validator: Check for common typo of "scheme_preference" branding prop…

…erty

Resolves: #626

src/as-validator-issue-tag.h

@@ -1133,6 +1133,12 @@ AsValidatorIssueTag as_validator_issue_tag_list[] =  {
 	  N_("The value of this color scheme preference is not valid."),
 	},
 
+	{ "branding-color-scheme-wrong-property",
+	  AS_ISSUE_SEVERITY_ERROR,
+	  /* TRANSLATORS: Please do not translate AppStream tag and property names (in backticks). */
+	  N_("The name of the color scheme property is wrong. It should be `scheme_preference`."),
+	},
+
 	{ "branding-color-invalid",
 	  AS_ISSUE_SEVERITY_ERROR,
 	  N_("This color is not a valid HTML color code."),

src/as-validator.c

@@ -2947,6 +2947,16 @@ as_validator_check_branding (AsValidator *validator, xmlNode *node)
 							tmp);
 			g_free (tmp);
 
+			/* catch a common typo */
+			tmp = as_xml_get_prop_value (iter, "schema_preference");
+			if (tmp != NULL)
+				as_validator_add_issue (validator,
+							iter,
+							"branding-color-scheme-wrong-property",
+							"%s",
+							"schema_preference");
+			g_free (tmp);
+
 			tmp = as_xml_get_node_value (iter);
 			len = strlen (tmp);
 			if (!g_str_has_prefix (tmp, "#") || (len != 7 && len != 9))