Add TerraTest and examples (#2)

Adds TerraTest https://terratest.gruntwork.io/
Adds testing for
- Make sure the public subnets are public
- Make sure the private subnets are not publically routable
- Make sure that when we ask for a single nat gateway we only get one

Author: damacus

examples/main.tf

@@ -0,0 +1,24 @@
+module "main" {
+  single_nat_gw = true
+  source        = "../."
+}
+
+output "public_subnets" {
+  value = module.main.public_subnets
+}
+
+output "private_subnets" {
+  value = module.main.private_subnets
+}
+
+output "database_subnets" {
+  value = module.main.database_subnets
+}
+
+output "vpc" {
+  value = module.main.vpc
+}
+
+output "nat_gws" {
+  value = module.main.aws_nat_gateways
+}

main.tf

@@ -5,6 +5,10 @@ resource "aws_vpc" "vpc" {
   tags                 = merge(local.tags, { "Name" = "VPC" })
 }
 
+output "vpc" {
+  value = aws_vpc.vpc
+}
+
 data "aws_region" "current" {}
 
 resource "aws_vpc_endpoint" "s3" {

outputs.tf

@@ -13,3 +13,7 @@ output "private_subnets" {
 output "database_subnets" {
   value = aws_subnet.database.*.id
 }
+
+output "aws_nat_gateways" {
+  value = aws_nat_gateway.nat_gw
+}

test/go.mod

@@ -0,0 +1,8 @@
+module damacus/terraform-module-vpc
+
+go 1.14
+
+require (
+	github.com/gruntwork-io/terratest v0.26.6
+	github.com/stretchr/testify v1.5.1
+)