resources.functions: improve validation

resources/resource_transformers/integrity/integrity.go

@@ -91,7 +91,7 @@ func newHash(algo string) (hash.Hash, error) {
 	case "sha512":
 		return sha512.New(), nil
 	default:
-		return nil, fmt.Errorf("unsupported crypto algo: %q, use either md5, sha256, sha384 or sha512", algo)
+		return nil, fmt.Errorf("unsupported hash algorithm: %q, use either md5, sha256, sha384 or sha512", algo)
 	}
 }
 

tpl/resources/resources.go

@@ -145,7 +145,7 @@ func (ns *Namespace) Get(filename any) resource.Resource {
 //
 // A second argument may be provided with an option map.
 //
-// Note: This method does not return any error as a second argument,
+// Note: This method does not return any error as a second return value,
 // for any error situations the error can be checked in .Err.
 func (ns *Namespace) GetRemote(args ...any) resource.Resource {
 	get := func(args ...any) (resource.Resource, error) {
@@ -153,6 +153,10 @@ func (ns *Namespace) GetRemote(args ...any) resource.Resource {
 			return nil, errors.New("must provide an URL")
 		}
 
+		if len(args) > 2 {
+			return nil, errors.New("must not provide more arguments than URL and options")
+		}
+
 		urlstr, err := cast.ToStringE(args[0])
 		if err != nil {
 			return nil, err
@@ -302,8 +306,12 @@ func (ns *Namespace) ExecuteAsTemplate(ctx context.Context, args ...any) (resour
 // Fingerprint transforms the given Resource with a MD5 hash of the content in
 // the RelPermalink and Permalink.
 func (ns *Namespace) Fingerprint(args ...any) (resource.Resource, error) {
-	if len(args) < 1 || len(args) > 2 {
+	if len(args) < 1 {
-		return nil, errors.New("must provide a Resource and (optional) crypto algo")
+		return nil, errors.New("must provide a Resource object")
+	}
+
+	if len(args) > 2 {
+		return nil, errors.New("must not provide more arguments than Resource and hash algorithm")
 	}
 
 	var algo string
@@ -332,9 +340,15 @@ func (ns *Namespace) Minify(r resources.ResourceTransformer) (resource.Resource,
 	return ns.minifyClient.Minify(r)
 }
 
-// ToCSS converts the given Resource to CSS. You can optional provide an Options
+// ToCSS converts the given Resource to CSS. You can optional provide an Options object
-// object or a target path (string) as first argument.
+// as second argument. As an option, you can e.g. specify e.g. the target path (string)
+// for the converted CSS resource.
 func (ns *Namespace) ToCSS(args ...any) (resource.Resource, error) {
+
+	if len(args) > 2 {
+		return nil, errors.New("must not provide more arguments than resource object and options")
+	}
+
 	const (
 		// Transpiler implementation can be controlled from the client by
 		// setting the 'transpiler' option.
@@ -404,6 +418,11 @@ func (ns *Namespace) ToCSS(args ...any) (resource.Resource, error) {
 
 // PostCSS processes the given Resource with PostCSS
 func (ns *Namespace) PostCSS(args ...any) (resource.Resource, error) {
+
+	if len(args) > 2 {
+		return nil, errors.New("must not provide more arguments than resource object and options")
+	}
+
 	r, m, err := resourcehelpers.ResolveArgs(args)
 	if err != nil {
 		return nil, err
@@ -419,6 +438,11 @@ func (ns *Namespace) PostProcess(r resource.Resource) (postpub.PostPublishedReso
 
 // Babel processes the given Resource with Babel.
 func (ns *Namespace) Babel(args ...any) (resource.Resource, error) {
+
+	if len(args) > 2 {
+		return nil, errors.New("must not provide more arguments than resource object and options")
+	}
+
 	r, m, err := resourcehelpers.ResolveArgs(args)
 	if err != nil {
 		return nil, err