fix(app): report a crash instead of vanishing, and cap the log

tests/unit/uplink/log.test.tsadded+127-0

Changes to tests/unit/uplink/log.test.ts

		@@ -0,0 +1,127 @@
	1	+import { afterEach, describe, expect, it } from 'bun:test'
	2	+import { appendFileSync, existsSync, mkdtempSync, readFileSync, rmSync, statSync } from 'node:fs'
	3	+import { tmpdir } from 'node:os'
	4	+import { join } from 'node:path'
	5	+import process from 'node:process'
	6	+import { describeFatal, rotate, writeLog } from '../../../app/Uplink/log'
	7	+
	8	+const dirs: string[] = []
	9	+function tempLog(): string {
	10	+ const dir = mkdtempSync(join(tmpdir(), 'uplink-log-'))
	11	+ dirs.push(dir)
	12	+ return join(dir, 'Uplink.log')
	13	+}
	14	+afterEach(() => {
	15	+ for (const dir of dirs.splice(0))
	16	+ rmSync(dir, { recursive: true, force: true })
	17	+})
	18	+
	19	+describe('the log file', () => {
	20	+ it('writes a timestamped line', () => {
	21	+ const path = tempLog()
	22	+ writeLog('hello', path)
	23	+ expect(readFileSync(path, 'utf8')).toMatch(/^\d{4}-\d{2}-\d{2}T[\d:.]+Z hello\n$/)
	24	+ })
	25	+
	26	+ it('makes the directory rather than failing on a first run', () => {
	27	+ const path = join(tempLog(), '..', 'nested', 'Uplink.log')
	28	+ writeLog('first', path)
	29	+ expect(readFileSync(path, 'utf8')).toContain('first')
	30	+ })
	31	+
	32	+ /**
	33	+ * The lines leading up to a crash are the ones worth reading, and a rotation
	34	+ * triggered by that crash's own output would otherwise throw them away. So
	35	+ * one generation is kept rather than truncated.
	36	+ */
	37	+ it('rotates once past the limit and keeps the previous contents', () => {
	38	+ const path = tempLog()
	39	+ appendFileSync(path, 'x'.repeat(2048))
	40	+ rotate(path, 1024)
	41	+
	42	+ expect(existsSync(path)).toBe(false)
	43	+ expect(readFileSync(`${path}.1`, 'utf8')).toHaveLength(2048)
	44	+
	45	+ // And it keeps logging afterwards.
	46	+ writeLog('after the rotation', path, 1024)
	47	+ expect(readFileSync(path, 'utf8')).toContain('after the rotation')
	48	+ expect(statSync(path).size).toBeLessThan(1024)
	49	+ })
	50	+
	51	+ it('leaves a file that is under the limit alone', () => {
	52	+ const path = tempLog()
	53	+ appendFileSync(path, 'small')
	54	+ rotate(path, 1024)
	55	+ expect(readFileSync(path, 'utf8')).toBe('small')
	56	+ expect(existsSync(`${path}.1`)).toBe(false)
	57	+ })
	58	+
	59	+ it('replaces an older rotation rather than accumulating them', () => {
	60	+ const path = tempLog()
	61	+ appendFileSync(`${path}.1`, 'the generation before last')
	62	+ appendFileSync(path, 'y'.repeat(2048))
	63	+ rotate(path, 1024)
	64	+ expect(readFileSync(`${path}.1`, 'utf8')).toHaveLength(2048)
	65	+ expect(existsSync(`${path}.2`)).toBe(false)
	66	+ })
	67	+
	68	+ it('does not throw when the log cannot be written', () => {
	69	+ // A path whose parent is a file, so both mkdir and append fail.
	70	+ const blocked = tempLog()
	71	+ appendFileSync(blocked, 'i am a file')
	72	+ expect(() => writeLog('into the void', join(blocked, 'Uplink.log'))).not.toThrow()
	73	+ })
	74	+})
	75	+
	76	+describe('describeFatal', () => {
	77	+ it('gives the name, message and stack', () => {
	78	+ const described = describeFatal(new TypeError('null is not an object'))
	79	+ expect(described).toContain('TypeError: null is not an object')
	80	+ expect(described).toContain('log.test.ts')
	81	+ })
	82	+
	83	+ it('handles something thrown that is not an Error', () => {
	84	+ expect(describeFatal('just a string')).toBe('just a string')
	85	+ expect(describeFatal(undefined)).toBe('undefined')
	86	+ })
	87	+})
	88	+
	89	+/**
	90	+ * The failure this exists for. An uncaught throw used to go to a stderr the
	91	+ * LaunchAgent does not capture, and the process vanished with the log's last
	92	+ * line being whatever succeeded before it.
	93	+ */
	94	+describe('crash handlers', () => {
	95	+ function crash(how: string): { exitCode: number, log: string } {
	96	+ const path = tempLog()
	97	+ const root = join(import.meta.dir, '..', '..', '..')
	98	+ const result = Bun.spawnSync(['bun', '-e', `
	99	+ import { installCrashHandlers } from ${JSON.stringify(join(root, 'app/Uplink/log.ts'))}
	100	+ installCrashHandlers({ path: ${JSON.stringify(path)} })
	101	+ ${how}
	102	+ `], { stderr: 'pipe', stdout: 'pipe', env: { ...process.env } })
	103	+ return { exitCode: result.exitCode, log: existsSync(path) ? readFileSync(path, 'utf8') : '' }
	104	+ }
	105	+
	106	+ it('records an uncaught throw and exits non-zero', () => {
	107	+ const { exitCode, log } = crash(`setTimeout(() => { throw new Error('boom') }, 0)`)
	108	+ expect(exitCode).toBe(1)
	109	+ expect(log).toContain('uncaught exception')
	110	+ expect(log).toContain('Error: boom')
	111	+ // The stack, which is the part worth having.
	112	+ expect(log).toContain('at ')
	113	+ })
	114	+
	115	+ it('records a rejected promise with no catch', () => {
	116	+ const { exitCode, log } = crash(`Promise.reject(new Error('nobody caught me'))`)
	117	+ expect(exitCode).toBe(1)
	118	+ expect(log).toContain('unhandled rejection')
	119	+ expect(log).toContain('nobody caught me')
	120	+ })
	121	+
	122	+ it('reports one crash, not a cascade', () => {
	123	+ const { log } = crash(`setTimeout(() => { throw new Error('first') }, 0); setTimeout(() => { throw new Error('second') }, 1)`)
	124	+ expect(log).toContain('first')
	125	+ expect(log).not.toContain('second')
	126	+ })
	127	+})