This reverts commit 334f399ee36e1ea1833298c1a72354af001d01aa, reversing
changes made to 45a5d28bad92bef23832fdc88a4806c911c6fc52.
When testing against Windows SSH the Powershell script fails to parse
the newly added if statement.
This change sets the ErrorActionPreference and wraps the script execution in a Try/Catch statement so that the provisioner can capture any errors encountered when running the script. In addition to the try/catch the `&` operator is replaced by the `.` sourcing operator to ensure the script is executed in the same scope as the parent command (so that errors bubble up properly).
Tests after change
```
⇶ ACC_TEST_BUILDERS=amazon-ebs ACC_TEST_PROVISIONERS=powershell go test ./provisioner/powershell/... -timeout=1h
ok github.com/hashicorp/packer/provisioner/powershell 915.865s
```
This function can be used to check if a Provisioner has been marked for testing within the ACC_TEST_PROVISIONERS environment variable.
While testing I found that the shell acceptance test were also running when trying to run powershell tests.
Before change
```
⇶ ACC_TEST_BUILDERS=amazon-ebs ACC_TEST_PROVISIONERS=powershell go test -v ./provisioner/shell/... -timeout=1h
=== RUN
TestShellProvisioner/testing_amazon-ebs_builder_against_shell_provisioner
2020/04/06 15:18:12 ui: amazon-ebs: output will be in this color.
2020/04/06 15:18:12 ui:
2020/04/06 15:18:12 Build debug mode: false
2020/04/06 15:18:12 Force build: false
2020/04/06 15:18:12 On error:
2020/04/06 15:18:12 Preparing build: amazon-ebs
2020/04/06 15:18:12 Waiting on builds to complete...
2020/04/06 15:18:12 Starting build run: amazon-ebs
2020/04/06 15:18:12 Running builder: amazon-ebs
```
After changes
```
⇶ ACC_TEST_BUILDERS=amazon-ebs ACC_TEST_PROVISIONERS=powershell go test -v ./provisioner/shell/... -timeout=1h
--- SKIP: TestShellProvisioner (0.00s)
provisioners.go:88: Provisioner "shell" not defined in ACC_TEST_PROVISIONERS
```
* Modifies the amazon-ebs builder with a windows build configuration
```
⇶ ACC_TEST_BUILDERS=amazon-ebs ACC_TEST_PROVISIONERS=powershell go test -v ./provisioner/powershell/... -run=TestPowershellProvisioner_Inline
--- PASS: TestPowershellProvisioner_Inline (256.50s)
--- PASS: TestPowershellProvisioner_Inline/testing_amazon-ebs_builder_against_powershell_provisioner (256.50s)
PASS
ok github.com/hashicorp/packer/provisioner/powershell 256.525s
```
