Improve validation for universal login template body

internal/auth0/branding/resource.go

@@ -8,10 +8,10 @@ import (
 	"github.com/hashicorp/terraform-plugin-sdk/v2/diag"
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/id"
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
-	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/validation"
 
 	"github.com/auth0/terraform-provider-auth0/internal/config"
 	internalError "github.com/auth0/terraform-provider-auth0/internal/error"
+	internalValidation "github.com/auth0/terraform-provider-auth0/internal/validation"
 )
 
 var errNoCustomDomain = fmt.Errorf(
@@ -94,7 +94,7 @@ func NewResource() *schema.Resource {
 						"body": {
 							Type:         schema.TypeString,
 							Required:     true,
-							ValidateFunc: validation.StringIsNotEmpty,
+							ValidateFunc: internalValidation.UniversalLoginTemplateContainsCorrectTags,
 							Description:  "The html template for the New Universal Login Experience.",
 						},
 					},

internal/auth0/branding/resource_test.go

@@ -142,7 +142,7 @@ func TestAccBranding(t *testing.T) {
 			},
 			{
 				Config:      testAccBrandingConfigThrowsAValidationErrorIfUniversalLoginBodyIsEmpty,
-				ExpectError: regexp.MustCompile("expected \"universal_login.0.body\" to not be an empty string"),
+				ExpectError: regexp.MustCompile("expected \"universal_login.0.body\" to contain a single auth0:head tag and at least one auth0:widget tag"),
 			},
 			{
 				Config: testAccBrandingConfigRemovesUniversalLoginTemplate,

internal/validation/validation.go

@@ -3,6 +3,7 @@ package validation
 import (
 	"fmt"
 	"net/url"
+	"strings"
 )
 
 // IsURLWithHTTPSorEmptyString is a validation func that checks
@@ -40,3 +41,20 @@ func IsURLWithHTTPSorEmptyString(rawURL interface{}, key string) ([]string, []er
 
 	return nil, nil
 }
+
+// UniversalLoginTemplateContainsCorrectTags is a validation func that checks
+// that the given universal login template body contains the correct tags.
+func UniversalLoginTemplateContainsCorrectTags(rawBody interface{}, key string) ([]string, []error) {
+	v, ok := rawBody.(string)
+	if !ok {
+		return nil, []error{fmt.Errorf("expected type of %q to be string", key)}
+	}
+
+	if strings.Contains(v, "{%- auth0:head -%}") && strings.Contains(v, "{%- auth0:widget -%}") {
+		return nil, nil
+	}
+
+	return nil, []error{
+		fmt.Errorf("expected %q to contain a single auth0:head tag and at least one auth0:widget tag", key),
+	}
+}

internal/validation/validation_test.go

@@ -74,3 +74,50 @@ func TestIsURLWithHTTPSorEmptyString(t *testing.T) {
 		})
 	}
 }
+
+func TestUniversalLoginTemplateContainsCorrectTags(t *testing.T) {
+	tests := []struct {
+		name          string
+		input         interface{}
+		key           string
+		expectedError string
+	}{
+		{
+			name:          "valid input",
+			input:         `Some content {%- auth0:head -%} More content {%- auth0:widget -%}`,
+			key:           "testKey",
+			expectedError: "",
+		},
+		{
+			name:          "missing auth0:head tag",
+			input:         `Some content More content {%- auth0:widget -%}`,
+			key:           "testKey",
+			expectedError: "expected \"testKey\" to contain a single auth0:head tag and at least one auth0:widget tag",
+		},
+		{
+			name:          "missing auth0:widget tag",
+			input:         `Some content {%- auth0:head -%} More content`,
+			key:           "testKey",
+			expectedError: "expected \"testKey\" to contain a single auth0:head tag and at least one auth0:widget tag",
+		},
+		{
+			name:          "incorrect input type",
+			input:         42,
+			key:           "testKey",
+			expectedError: "expected type of \"testKey\" to be string",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			_, errors := UniversalLoginTemplateContainsCorrectTags(test.input, test.key)
+
+			if test.expectedError != "" {
+				assert.EqualError(t, errors[0], test.expectedError)
+				return
+			}
+
+			assert.Len(t, errors, 0)
+		})
+	}
+}