137 lines
4.0 KiB
Go
137 lines
4.0 KiB
Go
package recommend
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import (
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"encoding/json"
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"strings"
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"testing"
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)
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func explainItem(t *testing.T, payload string) Item {
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t.Helper()
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items := Decode([]json.RawMessage{json.RawMessage(payload)})
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if len(items) != 1 {
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t.Fatalf("payload did not decode to one item: %s", payload)
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}
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return items[0]
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}
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func explainProfile(t *testing.T, history ...string) Profile {
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t.Helper()
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items := make([]Item, 0, len(history))
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for _, payload := range history {
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items = append(items, explainItem(t, payload))
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}
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return BuildProfile(items, nil)
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}
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const thrillerHistory = `{
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"Id":"h1","Name":"Sicario","Type":"Movie","Genres":["Thriller","Crime"],
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"Studios":[{"Name":"Lionsgate"}],
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"People":[{"Name":"Denis Villeneuve","Type":"Director"},{"Name":"Emily Blunt","Type":"Actor"}]
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}`
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func TestWhyNamesTheGenreTheViewerActuallyWatches(t *testing.T) {
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profile := explainProfile(t, thrillerHistory)
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candidate := explainItem(t, `{
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"Id":"c1","Name":"Prisoners","Type":"Movie","Genres":["Thriller"],
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"People":[{"Name":"Denis Villeneuve","Type":"Director"}]
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}`)
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reasons := Why(profile, candidate, ReasonLimit)
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if len(reasons) == 0 || reasons[0] != "Because you watch Thriller" {
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t.Fatalf("expected the genre reason first, got %v", reasons)
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}
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if !strings.Contains(strings.Join(reasons, "|"), "Denis Villeneuve") {
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t.Fatalf("expected the shared director to be named, got %v", reasons)
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}
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}
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func TestWhyNeverClaimsAnAffinityThatIsNotThere(t *testing.T) {
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profile := explainProfile(t, thrillerHistory)
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candidate := explainItem(t, `{
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"Id":"c2","Name":"Paddington","Type":"Movie","Genres":["Family"],
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"CommunityRating":8.2,
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"People":[{"Name":"Paul King","Type":"Director"}]
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}`)
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reasons := Why(profile, candidate, ReasonLimit)
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for _, reason := range reasons {
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if strings.HasPrefix(reason, "Because you watch") ||
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strings.HasPrefix(reason, "You've watched") {
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t.Fatalf("invented a taste the profile does not hold: %v", reasons)
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}
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}
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if len(reasons) == 0 || reasons[0] != "Well rated (8.2)" {
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t.Fatalf("expected the catalogue fact to carry the strip, got %v", reasons)
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}
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}
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func TestWhyAlwaysSaysSomething(t *testing.T) {
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candidate := explainItem(t, `{"Id":"c3","Name":"Unknown","Type":"Movie","Genres":["Drama"]}`)
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reasons := Why(Profile{}, candidate, ReasonLimit)
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if len(reasons) != 1 || reasons[0] != "Drama from your library" {
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t.Fatalf("an empty profile should still explain the title, got %v", reasons)
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}
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}
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func TestWhyIsCappedAndOrdered(t *testing.T) {
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// A second, Thriller-only title so Thriller genuinely outweighs Crime — with one
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// history item they tie and the alphabetical tie-break would decide it.
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profile := explainProfile(t, thrillerHistory, `{
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"Id":"h2","Name":"Nightcrawler","Type":"Movie","Genres":["Thriller"],
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"Studios":[{"Name":"Lionsgate"}],
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"People":[{"Name":"Emily Blunt","Type":"Actor"}]
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}`)
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candidate := explainItem(t, `{
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"Id":"c4","Name":"Wind River","Type":"Movie","Genres":["Thriller","Crime"],
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"Studios":[{"Name":"Lionsgate"}],"CommunityRating":9.1,"ProductionYear":2017,
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"People":[{"Name":"Emily Blunt","Type":"Actor"}]
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}`)
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reasons := Why(profile, candidate, ReasonLimit)
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if len(reasons) != ReasonLimit {
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t.Fatalf("expected exactly %d reasons, got %v", ReasonLimit, reasons)
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}
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want := []string{
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"Because you watch Thriller",
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"You've watched Emily Blunt before",
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"More from Lionsgate",
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}
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for i, reason := range want {
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if reasons[i] != reason {
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t.Fatalf("reason %d: want %q, got %q (%v)", i, reason, reasons[i], reasons)
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}
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}
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}
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func TestWhyIsStableAcrossCalls(t *testing.T) {
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profile := explainProfile(t, thrillerHistory)
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candidate := explainItem(t, `{
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"Id":"c5","Name":"Hell or High Water","Type":"Movie","Genres":["Crime","Thriller"]
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}`)
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first := Why(profile, candidate, ReasonLimit)
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for i := 0; i < 20; i++ {
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if got := Why(profile, candidate, ReasonLimit); !equalStrings(first, got) {
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t.Fatalf("reasons changed between calls: %v then %v", first, got)
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}
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}
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}
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func equalStrings(a, b []string) bool {
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if len(a) != len(b) {
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return false
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}
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for i := range a {
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if a[i] != b[i] {
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return false
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}
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}
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return true
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}
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