Always validate VCL services after applying changes. (#942)

In PR #733 the validation logic was changed to only attempt validation
of services if they would also be activated, in order to avoid failing
validation of Compute services which do not have WASM packages
attached to them. Unfortunately this breaks customer workflows for VCL
services, as they no longer get feedback about validation failures
until they attempt to activate the service outside of Terraform.

This patch changes the logic so that VCL services are always
validated, even if they will not be activated or staged.

Author: kpfleming

CHANGELOG.md

@@ -7,6 +7,8 @@ ENHANCEMENTS:
 
 BUG FIXES:
 
+- fix(fastly_vcl_service): Always 'validate' services after applying changes.
+
 DEPENDENCIES:
 
 - build(deps): `github.com/hashicorp/terraform-plugin-docs` from 0.19.4 to 0.21.0 ([#937](https://github.com/fastly/terraform-provider-fastly/pull/937))

fastly/base_fastly_service.go

@@ -457,23 +457,18 @@ func resourceServiceUpdate(ctx context.Context, d *schema.ResourceData, meta any
 			}
 		}
 
-		// Only validate the service if `activate = true` or `stage = true`.
-		// This is primarily for compute services with no package defined.
-		// The user needs to set `activate = false` and `stage = false` to prevent errors.
-		// As they can't activate or stage a service without a package.
-		// There's no value showing validation errors to users in 'draft' mode.
-		mustValidate := false
-		if i := d.Get("activate"); i != nil {
-			if i.(bool) {
-				mustValidate = true
-			}
-		}
-		if i := d.Get("stage"); i != nil {
-			if i.(bool) {
-				mustValidate = true
-			}
-		}
-		if mustValidate {
+		// Delivery (VCL) services should always be validated
+		// after changes are made, even if they will not be
+		// activated or staged.
+		//
+		// Compute (WASM) services should only be validated if
+		// they will be activated or staged, since the service
+		// may not have a WASM package attached while it is
+		// 'draft' and validation would fail. If the user is
+		// expecting to activate or stage the service, though,
+		// it must have a WASM package attached and pass
+		// validation.
+		if (serviceDef.GetType() == ServiceTypeVCL) || d.Get("activate").(bool) || d.Get("stage").(bool) {
 			// Validate version.
 			log.Printf("[DEBUG] Validating Fastly Service (%s), Version (%v)", d.Id(), latestVersion)
 			valid, msg, err := conn.ValidateVersion(&gofastly.ValidateVersionInput{