Added games: a reused ranking is not remembered as a fresh walk

A ranking a scan took from added-games-scan.json was also put in the
60-second in-memory cache with the current time, so for the next minute
single(), addFolder() and the exe picker, which ask for a fresh walk, got
a ranking that could be a week old. Kept rankings are now returned without
entering that cache, so it only ever holds rankings from real walks.

app/src/main/java/com/droiddeck/launcher/frontend/AddedGames.kt

@@ -103,7 +103,7 @@ object AddedGames {
         val key = "${folder.path}|${folder.lastModified()}"
         val now = System.currentTimeMillis()
         ranked[key]?.takeIf { now - it.first < RANK_FRESH_MS }?.let { return it.second }
-        if (reuse) kept?.rank(folder)?.let { ranked[key] = now to it; return it }
+        if (reuse) kept?.rank(folder)?.let { return it }
         val guessed = GameExePicker.rank(folder) { !skipExe(it.name) }
         val declared = declaredExes(folder)
         val preferred = declared.map { it.path }.toSet()

app/src/test/java/com/droiddeck/launcher/frontend/AddedGamesCacheTest.kt

@@ -111,6 +111,23 @@ class AddedGamesCacheTest {
         assertEquals("Bastion", AddedGamesCache(file).name("named"))
     }
 
+    @Test fun aRankingAScanReusedIsNotHandedToAFreshLookup() {
+        val folder = tmp.newFolder("Game")
+        val walked = File(folder, "Game.exe").apply { writeText("game") }
+        val kept = File(folder, "Other.exe").apply { writeText("other") }
+        val files = tmp.newFolder("files")
+        val context = object : android.content.ContextWrapper(app) {
+            override fun getFilesDir() = files
+        }
+        AddedGamesCache(File(files, AddedGamesCache.FILE)).apply {
+            keepRank(folder, GameExePicker.Ranking(listOf(kept), listOf(10), false))
+            save()
+        }
+        AddedGames.scan(context)
+        assertEquals(listOf(kept), AddedGames.rank(folder, reuse = true).exes)
+        assertEquals(walked, AddedGames.candidates(folder).first())
+    }
+
     @Test fun aScanKeepsEachGamesRankingForTheNextLaunch() {
         val (folder, exe) = game("Card Game")
         AddedExes.put(app, AddedExes.Entry(folder.path, exe.path, picked = false))