feat: improve serialization of system log input

packages/build/src/log/logger.js

@@ -113,11 +113,21 @@ export const logWarningSubHeader = function (logs, string, opts) {
 const reduceLogLines = function (lines) {
   return lines
     .map((input) => {
+      if (input instanceof Error) {
+        return `${input.message} ${input.stack}`
+      }
+
       if (typeof input === 'object') {
-        return JSON.stringify(input)
+        try {
+          return JSON.stringify(input)
+        } catch {
+          // Value could not be serialized to JSON, so we return the string
+          // representation.
+          return String(input)
+        }
       }
 
-      return input.toString()
+      return String(input)
     })
     .join(' ')
 }

packages/build/tests/unit/logger/snapshots/tests.js.md

@@ -0,0 +1,20 @@
+# Snapshot report for `packages/build/tests/unit/logger/tests.js`
+
+The actual snapshot is saved in `tests.js.snap`.
+
+Generated by [AVA](https://avajs.dev).
+
+## System logger writes to file descriptor
+
+> Snapshot 1
+
+    `Hello world {"object":true,"problem":false} Something went wrong Error: Something went wrong␊
+    STACK TRACE␊
+    `
+
+## System logger does not write to file descriptor when `debug: true`
+
+> Snapshot 1
+
+    `Hello world {"object":true,"problem":false} Something went wrong Error: Something went wrong␊
+    STACK TRACE`

packages/build/tests/unit/logger/tests.js

@@ -4,17 +4,21 @@ import test from 'ava'
 import tmp from 'tmp-promise'
 
 import { getSystemLogger } from '../../../src/log/logger.js'
+import { normalizeOutput } from '../../helpers/normalize.js'
 
 test('System logger writes to file descriptor', async (t) => {
   const { fd, cleanup, path } = await tmp.file()
   const mockProcess = {
     stdout: [],
   }
   const systemLog = getSystemLogger(mockProcess, false, fd)
+  const error = new Error('Something went wrong')
 
-  systemLog('Hello world', { object: true, problem: false })
+  systemLog('Hello world', { object: true, problem: false }, error)
 
-  t.is(await fs.readFile(path, 'utf8'), 'Hello world {"object":true,"problem":false}\n')
+  const output = normalizeOutput(await fs.readFile(path, 'utf8'))
+
+  t.snapshot(output)
   t.is(mockProcess.stdout.length, 0)
 
   await cleanup()
@@ -26,11 +30,14 @@ test('System logger does not write to file descriptor when `debug: true`', async
     stdout: [],
   }
   const systemLog = getSystemLogger(mockProcess, true, fd)
+  const error = new Error('Something went wrong')
+
+  systemLog('Hello world', { object: true, problem: false }, error)
 
-  systemLog('Hello world', { object: true, problem: false })
+  const output = normalizeOutput(mockProcess.stdout[0])
 
   t.is(mockProcess.stdout.length, 1)
-  t.is(mockProcess.stdout[0], 'Hello world {"object":true,"problem":false}')
+  t.snapshot(output)
   t.is(await fs.readFile(path, 'utf8'), '')
 
   await cleanup()