tests/e2e: update jest environment settings

Usage of GO_DISCOVERY_E2E_ENVIRONMENT is updated so that if it is set to
"staging" or "prod", then the staging snapshots are used. Otherwise, the
ci snapshots are used.

A license header is add to tests/e2e/snapshotResolver.js and comments
are added for future readers.

Change-Id: Ib9d0ba2032b27479b3ecab93347fdfb939bd2aee
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/341109
Trust: Julie Qiu <julie@golang.org>
Reviewed-by: Jamal Carvalho <jamal@golang.org>

jest.config.js

@@ -17,11 +17,16 @@ let config = {
   testPathIgnorePatterns: ['tests/e2e'],
 };
 
+// When GO_DISCOVERY_E2E_ENVIRONMENT is not set to staging or prod, use the
+// snapshots in tests/e2e/__snapshots__/ci. Otherwise, use
+// tests/e2e/__snapshots__/staging. Data in staging and prod are always expected
+// to be the same.
+//
 // eslint-disable-next-line no-undef
 const env = process.env.GO_DISCOVERY_E2E_ENVIRONMENT;
-let ignore = 'ci';
-if (env == 'ci') {
-  ignore = 'staging';
+let ignore = 'staging';
+if (env === 'staging' || env === 'prod') {
+  ignore = 'ci';
 }
 
 // eslint-disable-next-line no-undef

tests/e2e/setup.ts

@@ -7,11 +7,18 @@
 
 import { configureToMatchImageSnapshot } from 'jest-image-snapshot';
 
+// When GO_DISCOVERY_E2E_ENVIRONMENT is not set to staging or prod, use the
+// snapshots in tests/e2e/__snapshots__/ci. Otherwise, use
+// tests/e2e/__snapshots__/staging. Data in taging and prod are always expected
+// to be the same.
+//
+// eslint-disable-next-line no-undef
 let env = process.env.GO_DISCOVERY_E2E_ENVIRONMENT;
-if (env != 'ci') {
+if (env === 'staging' || env === 'prod') {
   env = 'staging';
+} else {
+  env = 'ci';
 }
-
 const snapshotDir = `tests/e2e/__image_snapshots__/${env}`;
 
 // Extends jest to compare image snapshots.

tests/e2e/snapshotResolver.js

@@ -1,9 +1,22 @@
+/**
+ * @license
+ * Copyright 2021 The Go Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file.
+ */
+
+// When GO_DISCOVERY_E2E_ENVIRONMENT is not set to staging or prod, use the
+// snapshots in tests/e2e/__snapshots__/ci. Otherwise, use
+// tests/e2e/__snapshots__/staging. Data in staging and prod are always
+// expected to be the same.
+//
 // eslint-disable-next-line no-undef
 let env = process.env.GO_DISCOVERY_E2E_ENVIRONMENT;
-if (env != 'ci') {
+if (env === 'staging' || env === 'prod') {
   env = 'staging';
+} else {
+  env = 'ci';
 }
-
 const snapshotDir = `tests/e2e/__snapshots__/${env}`;
 
 // eslint-disable-next-line no-undef