[preview current] cleanup code and add test

changedetectionio/__init__.py

@@ -877,9 +877,9 @@ def changedetection_app(config=None, datastore_o=None):
             flash("No history found for the specified link, bad link?", "error")
             return redirect(url_for('index'))
 
-        if watch.history_n >0:
+
-            timestamps = sorted(watch.history.keys(), key=lambda x: int(x))
+        timestamp = list(watch.history.keys())[-1]
-            filename = watch.history[timestamps[-1]]
+        filename = watch.history[timestamp]
         try:
             with open(filename, 'r') as f:
                 tmp = f.readlines()
@@ -908,11 +908,9 @@ def changedetection_app(config=None, datastore_o=None):
                         classes.append('triggered')
                     content.append({'line': l, 'classes': ' '.join(classes)})
 
-
         except Exception as e:
             content.append({'line': "File doesnt exist or unable to read file {}".format(filename), 'classes': ''})
-        else:
+
-            content.append({'line': "No history found", 'classes': ''})
 
         screenshot_url = datastore.get_screenshot(uuid)
         system_uses_webdriver = datastore.data['settings']['application']['fetch_backend'] == 'html_webdriver'

changedetectionio/tests/test_backend.py

@@ -90,6 +90,14 @@ def test_check_basic_change_detection_functionality(client, live_server):
     res = client.get(url_for("diff_history_page", uuid="first"))
     assert b'Compare newest' in res.data
 
+    # Check the [preview] pulls the right one
+    res = client.get(
+        url_for("preview_page", uuid="first"),
+        follow_redirects=True
+    )
+    assert b'which has this one new line' in res.data
+    assert b'Which is across multiple lines' not in res.data
+
     time.sleep(2)
 
     # Do this a few times.. ensures we dont accidently set the status