feat(anki): mirror mpv software volume into generated sentence audio (#155)

src/anki-integration/mpv-volume.test.ts

@@ -0,0 +1,56 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+
+import { resolveMpvVolumeScale } from './mpv-volume';
+
+test('resolveMpvVolumeScale converts numeric mpv volume with mpv software volume curve', async () => {
+  const requested: string[] = [];
+
+  const scale = await resolveMpvVolumeScale(
+    {
+      requestProperty: async (name) => {
+        requested.push(name);
+        return 75;
+      },
+    },
+    true,
+  );
+
+  assert.equal(scale, 0.421875);
+  assert.deepEqual(requested, ['volume']);
+});
+
+test('resolveMpvVolumeScale skips mpv when mirroring is disabled', async () => {
+  let requested = false;
+
+  const scale = await resolveMpvVolumeScale(
+    {
+      requestProperty: async () => {
+        requested = true;
+        return 50;
+      },
+    },
+    false,
+  );
+
+  assert.equal(scale, undefined);
+  assert.equal(requested, false);
+});
+
+test('resolveMpvVolumeScale falls back to unity for missing, failed, or invalid values', async () => {
+  assert.equal(await resolveMpvVolumeScale({}, true), 1);
+  assert.equal(
+    await resolveMpvVolumeScale(
+      {
+        requestProperty: async () => {
+          throw new Error('disconnected');
+        },
+      },
+      true,
+    ),
+    1,
+  );
+  assert.equal(await resolveMpvVolumeScale({ requestProperty: async () => '50' }, true), 1);
+  assert.equal(await resolveMpvVolumeScale({ requestProperty: async () => Number.NaN }, true), 1);
+  assert.equal(await resolveMpvVolumeScale({ requestProperty: async () => -1 }, true), 1);
+});