Merge test/rings-coverage (ring tests verified against C)

This commit was merged in pull request #34.
This commit is contained in:
2026-08-09 17:08:28 +02:00
2 changed files with 820 additions and 2 deletions

71
TODO.md
View File

@@ -29,11 +29,78 @@ Refactor ground rules:
# Next Step
Broaden unit test coverage where playtesting finds thin spots (rings, sticks,
wizard commands).
Broaden unit test coverage where playtesting finds thin spots — sticks (#6) and
wizard commands (#7). Rings, the first third of this step, is done; see the top
of Completed Steps.
# Completed Steps
- 2026-08-09 Ring unit-test coverage (`test/rings-coverage`, closes #5): the
first third of the standing coverage step. `game/rings.go` had **zero** tests
— not one of the 32 in the suite touched wear, removal, hand choice, or the
ring contribution to the hunger clock. New `game/rings_test.go` (17 tests, 44
subtests) covers `ringOn`, `pickRingHand`, `ringOff`, `gethand`, `ringEat` and
`ringNum`, plus the ring arm of `things.c dropcheck` (`dropRing`), which is
what actually takes a ring off. Package coverage 53.7% -> 56.2%. `Next Step`
narrowed rather than rotated: #6 and #7 are the other two thirds.
Every expected value is transcribed from `origin/c-master` (`rings.c`,
`rogue.h`, `things.c`), never from what the port returns, and the C is
quoted in the file. **No divergence from C was found**, which is the result
and is worth recording as a negative: `ringEat` is the one function here
whose being wrong would be invisible — it feeds `daemons.c`'s hunger clock,
so a bad entry is a slow drift in when the hero starves rather than anything
a playtest would notice — and it now has all fourteen ring kinds pinned to
C's table.
Three C details the tests were written around. (1) `ring_eat`'s `uses[]`
holds negatives, and a negative is **not** a cost: C computes
`eat = (rnd(-eat) == 0)`, a one-in-n chance of a single unit. (2) `R_DIGEST`
then flips the sign, so slow digestion returns 0 or **-1** and is the only
ring that gives food back. (3) `ring_num`'s switch closes with the
`otherwise` macro, which `rogue.h` 53 defines as `break;default` — so its
four labels fall through to one `sprintf` and every other kind returns `""`
from a default arm, not by falling off the end. The `RingKind` iota matches
C's `R_` numbering index-for-index, so a `uses[]` index and a `RingKind` are
the same number; `R_ADDHIT` is `RingDexterity` and `R_ADDDAM` is
`RingIncreaseDamage`.
The chance rings are checked two ways at once. Each call snapshots the
generator, runs `ringEat`, and replays C's own expression from the identical
state — which pins the one-in-n denominator, the sign flip, and the fact
that exactly one `rnd` call is spent — and a frequency check over 4000
trials backs it with a number a human can read. The non-negative entries
assert the reverse: the generator must be **untouched**, because C never
reaches `rnd` on that path and a stray call there would desynchronise the
whole game's RNG stream from C's and cost seed compatibility. That assertion
is what caught the one real bug in this work, which was in the test and not
the game: `g.Rng` is a pointer, so the first draft's snapshots aliased
instead of copying.
Two shapes worth keeping. Scripted hand answers carry an abort tail (a space
for the reprompt's `--More--`, then ESCAPE): without it a port that stopped
accepting a key would loop forever on the headless terminal's filler input
and the test would die of the 30s timeout instead of failing on its
assertion — which is exactly what the first draft did, and it was only
visible because the mutation run was inspected rather than trusted. And the
"only one hand free" case scripts the _wrong_ hand key deliberately: a port
that asked anyway consumes it and lands the ring on the wrong side, so the
test fails on a hand rather than on a hang.
Mutation-proved, 23 mutations, each reverted: breaking `pickRingHand`'s
ask/auto/reject arms, `ring_on`'s type guard, `is_current` guard and all
three effect arms, `ring_off`'s no-rings message, hand selection and ESCAPE
abort, `gethand`'s uppercase keys, ESCAPE and reprompt, `dropRing`'s hand
clearing and both effect arms, `dropcheck`'s cursed gate, three `ringUses`
entries, the `R_DIGEST` sign flip, the one-in-n roll, the empty-hand zero,
and `ring_num`'s `ISKNOW` guard, label set and `RING`-vs-`WEAPON`
formatting. Each failed its own test and only its own; stripping all three
`ring_on` effect arms failed 3 of 3. All fourteen ring kinds are exercised;
the eleven with no wear-time effect in C are documented at the foot of the
file as deliberately not given a wear/remove test, with the files their
powers actually live in, and `ring_off`'s unreachable "not wearing such a
ring" arm is documented as unreachable rather than left looking untested.
- 2026-08-09 Command dispatch audit (`audit/command-switch-coverage`, closes
#31): checked every case label in C's `command.c` against this port's
dispatch, and left the audit behind as a standing test

751
game/rings_test.go Normal file
View File

@@ -0,0 +1,751 @@
//nolint:testpackage // white-box tests reach unexported state (approved 2026-07-07)
package game
import (
"fmt"
"math"
"testing"
)
// rings_test.go covers rings.c — ring_on, gethand, ring_off, ring_eat and
// ring_num — plus the ring arm of things.c dropcheck (dropRing), which is
// what actually takes a worn ring off.
//
// Every expected value below is transcribed from the C reference on the
// origin/c-master branch (rings.c, rogue.h, things.c), not from what this
// port happens to return. A test that asserts the current Go behaviour
// cannot catch the port drifting away from C, which is the only thing
// these tests exist to do.
//
// The C constants in play (rogue.h 122-123 and 275-289):
//
// #define LEFT 0 #define RIGHT 1
// R_PROTECT 0 R_ADDSTR 1 R_SUSTSTR 2 R_SEARCH 3
// R_SEEINVIS 4 R_NOP 5 R_AGGR 6 R_ADDHIT 7
// R_ADDDAM 8 R_REGEN 9 R_DIGEST 10 R_TELEPORT 11
// R_STEALTH 12 R_SUSTARM 13 MAXRINGS 14
//
// The Go RingKind iota (types.go 303-316) runs in that same order, so a C
// uses[] index and a Go RingKind are the same number. R_ADDHIT is the
// dexterity ring (RingDexterity) and R_ADDDAM is RingIncreaseDamage.
//
// Nothing here can kill the hero — no ring path in rings.c touches HP,
// food, or experience — so these tests need no fortify() pinning.
// C message text, verbatim, in the terse/verbose pairs C picks between.
const (
cWearingTwo = "you already have a ring on each hand"
cWearingTwoTerse = "wearing two"
cNotARing = "it would be difficult to wrap that around a finger"
cNotARingTerse = "not a ring"
cNoRings = "you aren't wearing any rings"
cNoRingsTerse = "no rings"
cInUse = "That's already in use"
cCursed = "you can't. It appears to be cursed"
)
// ringSeed is the fixed seed every test here runs on: nothing in rings.c
// depends on the layout, but the RNG stream must be reproducible for the
// ring_eat chance rolls.
const ringSeed = 5
// mkRingGame builds a headless game with a clear message line, so that a
// leftover mpos cannot turn the next msg() into a --More-- that eats the
// scripted keystrokes.
func mkRingGame(t *testing.T) *RogueGame {
t.Helper()
g := mkGame(t, ringSeed)
g.Msgs.Mpos = 0
g.Msgs.Huh = ""
return g
}
// handKeys scripts an answer to gethand and appends an abort tail. Without
// it, a port that stopped accepting the key under test would reprompt
// forever against the headless terminal's filler input, and the test would
// die of the 30s timeout instead of failing on its own assertion. The
// space acknowledges the reprompt's --More-- and the ESCAPE makes gethand
// give up, so the assertion gets to run and say what actually went wrong.
// For the same reason, a call that must not prompt at all is scripted with
// a lone ESCAPE rather than an empty script.
func handKeys(keys ...byte) []byte {
return append(keys, ' ', Escape)
}
// mkRing builds a ring of the given kind; bonus is C's o_arm.
func mkRing(kind RingKind, bonus int) *Object {
obj := newObject()
obj.Kind = KindRing
obj.Which = int(kind)
obj.Bonus = bonus
obj.Count = 1
return obj
}
// wear puts a ring straight onto a hand the way a restored save would,
// bypassing ring_on's prompting and effects.
func wear(g *RogueGame, hand int, obj *Object) *Object {
give(g, obj)
g.Player.CurRing[hand] = obj
return obj
}
func handDesc(obj *Object) string {
if obj == nil {
return "empty"
}
return fmt.Sprintf("ring kind %d", obj.RingKind())
}
// assertHands pins both hands at once, which is what "no state change"
// means for every rejection path in ring_on.
func assertHands(t *testing.T, g *RogueGame, left, right *Object) {
t.Helper()
if g.Player.CurRing[Left] != left {
t.Errorf("left hand = %s, want %s",
handDesc(g.Player.CurRing[Left]), handDesc(left))
}
if g.Player.CurRing[Right] != right {
t.Errorf("right hand = %s, want %s",
handDesc(g.Player.CurRing[Right]), handDesc(right))
}
}
// TestRingOnUsesTheHandTheHeroPicks covers the first arm of C's ring_on
// hand choice: "if (cur_ring[LEFT] == NULL && cur_ring[RIGHT] == NULL)
// { if ((ring = gethand()) < 0) return; }".
func TestRingOnUsesTheHandTheHeroPicks(t *testing.T) {
t.Parallel()
for _, tc := range []struct {
name string
key byte
hand int
}{
{"lower l", 'l', Left},
{"upper L", 'L', Left},
{"lower r", 'r', Right},
{"upper R", 'R', Right},
} {
t.Run(tc.name, func(t *testing.T) {
t.Parallel()
g := mkRingGame(t)
ring := mkRing(RingAdornment, 0)
ch := give(g, ring)
setInput(t, g, handKeys(ch, tc.key)...)
g.ringOn()
if tc.hand == Left {
assertHands(t, g, ring, nil)
} else {
assertHands(t, g, nil, ring)
}
})
}
}
// TestRingOnEscapeFromGethandWearsNothing is the "< 0" half of that arm.
func TestRingOnEscapeFromGethandWearsNothing(t *testing.T) {
t.Parallel()
g := mkRingGame(t)
ring := mkRing(RingAdornment, 0)
ch := give(g, ring)
setInput(t, g, ch, Escape)
g.ringOn()
assertHands(t, g, nil, nil)
}
// TestRingOnTakesTheOnlyFreeHandWithoutAsking covers C's second and third
// arms — "else if (cur_ring[LEFT] == NULL) ring = LEFT" and the RIGHT
// mirror — which must not prompt. The scripted hand key is deliberately
// the wrong hand: a port that asked anyway would consume it and put the
// ring on the occupied side's opposite, failing here instead of hanging.
func TestRingOnTakesTheOnlyFreeHandWithoutAsking(t *testing.T) {
t.Parallel()
for _, tc := range []struct {
name string
worn int
free int
badKey byte
}{
{"left already worn", Left, Right, 'l'},
{"right already worn", Right, Left, 'r'},
} {
t.Run(tc.name, func(t *testing.T) {
t.Parallel()
g := mkRingGame(t)
old := wear(g, tc.worn, mkRing(RingStealth, 0))
ring := mkRing(RingAdornment, 0)
ch := give(g, ring)
setInput(t, g, handKeys(ch, tc.badKey)...)
g.ringOn()
if g.Player.CurRing[tc.free] != ring {
t.Errorf("free hand = %s, want the new ring",
handDesc(g.Player.CurRing[tc.free]))
}
if g.Player.CurRing[tc.worn] != old {
t.Error("ring_on disturbed the hand that was already worn")
}
})
}
}
// TestRingOnWithBothHandsFullIsRejected covers C's final else arm. The
// trailing ESCAPE is scripted so that a port which wrongly fell through
// to gethand() aborts instead of looping on the exhausted script.
func TestRingOnWithBothHandsFullIsRejected(t *testing.T) {
t.Parallel()
for _, tc := range []struct {
name string
terse bool
want string
}{
{"wearing two, verbose", false, cWearingTwo},
{"wearing two, terse", true, cWearingTwoTerse},
} {
t.Run(tc.name, func(t *testing.T) {
t.Parallel()
g := mkRingGame(t)
g.Options.Terse = tc.terse
left := wear(g, Left, mkRing(RingStealth, 0))
right := wear(g, Right, mkRing(RingRegeneration, 0))
ch := give(g, mkRing(RingAdornment, 0))
setInput(t, g, ch, Escape)
g.ringOn()
if g.Msgs.Huh != tc.want {
t.Errorf("message = %q, want %q", g.Msgs.Huh, tc.want)
}
assertHands(t, g, left, right)
})
}
}
// TestRingOnRejectsANonRing covers C's "if (obj->o_type != RING)" guard.
func TestRingOnRejectsANonRing(t *testing.T) {
t.Parallel()
for _, tc := range []struct {
name string
terse bool
want string
}{
{"not a ring, verbose", false, cNotARing},
{"not a ring, terse", true, cNotARingTerse},
} {
t.Run(tc.name, func(t *testing.T) {
t.Parallel()
g := mkRingGame(t)
g.Options.Terse = tc.terse
pot := newObject()
pot.Kind = KindPotion
pot.Which = int(PotionHealing)
ch := give(g, pot)
setInput(t, g, ch, Escape)
g.ringOn()
if g.Msgs.Huh != tc.want {
t.Errorf("message = %q, want %q", g.Msgs.Huh, tc.want)
}
assertHands(t, g, nil, nil)
})
}
}
// TestRingOnRejectsARingAlreadyWorn covers C's "if (is_current(obj))
// return", which sits between the type check and the hand choice.
func TestRingOnRejectsARingAlreadyWorn(t *testing.T) {
t.Parallel()
g := mkRingGame(t)
worn := wear(g, Left, mkRing(RingStealth, 0))
setInput(t, g, worn.PackCh, Escape)
g.ringOn()
if g.Msgs.Huh != cInUse {
t.Errorf("message = %q, want %q", g.Msgs.Huh, cInUse)
}
assertHands(t, g, worn, nil)
}
// TestRingOnAddStrengthAndRingOffReverseEachOther pins the R_ADDSTR arm
// of ring_on ("case R_ADDSTR: chg_str(obj->o_arm)") against the R_ADDSTR
// arm of things.c dropcheck ("chg_str(-obj->o_arm)").
func TestRingOnAddStrengthAndRingOffReverseEachOther(t *testing.T) {
t.Parallel()
g := mkRingGame(t)
ring := mkRing(RingAddStrength, 2)
ch := give(g, ring)
base := g.Player.Stats.Str
setInput(t, g, handKeys(ch, 'l')...)
g.ringOn()
if g.Player.Stats.Str != base+2 {
t.Errorf("strength after wearing = %d, want %d",
g.Player.Stats.Str, base+2)
}
assertHands(t, g, ring, nil)
// Only the left hand is worn, so ring_off's "else if (cur_ring[RIGHT]
// == NULL) ring = LEFT" arm picks it with no prompt.
setInput(t, g, Escape)
g.ringOff()
if g.Player.Stats.Str != base {
t.Errorf("strength after removal = %d, want %d",
g.Player.Stats.Str, base)
}
assertHands(t, g, nil, nil)
}
// TestRingOnSeeInvisibleAndRingOffUndoIt pins the R_SEEINVIS arms:
// invis_on() on the way in, unsee() plus extinguish(unsee) on the way
// out. The pending fuse stands in for a potion of see invisible still
// running, which is the only way the extinguish is observable.
func TestRingOnSeeInvisibleAndRingOffUndoIt(t *testing.T) {
t.Parallel()
g := mkRingGame(t)
ring := mkRing(RingSeeInvisible, 0)
ch := give(g, ring)
setInput(t, g, handKeys(ch, 'r')...)
g.ringOn()
if !g.Player.On(CanSeeInvisible) {
t.Error("ring of see invisible did not set CanSeeInvisible")
}
g.Fuse(DUnsee, 0, 100, After)
setInput(t, g, Escape)
g.ringOff()
if g.Player.On(CanSeeInvisible) {
t.Error("taking the ring off left CanSeeInvisible set")
}
if g.findSlot(DUnsee) != nil {
t.Error("taking the ring off did not extinguish the unsee fuse")
}
}
// TestRingOnAggravateMonstersWakesThem pins the R_AGGR arm, which calls
// aggravate() — misc.c walks every monster through runTo, setting ISRUN.
func TestRingOnAggravateMonstersWakesThem(t *testing.T) {
t.Parallel()
g := mkRingGame(t)
tp := spawnAdjacent(g, 'Z')
tp.Flags.Clear(Awake)
ring := mkRing(RingAggravateMonsters, 0)
ch := give(g, ring)
setInput(t, g, handKeys(ch, 'l')...)
g.ringOn()
if !tp.On(Awake) {
t.Error("ring of aggravate monsters did not wake the monster")
}
}
// TestGethand covers rings.c gethand end to end. The bad-key case needs
// the extra space: the reprompt happens with mpos still set from "please
// type L or R", so endmsg puts up a --More-- that wait_for absorbs.
func TestGethand(t *testing.T) {
t.Parallel()
for _, tc := range []struct {
name string
input []byte
want int
}{
{"l", []byte{'l'}, Left},
{"L", []byte{'L'}, Left},
{"r", []byte{'r'}, Right},
{"R", []byte{'R'}, Right},
{"escape aborts", []byte{Escape}, -1},
{"bad key reprompts", []byte{'x', ' ', 'r'}, Right},
} {
t.Run(tc.name, func(t *testing.T) {
t.Parallel()
g := mkRingGame(t)
setInput(t, g, handKeys(tc.input...)...)
if got := g.gethand(); got != tc.want {
t.Errorf("gethand() = %d, want %d", got, tc.want)
}
})
}
}
// TestRingOffWithNoRingsSaysSo covers ring_off's first arm.
func TestRingOffWithNoRingsSaysSo(t *testing.T) {
t.Parallel()
for _, tc := range []struct {
name string
terse bool
want string
}{
{"no rings, verbose", false, cNoRings},
{"no rings, terse", true, cNoRingsTerse},
} {
t.Run(tc.name, func(t *testing.T) {
t.Parallel()
g := mkRingGame(t)
g.Options.Terse = tc.terse
setInput(t, g, Escape)
g.ringOff()
if g.Msgs.Huh != tc.want {
t.Errorf("message = %q, want %q", g.Msgs.Huh, tc.want)
}
})
}
}
// TestRingOffWithBothHandsWornAsksWhich covers ring_off's else arm, both
// the answer and the "(ring = gethand()) < 0" abort.
func TestRingOffWithBothHandsWornAsksWhich(t *testing.T) {
t.Parallel()
for _, tc := range []struct {
name string
key byte
gone int
stays int
}{
{"takes off the left", 'l', Left, Right},
{"takes off the right", 'r', Right, Left},
} {
t.Run(tc.name, func(t *testing.T) {
t.Parallel()
g := mkRingGame(t)
rings := [2]*Object{
Left: wear(g, Left, mkRing(RingStealth, 0)),
Right: wear(g, Right, mkRing(RingRegeneration, 0)),
}
setInput(t, g, handKeys(tc.key)...)
g.ringOff()
if g.Player.CurRing[tc.gone] != nil {
t.Errorf("chosen hand still holds %s",
handDesc(g.Player.CurRing[tc.gone]))
}
if g.Player.CurRing[tc.stays] != rings[tc.stays] {
t.Error("ring_off cleared the hand that was not chosen")
}
})
}
}
// TestRingOffEscapeKeepsBothRings is the abort half of that arm.
func TestRingOffEscapeKeepsBothRings(t *testing.T) {
t.Parallel()
g := mkRingGame(t)
left := wear(g, Left, mkRing(RingStealth, 0))
right := wear(g, Right, mkRing(RingRegeneration, 0))
setInput(t, g, Escape)
g.ringOff()
assertHands(t, g, left, right)
}
// TestRingOffCursedRingStaysOn covers the dropcheck gate ring_off runs
// its removal through: things.c returns FALSE for an ISCURSED item after
// printing this message, and the hand is left alone.
func TestRingOffCursedRingStaysOn(t *testing.T) {
t.Parallel()
g := mkRingGame(t)
ring := mkRing(RingAddStrength, -1)
ring.Flags.Set(Cursed)
wear(g, Left, ring)
setInput(t, g, Escape)
g.ringOff()
if g.Msgs.Huh != cCursed {
t.Errorf("message = %q, want %q", g.Msgs.Huh, cCursed)
}
assertHands(t, g, ring, nil)
}
// cRingUse is one entry of the rings.c ring_eat uses[] table.
type cRingUse struct {
kind RingKind
name string // the C R_ name, for failure messages
uses int
}
// cRingUses transcribes ring_eat's static uses[] verbatim:
//
// static int uses[] = {
// 1, /* R_PROTECT */ 1, /* R_ADDSTR */
// 1, /* R_SUSTSTR */ -3, /* R_SEARCH */
// -5, /* R_SEEINVIS */ 0, /* R_NOP */
// 0, /* R_AGGR */ -3, /* R_ADDHIT */
// -3, /* R_ADDDAM */ 2, /* R_REGEN */
// -2, /* R_DIGEST */ 0, /* R_TELEPORT */
// 1, /* R_STEALTH */ 1 /* R_SUSTARM */
// };
//
// A negative entry is not a cost: C computes eat = (rnd(-eat) == 0), a
// one-in-n chance of a single unit. R_DIGEST then flips the sign, so slow
// digestion returns 0 or -1 and is the only ring that gives food back.
func cRingUses() []cRingUse {
return []cRingUse{
{RingProtection, "R_PROTECT", 1},
{RingAddStrength, "R_ADDSTR", 1},
{RingSustainStrength, "R_SUSTSTR", 1},
{RingSearching, "R_SEARCH", -3},
{RingSeeInvisible, "R_SEEINVIS", -5},
{RingAdornment, "R_NOP", 0},
{RingAggravateMonsters, "R_AGGR", 0},
{RingDexterity, "R_ADDHIT", -3},
{RingIncreaseDamage, "R_ADDDAM", -3},
{RingRegeneration, "R_REGEN", 2},
{RingSlowDigestion, "R_DIGEST", -2},
{RingTeleportation, "R_TELEPORT", 0},
{RingStealth, "R_STEALTH", 1},
{RingMaintainArmor, "R_SUSTARM", 1},
}
}
// TestRingEatMatchesTheCUsesTable exercises all fourteen ring kinds, both
// hands, against the C table above. This is the highest-value assertion in
// the file: ring_eat feeds the hunger clock through daemons.c, so a wrong
// entry is a silent, slow divergence from C that no other test would see.
func TestRingEatMatchesTheCUsesTable(t *testing.T) {
t.Parallel()
for _, tc := range cRingUses() {
t.Run(tc.name, func(t *testing.T) {
t.Parallel()
for _, hand := range []int{Left, Right} {
g := mkRingGame(t)
g.Player.CurRing[hand] = mkRing(tc.kind, 0)
if tc.uses >= 0 {
assertFixedRingEat(t, g, hand, tc)
} else {
assertChanceRingEat(t, g, hand, tc)
}
}
})
}
}
// assertFixedRingEat checks a non-negative uses[] entry. C returns it
// unchanged and, just as importantly, never reaches rnd() on that path —
// so the generator must be untouched, or the whole game's RNG stream
// desynchronises from C's and seed compatibility is gone.
func assertFixedRingEat(t *testing.T, g *RogueGame, hand int, tc cRingUse) {
t.Helper()
for range 4 {
before := *g.Rng
if got := g.ringEat(hand); got != tc.uses {
t.Fatalf("ringEat(%d) for %s = %d, want C uses[] entry %d",
hand, tc.name, got, tc.uses)
}
if *g.Rng != before {
t.Fatalf("ringEat for %s called rnd(); C only does that for a "+
"negative uses[] entry", tc.name)
}
}
}
// assertChanceRingEat checks a negative uses[] entry. Each call is replayed
// against C's own expression from the identical generator state, which pins
// the one-in-n denominator, the sign flip R_DIGEST gets, and the fact that
// exactly one rnd() call is spent. The frequency check on top of that
// fails loudly on a wrong denominator even if the replay were ever
// weakened to agree with the code by construction.
func assertChanceRingEat(t *testing.T, g *RogueGame, hand int, tc cRingUse) {
t.Helper()
const trials = 4000
sign := 1
if tc.kind == RingSlowDigestion {
sign = -1 // rings.c: if (ring->o_which == R_DIGEST) eat = -eat
}
nonzero := 0
for range trials {
before := *g.Rng
got := g.ringEat(hand)
after := *g.Rng
// C: eat = (rnd(-eat) == 0), replayed from the same state.
*g.Rng = before
want := 0
if g.Rng.Rnd(-tc.uses) == 0 {
want = 1
}
want *= sign
if *g.Rng != after {
t.Fatalf("ringEat for %s did not spend exactly one rnd(%d) call",
tc.name, -tc.uses)
}
if got != want {
t.Fatalf("ringEat for %s = %d, want %d", tc.name, got, want)
}
if want != 0 {
nonzero++
}
}
assertOneInN(t, tc, nonzero, trials)
}
// assertOneInN checks the observed rate against C's 1/n. The tolerance is
// far tighter than the gap between the three denominators C uses (1/2,
// 1/3, 1/5) and far wider than the sampling noise at this trial count.
func assertOneInN(t *testing.T, tc cRingUse, nonzero, trials int) {
t.Helper()
const tolerance = 0.03
rate := float64(nonzero) / float64(trials)
want := 1 / float64(-tc.uses)
if math.Abs(rate-want) > tolerance {
t.Errorf("%s fired %.3f of the time over %d trials, want ~%.3f "+
"(C's one-in-%d)", tc.name, rate, trials, want, -tc.uses)
}
}
// TestRingEatEmptyHandIsZero is C's "if ((ring = cur_ring[hand]) == NULL)
// return 0" — the common case, since the hero usually wears nothing.
func TestRingEatEmptyHandIsZero(t *testing.T) {
t.Parallel()
g := mkRingGame(t)
before := *g.Rng
for _, hand := range []int{Left, Right} {
if got := g.ringEat(hand); got != 0 {
t.Errorf("ringEat(%d) with an empty hand = %d, want 0", hand, got)
}
}
if *g.Rng != before {
t.Error("ringEat on an empty hand consumed RNG")
}
}
// TestRingNum covers rings.c ring_num. Its switch ends in the `otherwise`
// macro, which rogue.h 53 defines as `break;default` — so the four labels
// R_PROTECT, R_ADDSTR, R_ADDDAM and R_ADDHIT fall through to a single
// sprintf(" [%s]", num(o_arm, 0, RING)) and every other kind returns ""
// from the default arm before the buffer is ever reached. Unknown rings
// return "" earlier still, from the ISKNOW guard.
//
// The game pointer is C's implicit global state; ring_num reads none of
// it, and the port's signature only carries one to satisfy nameit's
// prfunc type, so nil is the honest argument here.
func TestRingNum(t *testing.T) {
t.Parallel()
for _, tc := range []struct {
name string
kind RingKind
bonus int
known bool
want string
}{
{"R_PROTECT known", RingProtection, 2, true, " [+2]"},
{"R_ADDSTR known", RingAddStrength, 1, true, " [+1]"},
{"R_ADDDAM known", RingIncreaseDamage, -1, true, " [-1]"},
{"R_ADDHIT known", RingDexterity, 3, true, " [+3]"},
{"R_PROTECT cursed", RingProtection, -1, true, " [-1]"},
{"R_ADDSTR unknown", RingAddStrength, 2, false, ""},
{"R_SEARCH known", RingSearching, 2, true, ""},
{"R_DIGEST known", RingSlowDigestion, 2, true, ""},
{"R_NOP known", RingAdornment, 0, true, ""},
{"R_SUSTARM known", RingMaintainArmor, 2, true, ""},
} {
t.Run(tc.name, func(t *testing.T) {
t.Parallel()
obj := mkRing(tc.kind, tc.bonus)
if tc.known {
obj.Flags.Set(Known)
}
if got := ringNum(nil, obj); got != tc.want {
t.Errorf("ringNum() = %q, want %q", got, tc.want)
}
})
}
}
// Coverage of the fourteen ring kinds, for the record:
//
// All fourteen are exercised by TestRingEatMatchesTheCUsesTable and ten of
// them by TestRingNum. Beyond that, only three kinds have a ring_on effect
// at all — R_ADDSTR, R_SEEINVIS and R_AGGR — and each has its own test
// above, paired with the dropcheck arm that undoes it. The remaining
// eleven are deliberately not given a wear/remove test: in C they are
// inert at wear time, their powers being read from ISWEARING() elsewhere
// (R_SEARCH and R_TELEPORT in the command.c per-turn tail, R_PROTECT and
// R_ADDHIT/R_ADDDAM in fight.c, R_REGEN and R_DIGEST in daemons.c,
// R_SUSTSTR and R_SUSTARM in the drain paths, R_STEALTH in chase.c), so a
// wear/remove assertion for them would test nothing that rings.c does.
// Those call sites belong to their own files' tests, not to this one.
//
// One branch is intentionally unreachable rather than untested: ring_off's
// "obj == NULL -> not wearing such a ring" cannot fire, because every arm
// that reaches it has already established that the chosen hand is worn.
// The port keeps C's defensive check; there is no state from which to
// provoke it.