Fix default function name

As noted in aws#46, the function name is derived from
the URL used to invoke it. The emulator uses `function`
in the API endpoint, but the `AWS_LAMBDA_FUNCTION_NAME`
environment variable is set to `test_function`. This
is an inconsistency between the emulator and the AWS
environment.

Author: skwashd

Diff for: cmd/aws-lambda-rie/handlers.go

@@ -95,7 +95,7 @@ func InvokeHandler(w http.ResponseWriter, r *http.Request, sandbox Sandbox) {
 	invokeStart := time.Now()
 	invokePayload := &interop.Invoke{
 		ID:                 uuid.New().String(),
-		InvokedFunctionArn: fmt.Sprintf("arn:aws:lambda:us-east-1:012345678912:function:%s", GetenvWithDefault("AWS_LAMBDA_FUNCTION_NAME", "test_function")),
+		InvokedFunctionArn: fmt.Sprintf("arn:aws:lambda:us-east-1:012345678912:function:%s", GetenvWithDefault("AWS_LAMBDA_FUNCTION_NAME", "function")),
 		TraceID:            r.Header.Get("X-Amzn-Trace-Id"),
 		LambdaSegmentID:    r.Header.Get("X-Amzn-Segment-Id"),
 		Payload:            bytes.NewReader(bodyBytes),
@@ -175,7 +175,7 @@ func InitHandler(sandbox Sandbox, functionVersion string, timeout int64) (time.T
 	additionalFunctionEnvironmentVariables["AWS_LAMBDA_LOG_STREAM_NAME"] = "$LATEST"
 	additionalFunctionEnvironmentVariables["AWS_LAMBDA_FUNCTION_VERSION"] = "$LATEST"
 	additionalFunctionEnvironmentVariables["AWS_LAMBDA_FUNCTION_MEMORY_SIZE"] = "3008"
-	additionalFunctionEnvironmentVariables["AWS_LAMBDA_FUNCTION_NAME"] = "test_function"
+	additionalFunctionEnvironmentVariables["AWS_LAMBDA_FUNCTION_NAME"] = "function"
 
 	// Forward Env Vars from the running system (container) to what the function can view. Without this, Env Vars will
 	// not be viewable when the function runs.
@@ -194,7 +194,7 @@ func InitHandler(sandbox Sandbox, functionVersion string, timeout int64) (time.T
 		AwsSecret:         os.Getenv("AWS_SECRET_ACCESS_KEY"),
 		AwsSession:        os.Getenv("AWS_SESSION_TOKEN"),
 		XRayDaemonAddress: "0.0.0.0:0", // TODO
-		FunctionName:      GetenvWithDefault("AWS_LAMBDA_FUNCTION_NAME", "test_function"),
+		FunctionName:      GetenvWithDefault("AWS_LAMBDA_FUNCTION_NAME", "function"),
 		FunctionVersion:   functionVersion,
 
 		CustomerEnvironmentVariables: additionalFunctionEnvironmentVariables,

Diff for: test/integration/testdata/main.py

@@ -25,13 +25,13 @@ def check_env_var_handler(event, context):
 
 def assert_env_var_is_overwritten(event, context):
     print(os.environ.get("AWS_LAMBDA_FUNCTION_NAME"))
-    if os.environ.get("AWS_LAMBDA_FUNCTION_NAME") == "test_function":
+    if os.environ.get("AWS_LAMBDA_FUNCTION_NAME") == "function":
         raise("Function name was not overwritten")
     else:
         return "My lambda ran succesfully"
 
 def assert_lambda_arn_in_context(event, context):
-    if context.invoked_function_arn == f"arn:aws:lambda:us-east-1:012345678912:function:{os.environ.get('AWS_LAMBDA_FUNCTION_NAME', 'test_function')}":
+    if context.invoked_function_arn == f"arn:aws:lambda:us-east-1:012345678912:function:{os.environ.get('AWS_LAMBDA_FUNCTION_NAME', 'function')}":
         return "My lambda ran succesfully"
     else:
         raise("Function Arn was not there")