Fix two intermittently failing library tests (closes #90)

Library.close() now returns a promise that resolves once the work it
started has finished: an in-flight refresh with its cache write, the ML
data fetch, and running precache sweeps. The interval test could see a
refresh's new state, close, and remove the directory while the write was
still running. Every library test and CLI command now awaits close(), and
tests hold each of the three writes open to prove close() waits for it.

The precache test waited for its stub source to be called, but the cache
records a file only after checking it on disk, so status() could lag. It
now waits for both fills to report "done".

Model: opus-5-5

src/cli-commands.ts

@@ -194,7 +194,7 @@ export const collectionsCommand = async (
         }
         return 0;
     } finally {
-        lib.close();
+        await lib.close();
     }
 };
 
@@ -235,7 +235,7 @@ export const filesCommand = async (
         }
         return 0;
     } finally {
-        lib.close();
+        await lib.close();
     }
 };
 
@@ -272,7 +272,7 @@ export const getCommand = async (
         ctx.stderr.write(`${result.bytes} bytes -> ${outPath}\n`);
         return 0;
     } finally {
-        lib.close();
+        await lib.close();
     }
 };
 
@@ -309,7 +309,7 @@ export const getThumbCommand = async (
         ctx.stderr.write(`${result.bytes} bytes -> ${outPath}\n`);
         return 0;
     } finally {
-        lib.close();
+        await lib.close();
     }
 };
 
@@ -329,7 +329,7 @@ export const backupMetadataCommand = async (
         });
         return 0;
     } finally {
-        lib.close();
+        await lib.close();
     }
 };
 
@@ -376,7 +376,7 @@ export const backupCommand = async (
 
         return result.failed > 0 ? 1 : 0;
     } finally {
-        lib.close();
+        await lib.close();
     }
 };
 
@@ -411,7 +411,7 @@ export const listMissingThumbnailsCommand = async (
         }
         return 0;
     } finally {
-        lib.close();
+        await lib.close();
     }
 };
 
@@ -481,6 +481,6 @@ export const fixMissingThumbnailsCommand = async (
 
         return results.some((r) => r.status === "failed") ? 1 : 0;
     } finally {
-        lib.close();
+        await lib.close();
     }
 };

test/library/mldata.test.ts

@@ -446,4 +446,51 @@ describe("Library ML-data fetch on refresh", () => {
             await lib.close();
         }
     });
+
+    it("close() resolves only after a running ML data fetch has stored its payloads", async () => {
+        const client = new MLMockClient();
+        client.collectionsQueue.push({
+            collections: [collection(1, 100)],
+            deleted: [],
+            cursor: 100,
+        });
+        client.filesFor(1, {
+            files: [file(1001, 1, 90)],
+            deleted: [],
+            cursor: 90,
+        });
+        client.mlByFile.set(1001, payload([0.5, 0.25, 0.75]));
+
+        // Hold the ML data fetch open until the test releases it.
+        let release!: () => void;
+        const held = new Promise<void>((r) => (release = r));
+        let fetchStarted!: () => void;
+        const started = new Promise<void>((r) => (fetchStarted = r));
+        const realFetch = client.fetchMLData.bind(client);
+        client.fetchMLData = async (args) => {
+            fetchStarted();
+            await held;
+            return realFetch(args);
+        };
+
+        const lib = await Library.open({
+            client,
+            cacheDirectory,
+            refreshIntervalSeconds: 3600,
+        });
+        await started;
+
+        let closed = false;
+        const closing = lib.close().then(() => {
+            closed = true;
+        });
+        await new Promise((r) => setTimeout(r, 20));
+        expect(closed).toBe(false);
+
+        release();
+        await closing;
+        expect(existsSync(join(cacheDirectory, "mldata", "1001.json"))).toBe(
+            true,
+        );
+    });
 });

test/library/precache.test.ts

@@ -445,4 +445,43 @@ describe("Precache through Library.open", () => {
         expect(status.originalsCached).toBe(3);
         await lib.close();
     });
+
+    it("close() resolves only after a running precache fetch has written its file", async () => {
+        // Every thumbnail fetch waits until the test releases it.
+        let release!: () => void;
+        const held = new Promise<void>((r) => (release = r));
+        let fetchStarted!: (destination: string) => void;
+        const started = new Promise<string>((r) => (fetchStarted = r));
+        const source: ContentSource = {
+            original: async ({ destination }) => {
+                await writeFile(destination, Buffer.alloc(10, 1));
+                return { bytesWritten: 10 };
+            },
+            thumbnail: async ({ destination }) => {
+                fetchStarted(destination);
+                await held;
+                await writeFile(destination, Buffer.alloc(10, 1));
+                return { bytesWritten: 10 };
+            },
+        };
+        const lib = await Library.open({
+            client: new MockClient(),
+            cacheDirectory: join(root, "cache"),
+            contentSource: source,
+            refreshIntervalSeconds: 3600,
+            precacheOriginals: false,
+        });
+        const destination = await started;
+
+        let closed = false;
+        const closing = lib.close().then(() => {
+            closed = true;
+        });
+        await new Promise((r) => setTimeout(r, 20));
+        expect(closed).toBe(false);
+
+        release();
+        await closing;
+        expect(existsSync(destination)).toBe(true);
+    });
 });