fix: flaky apps:diff tests (#3649)

resolve slug checksums sequentially and drop unused app2 nock mocks in 404 tests to stop flaky unit failures

Author: michaelmalave

src/commands/apps/diff.ts

@@ -45,8 +45,9 @@ async function checksum(heroku: APIClient, app: string): Promise<string | null>
 }
 
 async function diffFiles(heroku: APIClient, app1: string, app2: string): Promise<DiffRow[]> {
-  const sums = await Promise.all([checksum(heroku, app1), checksum(heroku, app2)])
-  return sums[0] === sums[1] ? [] : [{prop: 'slug (checksum)', app1: sums[0] ?? undefined, app2: sums[1] ?? undefined}]
+  const sum1 = await checksum(heroku, app1)
+  const sum2 = await checksum(heroku, app2)
+  return sum1 === sum2 ? [] : [{prop: 'slug (checksum)', app1: sum1 ?? undefined, app2: sum2 ?? undefined}]
 }
 
 async function diffEnv(heroku: APIClient, app1: string, app2: string): Promise<DiffRow[]> {

test/unit/commands/apps/diff.unit.test.ts

@@ -132,8 +132,6 @@ describe('apps:diff', function () {
   it('throws App not found when one app returns 404 on releases', async function () {
     api
       .get(`/apps/${app1Name}/releases`).matchHeader('range', /version/).reply(404, {id: 'not_found', message: 'Couldn\'t find that app.'})
-      .get(`/apps/${app2Name}/releases`).matchHeader('range', /version/).reply(200, releasesWithSlug(slugId2))
-      .get(`/apps/${app2Name}/slugs/${slugId2}`).optionally().reply(200, slugBody(sameChecksum))
 
     const {error} = await runCommand(AppsDiff, [app1Name, app2Name])
 
@@ -146,8 +144,6 @@ describe('apps:diff', function () {
     api
       .get(`/apps/${app1Name}/releases`).matchHeader('range', /version/).reply(200, releasesWithSlug(slugId1))
       .get(`/apps/${app1Name}/slugs/${slugId1}`).reply(404, {id: 'not_found', message: 'Not found'})
-      .get(`/apps/${app2Name}/releases`).matchHeader('range', /version/).reply(200, releasesWithSlug(slugId2))
-      .get(`/apps/${app2Name}/slugs/${slugId2}`).reply(200, slugBody(sameChecksum))
 
     const {error} = await runCommand(AppsDiff, [app1Name, app2Name])