bvandeusenandClaude Opus 5.5
fcf5b7e5a8
The same rewrite as d191a282, for four packages whose comments carried the
most history: tuning stories, quotes from the operator, single-install
measurements in library_scale.go, and 'used to' accounts of bugs. The
constraint each story protected stays as a present-tense reason (why tier 3
is reduced not removed, why the randomised arms take an order seed, why the
seed artist is eligible in Songs-like). Comments naming system_cron.go and
config.RecommendationConfig, neither of which holds what they claimed, now
name the scheduler and internal/recsettings.
Checked: non-comment tokens identical to HEAD; gofmt clean.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
105 lines
3.3 KiB
Go
105 lines
3.3 KiB
Go
package playlists
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import (
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"testing"
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"github.com/jackc/pgx/v5/pgtype"
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)
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func mixTrack(b byte, kind string) discoverTrack {
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return discoverTrack{ID: pgtype.UUID{Bytes: [16]byte{b}, Valid: true}, PickKind: kind}
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}
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func idsOf(pool []discoverTrack) []byte {
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out := make([]byte, len(pool))
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for i, t := range pool {
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out[i] = t.ID.Bytes[0]
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}
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return out
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}
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func TestRotateForDay_RotatesWithinTierBlocks(t *testing.T) {
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// Tiered pools arrive tier-ordered; rotation must vary the daily
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// slice WITHIN each tier without hoisting tier-3 filler above
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// tier-1's exact fits.
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pool := []discoverTrack{
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mixTrack(1, pickKindTier1), mixTrack(2, pickKindTier1), mixTrack(3, pickKindTier1),
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mixTrack(4, pickKindTier2), mixTrack(5, pickKindTier2),
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mixTrack(6, pickKindTier3),
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}
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u := pgtype.UUID{Bytes: [16]byte{42}, Valid: true}
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got := rotateForDay(pool, u, "2026-07-03")
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if len(got) != len(pool) {
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t.Fatalf("len = %d, want %d", len(got), len(pool))
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}
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wantKinds := []string{
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pickKindTier1, pickKindTier1, pickKindTier1,
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pickKindTier2, pickKindTier2, pickKindTier3,
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}
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for i, k := range wantKinds {
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if got[i].PickKind != k {
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t.Fatalf("pos %d kind = %q, want %q (tier order broken: %v)",
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i, got[i].PickKind, k, idsOf(got))
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}
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}
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// Each block is a rotation of its input: contiguity check for the
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// 3-element tier-1 block (successor relation preserved cyclically).
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wantOrder := map[byte]byte{1: 2, 2: 3, 3: 1}
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for i := 0; i < 2; i++ {
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if got[i+1].ID.Bytes[0] != wantOrder[got[i].ID.Bytes[0]] {
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t.Errorf("tier1 block is not a rotation: %v", idsOf(got[:3]))
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break
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}
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}
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// Determinism within a day.
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again := rotateForDay(pool, u, "2026-07-03")
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for i := range got {
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if got[i].ID != again[i].ID {
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t.Fatal("rotation must be deterministic for the same (user, day)")
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}
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}
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}
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func TestRotateForDay_UntieredPoolIsWholeRotation(t *testing.T) {
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// Untiered pools (all PickKind "") are one block — the original
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// whole-pool rotation semantics.
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pool := []discoverTrack{mixTrack(1, ""), mixTrack(2, ""), mixTrack(3, ""), mixTrack(4, "")}
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got := rotateForDay(pool, pgtype.UUID{Bytes: [16]byte{7}, Valid: true}, "2026-07-03")
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if len(got) != 4 {
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t.Fatalf("len = %d, want 4", len(got))
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}
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wantNext := map[byte]byte{1: 2, 2: 3, 3: 4, 4: 1}
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for i := 0; i < 3; i++ {
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cur, next := got[i].ID.Bytes[0], got[i+1].ID.Bytes[0]
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if wantNext[cur] != next {
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t.Errorf("not a rotation of the input: %v", idsOf(got))
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break
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}
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}
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}
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func TestFinishMix_PropagatesPickKind(t *testing.T) {
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// Tier stamps ride discoverTrack through diversify/truncate into
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// the rankedCandidates that insertSystemPlaylist persists.
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pool := []discoverTrack{mixTrack(1, pickKindTier1), mixTrack(2, pickKindTier2)}
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got := finishMix(pool, false)
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if len(got) != 2 {
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t.Fatalf("len = %d, want 2", len(got))
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}
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if got[0].PickKind != pickKindTier1 || got[1].PickKind != pickKindTier2 {
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t.Errorf("pick kinds = %q, %q — want tier1, tier2", got[0].PickKind, got[1].PickKind)
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}
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}
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func TestPickKindForMixTier(t *testing.T) {
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cases := []struct {
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tier int32
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want string
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}{{1, pickKindTier1}, {2, pickKindTier2}, {3, pickKindTier3}, {9, pickKindTier3}}
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for _, c := range cases {
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if got := pickKindForMixTier(c.tier); got != c.want {
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t.Errorf("pickKindForMixTier(%d) = %q, want %q", c.tier, got, c.want)
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}
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}
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}
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