MWPW-159555 Add support for lana-sample query param (#3045)

* MWPW-159555 Add support for lana-sample query param

The `lana-sample` query param will override any sample rate defined elsewhere.  Setting it to "100" will force lana to send everything to splunk.

* Disable es-lint on lana.js

* Use explicit eslint labels

* Fix lana test to not intermittently fail

* Add invalid value test

libs/utils/lana.js

@@ -1,4 +1,6 @@
-(function () {
+/* eslint-disable no-param-reassign */
+/* eslint-disable no-console */
+(function iife() {
   const MSG_LIMIT = 2000;
 
   const defaultOptions = {
@@ -49,10 +51,6 @@
     }, {});
   }
 
-  function sendUnhandledError(e) {
-    log(e.reason || e.error || e.message, { errorType: 'i' });
-  }
-
   function log(msg, options) {
     msg = msg && msg.stack ? msg.stack : (msg || '');
     if (msg.length > MSG_LIMIT) {
@@ -65,7 +63,8 @@
       return;
     }
 
-    const sampleRate = o.errorType === 'i' ? o.implicitSampleRate : o.sampleRate;
+    const sampleRateParam = parseInt(new URL(window.location).searchParams.get('lana-sample'), 10);
+    const sampleRate = sampleRateParam || (o.errorType === 'i' ? o.implicitSampleRate : o.sampleRate);
 
     if (!w.lana.debug && !w.lana.localhost && sampleRate <= Math.random() * 100) return;
 
@@ -95,10 +94,15 @@
       }
       xhr.open('GET', `${endpoint}?${queryParams.join('&')}`);
       xhr.send();
+      // eslint-disable-next-line consistent-return
       return xhr;
     }
   }
 
+  function sendUnhandledError(e) {
+    log(e.reason || e.error || e.message, { errorType: 'i' });
+  }
+
   function hasDebugParam() {
     return w.location.search.toLowerCase().indexOf('lanadebug') !== -1;
   }

libs/utils/lana.md

@@ -37,6 +37,7 @@ Note that any errors that happen on a `*.corp.adobe.com` domain will automatical
         * same as `sampleRate`
     * `useProd` - bool: Defaults to `true`
         * Toggle between prod and stage endpoints
+
 ## Helper Functions
 
 The helper functions have been deprecated in favor of the options being passed with every lana call.
@@ -52,6 +53,8 @@ Note that the default option state is stored in `window.lana.options` and can be
 Debugging mode can be enabled by setting a `lanaDebug` query param.  This sends lana messages with debug enabled and will console.log the responses.
 Alternatively, the `window.lana.debug` property can be set (the query param also sets this property).
 
+The Lana logging sample rate can be overridden with the `lana-sample` query param.  It should be set as an integer between 0-100.  This will set the sample rate for all lana messages regardless of other sample rates set.
+
 ## localhost
 
 When on a url that contains "localhost", logged messages will not be sent to the server and will be displayed in the console.  However if debug is enabled, then messages will be sent.

test/utils/lana.test.js

@@ -170,4 +170,55 @@ describe('LANA', () => {
       'https://www.stage.adobe.com/lana/ll?m=only%20the%20clientId%20set%20in%20window.lana.options&c=blah&s=100&t=e',
     );
   });
+
+  it('The lana-sample query param overrides existing sampleRate', () => {
+    window.lana.options = {
+      clientId: 'blah',
+      sampleRate: 0,
+      implicitSampleRate: 0,
+    };
+    const originalUrl = window.location.href;
+
+    window.lana.log('Sample rate is zero so should not be logged');
+    expect(xhrRequests.length).to.equal(0);
+
+    // create a new url based on the current url that adds a query param for lana-sample
+    const newUrl = new URL(window.location.href);
+    newUrl.searchParams.set('lana-sample', '100');
+
+    window.history.pushState({ path: newUrl.toString() }, '', newUrl.toString());
+
+    window.lana.log('lana-sample query param');
+    expect(xhrRequests.length).to.equal(1);
+    expect(xhrRequests[0].method).to.equal('GET');
+    expect(xhrRequests[0].url).to.equal(
+      'https://www.stage.adobe.com/lana/ll?m=lana-sample%20query%20param&c=blah&s=100&t=e',
+    );
+
+    window.history.pushState({ path: originalUrl }, '', originalUrl);
+  });
+
+  it('Invalid lana-sample query params are ignored', () => {
+    window.lana.options = {
+      clientId: 'blah',
+      sampleRate: 100,
+      implicitSampleRate: 100,
+    };
+    const originalUrl = window.location.href;
+
+    // create a new url based on the current url that adds a query param for lana-sample
+    const newUrl = new URL(window.location.href);
+    newUrl.searchParams.set('lana-sample', 'notvalid');
+
+    window.history.pushState({ path: newUrl.toString() }, '', newUrl.toString());
+
+    window.lana.log('lana-sample query param');
+    expect(xhrRequests.length).to.equal(1);
+    expect(xhrRequests[0].method).to.equal('GET');
+    expect(xhrRequests[0].url).to.equal(
+      'https://www.stage.adobe.com/lana/ll?m=lana-sample%20query%20param&c=blah&s=100&t=e',
+    );
+
+    window.history.pushState({ path: originalUrl }, '', originalUrl);
+  });
 });