJSONPayload bool
}
type TestResult struct {
FunctionError string
InvocationError error
LogBase64 string
Payload []byte
Status int
Version string
testCase *TestCase
errors []error
}
var _ mt.TestResult = (*TestResult)(nil)
func (r *TestResult) Errors() []error {
return r.errors
}
func (r *TestResult) Log() (string, error) {
if r.LogBase64 == "" {
return "", nil
}
b, err := base64.StdEncoding.DecodeString(r.LogBase64)
if err != nil {
return "", err
}
return string(b), nil
}
func (r *TestResult) TestCase() mt.TestCase {
return r.testCase
}
func functionName(f interface{}) string {
return runtime.FuncForPC(reflect.ValueOf(f).Pointer()).Name()
}
func parseResponsePayload(body []byte) interface{} {
if len(body) > 0 {
// see if it's a function error response
d := json.NewDecoder(bytes.NewReader(body))
d.DisallowUnknownFields()
funcErrResp := &functionError{}
if err := d.Decode(funcErrResp); err == nil && funcErrResp.Message != nil && funcErrResp.Type != nil {
return funcErrResp
}
var bodyMap map[string]interface{}
if err := json.Unmarshal(body, &bodyMap); err == nil {
return bodyMap
}
var bodyArray []interface{}
if err := json.Unmarshal(body, &bodyArray); err == nil {
return bodyArray
}
b := strings.TrimPrefix(string(body), `"`)
return strings.TrimSuffix(b, `"`)
}
return nil
}
type functionError struct {
Message *string `json:"errorMessage"`
Type *string `json:"errorType"`
}
func (r *TestResult) validateExpectations() {
tc := r.TestCase().(*TestCase)
// Check for an unexpected invocation error.
if r.InvocationError != nil && !(tc.Expectations.Status != 0 && r.Status == tc.Expectations.Status) {
awsErr := r.InvocationError.(awserr.Error)
r.errors = append(r.errors, errors.New(awsErr.Message()))
}
// If the wrong version was executed, that should probably be the next error,
// since it will affect the interpretation of the other errors.
if tc.Expectations.Version != "" && r.Version != tc.Expectations.Version {
r.errors = append(r.errors, fmt.Errorf("expected to execute version %q, but executed version %q", tc.Expectations.Version, r.Version))
}
if tc.Expectations.Status != 0 && r.Status != tc.Expectations.Status {
r.errors = append(r.errors, fmt.Errorf("expected status %d, got %d", tc.Expectations.Status, r.Status))
}
if tc.Expectations.FunctionError != "" && r.FunctionError == "Unhandled" {
errPayload := parseResponsePayload(r.Payload).(*functionError)
if *errPayload.Message != tc.Expectations.FunctionError {
r.errors = append(r.errors, fmt.Errorf("expected function error %q, got %q", tc.Expectations.FunctionError, *errPayload.Message))
}
} else {
if r.FunctionError != "" {
r.errors = append(r.errors, fmt.Errorf("expected no function error, got %q", r.FunctionError))
}
}
if tc.Expectations.Payload != nil {
body := parseResponsePayload(r.Payload)
if errs := expect.Value("body", tc.Expectations.Payload, body, tc.Expectations.WantExactJSONPayload); len(errs) > 0 {
r.errors = append(r.errors, errs...)
}
}
}
var _ mt.TestResult = &TestResult{}