feat: add jikan client observability, dedup, and stale-while-revalidate

integrations/jikan/client_test.go

@@ -0,0 +1,93 @@
+package jikan
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"io"
+	"mal/internal/db"
+	"net/http"
+	"strings"
+	"testing"
+	"time"
+
+	_ "github.com/mattn/go-sqlite3"
+)
+
+type roundTripFunc func(*http.Request) (*http.Response, error)
+
+func (fn roundTripFunc) RoundTrip(req *http.Request) (*http.Response, error) {
+	return fn(req)
+}
+
+func TestGetWithCacheReturnsStaleAndRefreshesAsync(t *testing.T) {
+	sqlDB, err := sql.Open("sqlite3", ":memory:")
+	if err != nil {
+		t.Fatalf("open sqlite: %v", err)
+	}
+	defer sqlDB.Close()
+	sqlDB.SetMaxOpenConns(1)
+
+	_, err = sqlDB.Exec(`
+		CREATE TABLE jikan_cache (
+			key TEXT PRIMARY KEY,
+			data TEXT NOT NULL,
+			expires_at DATETIME NOT NULL,
+			created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
+		);
+	`)
+	if err != nil {
+		t.Fatalf("create cache table: %v", err)
+	}
+
+	queries := db.New(sqlDB)
+	client := NewClient(queries)
+	stale := TopAnimeResponse{Data: []Anime{{MalID: 1, Title: "stale"}}}
+	staleBytes, err := json.Marshal(stale)
+	if err != nil {
+		t.Fatalf("marshal stale response: %v", err)
+	}
+
+	_, err = sqlDB.Exec(
+		`INSERT INTO jikan_cache (key, data, expires_at) VALUES (?, ?, ?)`,
+		"top:1",
+		string(staleBytes),
+		time.Now().Add(-time.Hour),
+	)
+	if err != nil {
+		t.Fatalf("insert stale cache: %v", err)
+	}
+
+	client.httpClient = &http.Client{
+		Transport: roundTripFunc(func(*http.Request) (*http.Response, error) {
+			body := `{"data":[{"mal_id":2,"title":"fresh"}]}`
+			return &http.Response{
+				StatusCode: http.StatusOK,
+				Body:       io.NopCloser(strings.NewReader(body)),
+				Header:     make(http.Header),
+			}, nil
+		}),
+	}
+
+	var got TopAnimeResponse
+	if err := client.getWithCache(context.Background(), "top:1", time.Hour, "https://example.test/top", &got); err != nil {
+		t.Fatalf("getWithCache: %v", err)
+	}
+	if len(got.Data) != 1 || got.Data[0].Title != "stale" {
+		t.Fatalf("got %+v, want stale cache response", got.Data)
+	}
+
+	deadline := time.Now().Add(2 * time.Second)
+	for time.Now().Before(deadline) {
+		var refreshed TopAnimeResponse
+		if client.getCache(context.Background(), "top:1", &refreshed) && len(refreshed.Data) == 1 && refreshed.Data[0].Title == "fresh" {
+			return
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+
+	var rawData string
+	var rawExpires string
+	_ = sqlDB.QueryRow(`SELECT data, expires_at FROM jikan_cache WHERE key = ?`, "top:1").Scan(&rawData, &rawExpires)
+	t.Fatalf("cache was not refreshed asynchronously; data=%s expires_at=%s", rawData, rawExpires)
+}