fix: skip validating unknown version names (#123)

Same problem as seen in #115.

This fixes a problem where having multiple template version names
manually set using Terraform variables would always return a duplicate
name error, as Terraform would mark the attribute, although it is
required and already written in the config, as Unknown before calling
our custom validator. This unknown value is only ever passed to the
validator, never `Create` or `Update`.

Knowing this, we see the same problem exists for all attributes we read
in our custom validator. The only remaining one is `active`, where we
check at least one version is marked as active. In this case, we also
need to skip validating `active` if any of the booleans are unknown.

We previously didn't have any tests that explicitly used Terraform
variables, so this PR adds one, in case the behaviour of these variable
set attributes is changed in the future.

Author: ethanndickson

internal/provider/template_resource.go

@@ -896,9 +896,27 @@ func (a *activeVersionValidator) ValidateList(ctx context.Context, req validator
 		return
 	}
 
+	// Check all versions have unique names
+	uniqueNames := make(map[string]struct{})
+	for _, version := range data {
+		if version.Name.IsNull() || version.Name.IsUnknown() {
+			continue
+		}
+		if _, ok := uniqueNames[version.Name.ValueString()]; ok {
+			resp.Diagnostics.AddError("Client Error", fmt.Sprintf("Template version names must be unique. `%s` appears twice.", version.Name.ValueString()))
+			return
+		}
+		uniqueNames[version.Name.ValueString()] = struct{}{}
+	}
+
 	// Check if only one item in Version has active set to true
 	active := false
 	for _, version := range data {
+		// `active` is required, so if it's null or unknown, this is Terraform
+		// requesting an early validation.
+		if version.Active.IsNull() || version.Active.IsUnknown() {
+			return
+		}
 		if version.Active.ValueBool() {
 			if active {
 				resp.Diagnostics.AddError("Client Error", "Only one template version can be active at a time.")
@@ -910,19 +928,6 @@ func (a *activeVersionValidator) ValidateList(ctx context.Context, req validator
 	if !active {
 		resp.Diagnostics.AddError("Client Error", "At least one template version must be active.")
 	}
-
-	// Check all versions have unique names
-	uniqueNames := make(map[string]struct{})
-	for _, version := range data {
-		if version.Name.IsNull() {
-			continue
-		}
-		if _, ok := uniqueNames[version.Name.ValueString()]; ok {
-			resp.Diagnostics.AddError("Client Error", "Template version names must be unique.")
-			return
-		}
-		uniqueNames[version.Name.ValueString()] = struct{}{}
-	}
 }
 
 var _ validator.List = &activeVersionValidator{}

internal/provider/template_resource_test.go

@@ -648,6 +648,62 @@ func TestAccTemplateResourceAGPL(t *testing.T) {
 	})
 }
 
+func TestAccTemplateResourceVariables(t *testing.T) {
+	cfg := `
+provider coderd {
+	url   = "%s"
+	token = "%s"
+}
+
+data "coderd_organization" "default" {
+  is_default = true
+}
+
+variable "PRIOR_GIT_COMMIT_SHA" {
+  default = "abcdef"
+}
+
+variable "CURRENT_GIT_COMMIT_SHA" {
+  default = "ghijkl"
+}
+
+variable "ACTIVE" {
+  default = true
+}
+
+resource "coderd_template" "sample" {
+  name                  = "example-template"
+  versions = [
+    {
+      name = "${var.PRIOR_GIT_COMMIT_SHA}"
+      directory = "../../integration/template-test/example-template"
+      active    = var.ACTIVE
+    },
+    {
+      name = "${var.CURRENT_GIT_COMMIT_SHA}"
+      directory = "../../integration/template-test/example-template"
+      active    = false
+    }
+  ]
+}`
+
+	ctx := context.Background()
+	client := integration.StartCoder(ctx, t, "template_acc", false)
+
+	cfg = fmt.Sprintf(cfg, client.URL.String(), client.SessionToken())
+
+	resource.Test(t, resource.TestCase{
+		PreCheck:                 func() { testAccPreCheck(t) },
+		IsUnitTest:               true,
+		ProtoV6ProviderFactories: testAccProtoV6ProviderFactories,
+		Steps: []resource.TestStep{
+			{
+				Config: cfg,
+			},
+		},
+	})
+}
+
 type testAccTemplateResourceConfig struct {
 	URL   string
 	Token string