build: resolve latest MDC version through yarn

Uses Yarn to resolve the latest canary version of MDC in an attempt to avoid flakes due to mismatches.

Author: crisbeto

scripts/circleci/setup-mdc-canary.js

@@ -1,16 +1,37 @@
 const {join} = require('path');
-const {spawn} = require('child_process');
+const {spawn, spawnSync} = require('child_process');
 const packageJson = require(join(__dirname, '../../package.json'));
+
+// Note that yarn also has a `versions` field, but it appears to be sorting canary versions
+// alphabetically so we can't depend on it. Instead we use `time` which is a version to time map.
+const versionsProcess = spawnSync('yarn', ['info', 'material-components-web', 'time', '--json'], {
+  shell: true
+});
+let versions = null;
+
+try {
+  versions = JSON.parse(versionsProcess.stdout).data;
+} catch (e) {
+  console.error('Failed to retrieve latest MDC version');
+  throw e;
+}
+
+const latestCanaryVersion = Object.keys(versions)
+  .filter(key => key.includes('-canary'))
+  .sort((a, b) => new Date(versions[a]) - new Date(versions[b]))
+  .pop();
+
 const pattern = /^material-components-web$|^@material\//;
 const params = Object.keys(packageJson.devDependencies)
   .filter(dependency => pattern.test(dependency))
-  .reduce((mdcDependencies, dependency) => [...mdcDependencies, `${dependency}@canary`], []);
+  .reduce((mdcDependencies, dependency) =>
+    [...mdcDependencies, `${dependency}@${latestCanaryVersion}`], []);
 
 if (!params.length) {
   throw Error(`Could not find MDC dependencies in package.json`);
 }
 
-console.log('Updating all MDC dependencies to latest canary version');
+console.log(`Updating all MDC dependencies to version ${latestCanaryVersion}`);
 const childProcess = spawn('yarn', ['add', ...params, '-D'], {shell: true});
 childProcess.stdout.on('data', data => console.log(data + ''));
 childProcess.stderr.on('data', data => console.error(data + ''));