chore: helm_release do not allow duplicate set values

helm/resource_helm_release.go

@@ -1280,8 +1280,8 @@ func getValues(ctx context.Context, model *HelmReleaseModel) (map[string]interfa
 	if !model.Set.IsNull() {
 		tflog.Debug(ctx, "Processing Set attribute")
 		var setList []setResourceModel
-		setDiags := model.Set.ElementsAs(ctx, &setList, false)
-		diags.Append(setDiags...)
+		diags.Append(model.Set.ElementsAs(ctx, &setList, false)...)
+		diags.Append(validateNoDuplicateSetNames(setList)...)
 		if diags.HasError() {
 			return nil, diags
 		}
@@ -2175,3 +2175,27 @@ func valuesUnknown(plan HelmReleaseModel) bool {
 	}
 	return false
 }
+
+// validateNoDuplicateSetNames checks for duplicate names in set blocks and returns
+// an error diagnostic if any are found.
+func validateNoDuplicateSetNames(setList []setResourceModel) diag.Diagnostics {
+	var diags diag.Diagnostics
+	seenNames := make(map[string]int)
+
+	for i, set := range setList {
+		name := set.Name.ValueString()
+
+		if prevIndex, seen := seenNames[name]; seen {
+			diags.AddError(
+				"Duplicate value name in set",
+				fmt.Sprintf("The name '%s' is specified multiple times in 'set' blocks (at indices %d and %d). "+
+					"Each name should only be specified once.", name, prevIndex, i),
+			)
+			return diags
+		}
+
+		seenNames[name] = i
+	}
+
+	return diags
+}

helm/resource_helm_release_test.go

@@ -635,6 +635,25 @@ func TestAccResourceRelease_updateSetValue(t *testing.T) {
 	})
 }
 
+func TestAccResourceRelease_duplicateSetNames(t *testing.T) {
+	name := randName("test-duplicate-set-names")
+	namespace := createRandomNamespace(t)
+	defer deleteNamespace(t, namespace)
+
+	resource.Test(t, resource.TestCase{
+		ProtoV6ProviderFactories: protoV6ProviderFactories(),
+		Steps: []resource.TestStep{
+			{
+				// Config with duplicate set names should fail
+				Config: testAccHelmReleaseConfigDuplicateSetNames(
+					testResourceName, namespace, name, "1.2.3",
+				),
+				ExpectError: regexp.MustCompile("Duplicate value name in set"),
+			},
+		},
+	})
+}
+
 func TestAccResourceRelease_validation(t *testing.T) {
 	invalidName := "this-helm-release-name-is-longer-than-53-characters-long"
 	namespace := createRandomNamespace(t)
@@ -1038,6 +1057,34 @@ func testAccHelmReleaseConfigSet(resource, ns, name, version, setValue string) s
 	`, resource, name, ns, testRepositoryURL, version, setValue)
 }
 
+func testAccHelmReleaseConfigDuplicateSetNames(resource, ns, name, version string) string {
+	return fmt.Sprintf(`
+		resource "helm_release" "%s" {
+			name        = %q
+			namespace   = %q
+			description = "Test"
+			repository  = %q
+			chart       = "test-chart"
+			version     = %q
+
+			set = [
+				{
+					name  = "foo"
+					value = "bar"
+				},
+				{
+					name  = "fizz"
+					value = "buzz"
+				},
+				{
+					name  = "foo"
+					value = "different value"
+				}
+			]
+		}
+	`, resource, name, ns, testRepositoryURL, version)
+}
+
 func testAccHelmReleaseConfigSetNull(resource, ns, name, version string) string {
 	return fmt.Sprintf(`
 		resource "helm_release" "%s" {