feat: ADD Terms of service link (#985)

Adds an optional terms of service link for sites that need it.

---------

Co-authored-by: Jonathan Perret <j-github@jonathanperret.net>

test/nbrowser/TermsOfService.ts

@@ -0,0 +1,37 @@
+import { assert, driver } from 'mocha-webdriver';
+import * as gu from 'test/nbrowser/gristUtils';
+import { server, setupTestSuite } from 'test/nbrowser/testUtils';
+import { EnvironmentSnapshot } from 'test/server/testUtils';
+
+describe('Terms of service link', function () {
+  this.timeout(20000);
+  setupTestSuite({samples: true});
+
+  let session: gu.Session;
+  let oldEnv: EnvironmentSnapshot;
+
+  before(async function () {
+    oldEnv = new EnvironmentSnapshot();
+    session = await gu.session().teamSite.login();
+  });
+
+  after(async function () {
+    oldEnv.restore();
+    await server.restart();
+  });
+
+  it('is visible in home menu', async function () {
+    process.env.GRIST_TERMS_OF_SERVICE_URL = 'https://example.com/tos';
+    await server.restart();
+    await session.loadDocMenu('/');
+    assert.isTrue(await driver.find('.test-dm-tos').isDisplayed());
+    assert.equal(await driver.find('.test-dm-tos').getAttribute('href'), 'https://example.com/tos');
+  });
+
+  it('is not visible when environment variable is not set', async function () {
+    delete process.env.GRIST_TERMS_OF_SERVICE_URL;
+    await server.restart();
+    await session.loadDocMenu('/');
+    assert.isFalse(await driver.find('.test-dm-tos').isPresent());
+  });
+});