Fetch snowplow contexts for the named experiments

app/assets/javascripts/experimentation/utils.js

 // This file only applies to use of experiments through https://gitlab.com/gitlab-org/gitlab-experiment
 import { get } from 'lodash';
-import { DEFAULT_VARIANT, CANDIDATE_VARIANT } from './constants';
+import { DEFAULT_VARIANT, CANDIDATE_VARIANT, TRACKING_CONTEXT_SCHEMA } from './constants';
 
 export function getExperimentData(experimentName) {
   return get(window, ['gon', 'experiment', experimentName]);
 }
 
+export function getExperimentContexts(...experimentNames) {
+  return experimentNames
+    .map((name) => {
+      const data = getExperimentData(name);
+      return data && { schema: TRACKING_CONTEXT_SCHEMA, data };
+    })
+    .filter((context) => context);
+}
+
 export function isExperimentVariant(experimentName, variantName) {
   return getExperimentData(experimentName)?.variant === variantName;
 }

spec/frontend/experimentation/utils_spec.js

 import { assignGitlabExperiment } from 'helpers/experimentation_helper';
-import { DEFAULT_VARIANT, CANDIDATE_VARIANT } from '~/experimentation/constants';
+import {
+  DEFAULT_VARIANT,
+  CANDIDATE_VARIANT,
+  TRACKING_CONTEXT_SCHEMA,
+} from '~/experimentation/constants';
 import * as experimentUtils from '~/experimentation/utils';
 
 describe('experiment Utilities', () => {
@@ -19,6 +23,20 @@ describe('experiment Utilities', () => {
     });
   });
 
+  describe('getExperimentContexts', () => {
+    describe.each`
+      gon                     | input         | output
+      ${[TEST_KEY, '_data_']} | ${[TEST_KEY]} | ${[{ schema: TRACKING_CONTEXT_SCHEMA, data: { variant: '_data_' } }]}
+      ${[]}                   | ${[TEST_KEY]} | ${[]}
+    `('with input=$input and gon=$gon', ({ gon, input, output }) => {
+      assignGitlabExperiment(...gon);
+
+      it(`returns ${output}`, () => {
+        expect(experimentUtils.getExperimentContexts(...input)).toEqual(output);
+      });
+    });
+  });
+
   describe('isExperimentVariant', () => {
     describe.each`
       gon                            | input                            | output