CLI: add error handling for latest_version helper

lib/cli/lib/latest_version.js

@@ -1,17 +1,40 @@
-import { sync as spawnSync } from 'cross-spawn';
+import { spawn } from 'cross-spawn';
 import hasYarn from './has_yarn';
 
 const packageManager = hasYarn() ? 'yarn' : 'npm';
 
-export default async function latestVersion(packageName) {
-  const result = spawnSync(packageManager, ['info', packageName, '--json'], {
-    cwd: process.cwd(),
-    env: process.env,
-    stdio: 'pipe',
-    encoding: 'utf-8',
-    silent: true,
-  });
+export default function latestVersion(packageName) {
+  return new Promise((resolve, reject) => {
+    const command = spawn(packageManager, ['info', packageName, 'version', '--json', '--silent'], {
+      cwd: process.cwd(),
+      env: process.env,
+      stdio: 'pipe',
+      encoding: 'utf-8',
+      silent: true,
+    });
 
-  const info = JSON.parse(result.output[1].toString());
-  return info.data.version;
+    command.stdout.on('data', data => {
+      try {
+        const info = JSON.parse(data);
+        if (info.error) {
+          // npm error
+          reject(new Error(info.error.summary));
+        } else if (info.type === 'inspect') {
+          // yarn success
+          resolve(info.data);
+        } else {
+          // npm success
+          resolve(info);
+        }
+      } catch (e) {
+        // yarn info output
+      }
+    });
+
+    command.stderr.on('data', data => {
+      // yarn error
+      const info = JSON.parse(data);
+      reject(new Error(info.data));
+    });
+  });
 }

lib/cli/test/run_tests.sh

@@ -62,12 +62,12 @@ cd ..
 if [ $update -eq 1 ]
   then
     # copy `run` directory contents to `snapshots`, skipping irrelevant files
-    rsync -r --exclude={node_modules**,.DS_Store,*.md} run/ snapshots
+    rsync -r --exclude={node_modules**,.DS_Store,*.md,yarn-error.log} run/ snapshots
   else if [ $skip -eq 0 ]
     then
       # check if there is any difference between `run` and `snapshots` directories,
       # skipping irrelevant files
-      declare diff=`diff -r -x node_modules** -x .DS_Store -x *.md run snapshots`
+      declare diff=`diff -r -x node_modules** -x .DS_Store -x *.md -x yarn-error.log run snapshots`
       if [[ $diff ]]
       then
         # if there is some diff, output it to stderr along with a clarifying message