From a838e6392a407bfffe5bc2db496b414ff1fe0d17 Mon Sep 17 00:00:00 2001
From: Spencer <email@spalger.com>
Date: Tue, 18 Feb 2020 10:57:15 -0700
Subject: [PATCH] [@kbn/optimizer] prevent error when all bundles are cached
 (#57871)

---
 .../basic_optimization.test.ts                | 33 +++++++++++++++++--
 .../optimizer/handle_optimizer_completion.ts  |  5 +++
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/packages/kbn-optimizer/src/integration_tests/basic_optimization.test.ts b/packages/kbn-optimizer/src/integration_tests/basic_optimization.test.ts
index dda818875db2..b35788009dd9 100644
--- a/packages/kbn-optimizer/src/integration_tests/basic_optimization.test.ts
+++ b/packages/kbn-optimizer/src/integration_tests/basic_optimization.test.ts
@@ -33,7 +33,7 @@ const MOCK_REPO_DIR = Path.resolve(TMP_DIR, 'mock_repo');
 
 expect.addSnapshotSerializer(createAbsolutePathSerializer(MOCK_REPO_DIR));
 
-beforeEach(async () => {
+beforeAll(async () => {
   await del(TMP_DIR);
   await cpy('**/*', MOCK_REPO_DIR, {
     cwd: MOCK_REPO_SRC,
@@ -42,7 +42,7 @@ beforeEach(async () => {
   });
 });
 
-afterEach(async () => {
+afterAll(async () => {
   await del(TMP_DIR);
 });
 
@@ -153,3 +153,32 @@ it('builds expected bundles, saves bundle counts to metadata', async () => {
     ]
   `);
 });
+
+it('uses cache on second run and exist cleanly', async () => {
+  const config = OptimizerConfig.create({
+    repoRoot: MOCK_REPO_DIR,
+    pluginScanDirs: [Path.resolve(MOCK_REPO_DIR, 'plugins')],
+    maxWorkerCount: 1,
+  });
+
+  const msgs = await runOptimizer(config)
+    .pipe(
+      tap(state => {
+        if (state.event?.type === 'worker stdio') {
+          // eslint-disable-next-line no-console
+          console.log('worker', state.event.stream, state.event.chunk.toString('utf8'));
+        }
+      }),
+      toArray()
+    )
+    .toPromise();
+
+  expect(msgs.map(m => m.state.phase)).toMatchInlineSnapshot(`
+    Array [
+      "initializing",
+      "initializing",
+      "initializing",
+      "initialized",
+    ]
+  `);
+});
diff --git a/packages/kbn-optimizer/src/optimizer/handle_optimizer_completion.ts b/packages/kbn-optimizer/src/optimizer/handle_optimizer_completion.ts
index fe2fa320818a..9587902cc418 100644
--- a/packages/kbn-optimizer/src/optimizer/handle_optimizer_completion.ts
+++ b/packages/kbn-optimizer/src/optimizer/handle_optimizer_completion.ts
@@ -44,6 +44,11 @@ export function handleOptimizerCompletion(config: OptimizerConfig) {
             return;
           }
 
+          if (prevState?.phase === 'initialized' && prevState.onlineBundles.length === 0) {
+            // all bundles cached
+            return;
+          }
+
           if (prevState?.phase === 'issue') {
             throw createFailError('webpack issue');
           }