The resource is build so it can attach and detach the Internet Gateway
from a VPC, but as the schema has `Required` and `ForceNew` both set
to `true` for the vpc_id field it will never use these capabilities.
This is a refactored solution for PR #616. Functionally this is still
the same change, but it’s implemented a lot cleaner with less code and
less changes to existing parts of TF.
It’s not enough to only check if no new value is set. It can also be
that a new value is set, but contains a variable that cannot be
interpolated until a depending resource is created during the apply
fase.
I actually found this one as one of the acceptance tests for the AWS
ELB resource was failing. It failed with the following error:
```
--- FAIL: TestAccAWSELB_InstanceAttaching (177.83 seconds)
testing.go:121: Step 1 error: Error applying: aws_elb.bar: diffs
didn't match during apply. This is a bug with the resource provider,
please report a bug.
FAIL
exit status 1
FAIL github.com/hashicorp/terraform/builtin/providers/aws 177.882s
```
After a quick look I noticed it was actually a bug in core TF so added
the test and made sure all unit tests and AWS acceptance tests are now
running successfully.
Running the tests without these changes results in this error first:
```
--- FAIL: TestAccAWSNetworkAclsOnlyIngressRulesChange (24.92 seconds)
testing.go:121: Step 0 error: Check failed: Invalid number of ingress
entries found; count = %!s(int=3)
FAIL
exit status 1
FAIL github.com/hashicorp/terraform/builtin/providers/aws 24.974s
```
And after fixing that one you also get a few unexpected values due to
an expected order mismatch between the items in the set versus the
items in the config.
Those are also fixed, so the test is passing now.
Sander van Harmelen