fix(integration): support special characters in exec module (#113)

This commit supports passing in environment variables with special
characters to scripts in our "exec" module. The testcase has been
modified to exemplify this functionality. Prior to this change, the
testcase would fail due the variable getting clobbered after the first
argument:

```
aws: error: argument --output: expected one argument
```

integration/modules/exec/exec

@@ -2,8 +2,8 @@
 set -o pipefail
 # source environment variables from a JSON blob from stdin
 STDIN=$(</dev/stdin)
-ENV=$(echo $STDIN | jq -r "to_entries|map(\"\(.key)=\(.value|tostring)\")|.[]")
-export $ENV
+ENV=$(echo "$STDIN" | jq -r 'to_entries | map("\(.key)=\(.value)") | @sh')
+eval "export ${ENV}"
 
 # if debug file is provided, write out and wait for it to be deleted
 # before proceeding

integration/modules/exec/variables.tf

@@ -14,6 +14,7 @@ variable "args" {
   nullable    = false
   default     = []
 }
+
 variable "env_vars" {
   description = <<-EOF
     Environment variables

integration/scripts/check_bucket_not_empty

@@ -6,4 +6,5 @@ DIE() { echo "$*" 1>&2; exit 1; }
 [[ ! -z "${SOURCE:-}" ]] || DIE "source not set"
 
 echo "listing ${SOURCE}"
-[[ ! -z $(aws s3 ls ${SOURCE}) ]] || DIE "bucket is empty"
+RESULT=$(aws s3 ls ${SOURCE} ${OPTS:-})
+[[ ! -z ${RESULT} ]] || DIE "bucket is empty"

integration/tests/simple.tftest.hcl

@@ -13,11 +13,12 @@ run "check" {
     command = "./scripts/check_bucket_not_empty"
     env_vars = {
       SOURCE = run.setup.access_point.bucket
+      OPTS   = "--output json"
     }
   }
 
   assert {
-    condition     = output.exitcode != 0
+    condition     = output.error == "bucket is empty"
     error_message = "Bucket isn't empty"
   }
 }