Add deep-playthrough and turn-loop crash-sweep tests (playtest hardening)

Two death-safe regression drives that exercise the full turn loop within the
step-8 os.Exit constraint (a fortify() helper pins HP/food/exp and clears the
freeze/stuck counters each turn, so no death exits the test binary; fixed seeds
keep them deterministic):

- TestDeepPlaythrough: quaff/read/zap through command dispatch, then descend the
  staircase to depth 8 with a save/restore at depth 4 — a crash sweep of deep
  level generation, item effects, and mid-game save/restore. It asserts the
  consumables identify themselves (the commands really ran) and the descent and
  restore land where expected.
- TestTurnLoopCrashSweep: mash movement/search/rest for 200 turns on four seeds,
  exercising combat, monster AI, and traps.

Neither surfaced a panic. Space-separated command scripts answer the --More--
prompts, as wait_for consumes input up to a space.

game/run_test.go

@@ -1,10 +1,25 @@
 package game
 
 import (
+	"path/filepath"
 	"strings"
 	"testing"
 )
 
+// fortify makes the hero effectively immortal for a crash-sweep drive:
+// game-over now calls myExit and os.Exit(0) (step 8), which would kill the
+// test binary, so every death vector is neutralized. Re-applied each turn
+// because combat, digestion, freezing, and level drain chip away at these.
+func fortify(g *RogueGame) {
+	p := &g.Player
+	p.Stats.HP = 30000    // survive combat, arrow/dart traps, bolts
+	p.Stats.MaxHP = 30000 // survive vampire max-hp drain
+	p.Stats.Exp = 30000   // survive wraith level drain (death when exp hits 0)
+	p.FoodLeft = 30000    // never starve
+	g.NoCommand = 0       // never freeze to death (ice monster / sleep trap)
+	g.NoMove = 0          // never stay stuck in a bear trap
+}
+
 // driveTurns runs the game's per-turn loop up to n times, doing the same
 // first-level and pre-play setup Run() does. Run() itself no longer
 // returns — game-over exits the process — so tests drive command()
@@ -67,3 +82,123 @@ func TestScoreRendersList(t *testing.T) {
 		t.Error("score list not on screen")
 	}
 }
+
+// TestDeepPlaythrough drives a fortified hero through the real command loop:
+// quaff/read/zap on the first level, then descend through the staircase to
+// depth 8, saving and restoring mid-way. It is a crash sweep of the turn
+// engine, deep level generation, item effects, and mid-game save/restore.
+// The hero is fortified so no death exits the process (step 8), and the fixed
+// seed keeps it deterministic.
+func TestDeepPlaythrough(t *testing.T) {
+	g := New(Params{Seed: 4242, Wizard: true, Term: &testTerm{}})
+	g.startLevel()
+	g.prePlay()
+	fortify(g)
+
+	// Stock and use one of each consumable through the command dispatch.
+	pot := give(g, &Object{Kind: KindPotion, Which: int(PotionHealing)})
+	scr := give(g, &Object{Kind: KindScroll, Which: int(ScrollMagicMapping)})
+
+	wand := newObject()
+	wand.Kind = KindWand
+	wand.Which = int(WandLight)
+	wand.Charges = 5
+	zap := give(g, wand)
+
+	setInput(t, g, 'q', pot) // quaff healing
+	g.command()
+	setInput(t, g, 'r', scr) // read magic mapping
+	g.command()
+	setInput(t, g, 'z', 'h', zap) // zap the light wand west
+	g.command()
+	fortify(g)
+
+	// Each consumable identifies itself on use, confirming the q/r/z
+	// commands actually ran through dispatch (not aborted on a bad prompt).
+	if !g.Items.Potions[PotionHealing].Know {
+		t.Error("quaff command did not identify the healing potion")
+	}
+
+	if !g.Items.Scrolls[ScrollMagicMapping].Know {
+		t.Error("read command did not identify the magic-mapping scroll")
+	}
+
+	if !g.Items.Sticks[WandLight].Know {
+		t.Error("zap command did not identify the light wand")
+	}
+
+	const wantDepth = 8
+
+	for g.Depth < wantDepth {
+		g.Player.Pos = g.Level.Stairs // stand on the stairs
+		setInput(t, g, '>', '.')      // '>' descends (free), '.' pays the turn
+		g.command()
+		fortify(g)
+
+		if g.Depth == 4 {
+			g = saveAndRestore(t, g)
+			fortify(g)
+		}
+	}
+
+	if g.Depth != wantDepth {
+		t.Errorf("depth = %d after descending, want %d", g.Depth, wantDepth)
+	}
+
+	if g.Player.Stats.HP <= 0 {
+		t.Error("hero died during the playthrough")
+	}
+}
+
+// TestTurnLoopCrashSweep mashes movement, search, and rest through the real
+// turn loop for many turns on several seeds, exercising combat, monster AI,
+// and traps. The hero is fortified each turn so nothing exits the process,
+// and the fixed seeds keep it deterministic; the point is to surface panics.
+func TestTurnLoopCrashSweep(t *testing.T) {
+	// A generous mix of movement, search, and rest. The spaces between
+	// commands double as answers to any --More-- prompt (wait_for eats
+	// everything up to a space); without them one prompt would swallow the
+	// rest of the script. The script is long enough that the bounded drive
+	// never exhausts it (which would spin on the auto-fed prompt input).
+	script := []byte(strings.Repeat("h j k l y u b n s . ", 400))
+
+	for _, seed := range []int32{1, 99, 2026, 31337} {
+		g := New(Params{Seed: seed, Term: &testTerm{input: script}})
+		g.startLevel()
+		g.prePlay()
+
+		for range 200 {
+			fortify(g)
+			g.command()
+		}
+
+		if g.Player.Stats.HP <= 0 {
+			t.Errorf("seed %d: hero died despite fortify", seed)
+		}
+	}
+}
+
+// saveAndRestore snapshots the game to a file, restores it, checks the key
+// state survived, and returns the restored game ready to keep playing.
+func saveAndRestore(t *testing.T, g *RogueGame) *RogueGame {
+	t.Helper()
+
+	path := filepath.Join(t.TempDir(), "deep.save")
+
+	saveErr := g.saveFile(path)
+	if saveErr != nil {
+		t.Fatalf("saveFile: %v", saveErr)
+	}
+
+	h, err := Restore(path, Params{Wizard: true, Term: &testTerm{}})
+	if err != nil {
+		t.Fatalf("Restore: %v", err)
+	}
+
+	if h.Depth != g.Depth || h.Player.Purse != g.Player.Purse {
+		t.Errorf("restored game diverged: depth %d/%d purse %d/%d",
+			h.Depth, g.Depth, h.Player.Purse, g.Player.Purse)
+	}
+
+	return h
+}