feat: add canonical matchmaking rating engine

2026-09-15 06:02:13 +00:00 · 2026-08-31 20:25:07 +01:00
parent 7643dbc439
commit 1793eb7621
3 changed files with 185 additions and 1 deletions
@@ -0,0 +1,49 @@
+package domain
+
+import (
+	"math"
+	"testing"
+	"time"
+)
+
+func TestUpdateRatingMatchesCanonicalGlicko2Example(t *testing.T) {
+	current := Rating{Value: 1500, RD: 200, Volatility: 0.06}
+	opponents := []Opponent{
+		{PlayerID: "a", Rating: Rating{Value: 1400, RD: 30, Volatility: 0.06}, Score: 1, Weight: 1},
+		{PlayerID: "b", Rating: Rating{Value: 1550, RD: 100, Volatility: 0.06}, Score: 0, Weight: 1},
+		{PlayerID: "c", Rating: Rating{Value: 1700, RD: 300, Volatility: 0.06}, Score: 0, Weight: 1},
+	}
+	updated, err := UpdateRating(current, opponents, time.Unix(100000, 0))
+	if err != nil { t.Fatal(err) }
+	if math.Abs(updated.Value-1464.06) > 0.1 || math.Abs(updated.RD-151.52) > 0.1 || math.Abs(updated.Volatility-0.05999) > 0.0001 {
+		t.Fatalf("canonical vector mismatch: %+v", updated)
+	}
+}
+
+func TestRatingInactivityRaisesRDWithoutChangingRating(t *testing.T) {
+	now := time.Unix(100000, 0)
+	current := Rating{Value: 1600, RD: 100, Volatility: 0.06, LastRatedAt: now}
+	updated, err := UpdateRating(current, nil, now.Add(48*time.Hour+time.Hour))
+	if err != nil { t.Fatal(err) }
+	if updated.Value != current.Value || updated.RD <= current.RD || updated.RD > GlickoInitialRD { t.Fatalf("bad inactivity update: %+v", updated) }
+}
+
+func TestOpponentWeightHelpersAreExactAndDeterministic(t *testing.T) {
+	opponents := []Opponent{{PlayerID: "c", Rating: Rating{Value: 1700}}, {PlayerID: "a", Rating: Rating{Value: 1400}}, {PlayerID: "b", Rating: Rating{Value: 1550}}}
+	ranked, err := RankedOpponents(opponents)
+	if err != nil { t.Fatal(err) }
+	if ranked[0].PlayerID != "a" || ranked[0].Weight != 1.0/3.0 { t.Fatalf("ranked weighting/order wrong: %+v", ranked) }
+	reordered, err := RankedOpponents([]Opponent{opponents[1], opponents[0], opponents[2]})
+	if err != nil { t.Fatal(err) }
+	for i := range ranked { if ranked[i].PlayerID != reordered[i].PlayerID { t.Fatal("input order changed opponent order") } }
+	casual, err := CasualOpponents(opponents[:2])
+	if err != nil { t.Fatal(err) }
+	if casual[0].Weight != 0.5 || casual[1].Weight != 0.5 { t.Fatalf("casual weighting wrong: %+v", casual) }
+}
+
+func TestRatingRejectsInvalidStateAndBadScore(t *testing.T) {
+	_, err := UpdateRating(Rating{Value: 1500, RD: 0, Volatility: 0.06}, nil, time.Now())
+	if err == nil { t.Fatal("accepted zero RD") }
+	_, err = UpdateRating(Rating{Value: 1500, RD: 200, Volatility: 0.06}, []Opponent{{Rating: Rating{Value: 1500, RD: 100, Volatility: 0.06}, Weight: 1, Score: 2}}, time.Now())
+	if err == nil { t.Fatal("accepted score outside [0,1]") }
+}