check filename for .png extension

Without a correct file type extension, phantomjs will fail
silently

diff --git a/test/phantom/screenshot.js b/test/phantom/screenshot.js
index 40f9937..8fea863 100644 (file)
--- a/test/phantom/screenshot.js
+++ b/test/phantom/screenshot.js
@@ -5,11 +5,23 @@ var url = system.args[1] || 'http://www.indexdata.com/';
 var file_png = system.args[2] || 'indexdata.png';
 var timeout = system.args[5] ? system.args[5] : 0.2;
 
-if (system.args.length === 1) {
+function usage (message) {
+    if (message) {
+        console.log(message + "\n");
+    }
     console.log('Usage: screenshot.js <some URL> <file.png>');
     phantom.exit();
 }
 
+if (system.args.length === 1) {
+    usage();
+}
+
+if (!file_png.match(/\.png$/)) {
+    usage("File name has no .png extension: '" + file_png + "'");
+}
+
+
 // page.zoomFactor = 1.0;
 page.viewportSize = {
     width: system.args[3] ? system.args[3] : 1200,
@@ -28,3 +40,5 @@ page.open(url, function () {
         phantom.exit();
     }, timeout * 1000);
 });
+
+// EOF