restore comment

Author: max-ostapenko

tests/wpt.js

@@ -137,10 +137,25 @@ ${metricsToLogString}
     customMetrics.forEach(metricName => {
       let wptCustomMetric = firstViewData[`_${metricName}`];
       try {
+        // Some, but not all, custom metrics wrap their return values in JSON.stringify()
+        // Some just return the objects. And some have strings which are not JSON!
+        // Gotta love the consistency!!!
+        //
+        // IMHO wrapping the return in JSON.stringify() is best practice, since WebPageTest
+        // will do that to save to database and you can run into weird edge cases where it
+        // doesn't return data when doing that, so explicitly doing that avoids that when
+        // testing in the console* , but we live in an inconsistent world!
+        // (* see https://github.com/HTTPArchive/custom-metrics/pull/113#issuecomment-2043937823)
+        //
+        // Anyway, if it's a string, see if we can parse it back to a JS object to pretty
+        // print it, but be prepared for that to fail for non-JSON strings so wrap in try/catch
+        // See pipeline: https://github.com/HTTPArchive/data-pipeline/blob/main/modules/import_all.py#L115
         if (typeof wptCustomMetric === 'string') {
           wptCustomMetric = JSON.parse(wptCustomMetric);
         }
-      } catch (e) { }
+      } catch (e) {
+        // If it fails, that's OK as we'll just stick with the exact string output anyway
+      }
       wptCustomMetrics[`_${metricName}`] = wptCustomMetric;
     });