update

internal/fetch/fetch_test.go

@@ -0,0 +1,128 @@
+package fetch
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+)
+
+func TestGetSuccess(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte("ok"))
+	}))
+	defer srv.Close()
+
+	c := New(Options{MaxConcurrency: 1, Retries: 0})
+	defer c.Close()
+
+	body, code, err := c.Get(context.Background(), srv.URL)
+	if err != nil || code != http.StatusOK || string(body) != "ok" {
+		t.Fatalf("期望 200/ok，得到 code=%d body=%q err=%v", code, body, err)
+	}
+}
+
+// TestGetRetriesOn5xx 5xx 应重试到上限后失败（首次 + 2 次重试 = 3 次请求）。
+func TestGetRetriesOn5xx(t *testing.T) {
+	var calls int32
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		atomic.AddInt32(&calls, 1)
+		w.WriteHeader(http.StatusInternalServerError)
+	}))
+	defer srv.Close()
+
+	c := New(Options{MaxConcurrency: 1, Retries: 2, Backoff: time.Millisecond})
+	defer c.Close()
+
+	_, code, err := c.Get(context.Background(), srv.URL)
+	if err == nil {
+		t.Fatal("500 最终应返回 error")
+	}
+	if code != http.StatusInternalServerError {
+		t.Fatalf("最终状态码应为 500，得到 %d", code)
+	}
+	if got := atomic.LoadInt32(&calls); got != 3 {
+		t.Fatalf("500 应请求 3 次（首次+2 重试），实际 %d", got)
+	}
+}
+
+// TestGetNoRetryOn4xx 4xx（非 429）不应重试。
+func TestGetNoRetryOn4xx(t *testing.T) {
+	var calls int32
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		atomic.AddInt32(&calls, 1)
+		w.WriteHeader(http.StatusNotFound)
+	}))
+	defer srv.Close()
+
+	c := New(Options{MaxConcurrency: 1, Retries: 3, Backoff: time.Millisecond})
+	defer c.Close()
+
+	_, code, err := c.Get(context.Background(), srv.URL)
+	if err == nil || code != http.StatusNotFound {
+		t.Fatalf("404 应报错且状态码 404，得到 code=%d err=%v", code, err)
+	}
+	if got := atomic.LoadInt32(&calls); got != 1 {
+		t.Fatalf("404 不应重试（只请求 1 次），实际 %d", got)
+	}
+}
+
+// TestGetRetriesOn429 429（限流）应重试，后续成功则返回成功。
+func TestGetRetriesOn429(t *testing.T) {
+	var calls int32
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if atomic.AddInt32(&calls, 1) == 1 {
+			w.WriteHeader(http.StatusTooManyRequests)
+			return
+		}
+		_, _ = w.Write([]byte("ok"))
+	}))
+	defer srv.Close()
+
+	c := New(Options{MaxConcurrency: 1, Retries: 2, Backoff: time.Millisecond})
+	defer c.Close()
+
+	body, code, err := c.Get(context.Background(), srv.URL)
+	if err != nil || code != http.StatusOK || string(body) != "ok" {
+		t.Fatalf("429 后重试应成功，得到 code=%d body=%q err=%v", code, body, err)
+	}
+}
+
+// TestConcurrencyLimit 并发上限不得被突破（修复 MaxCo² 回归的守门测试）。
+func TestConcurrencyLimit(t *testing.T) {
+	var inflight, peak int32
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		n := atomic.AddInt32(&inflight, 1)
+		for {
+			old := atomic.LoadInt32(&peak)
+			if n <= old || atomic.CompareAndSwapInt32(&peak, old, n) {
+				break
+			}
+		}
+		time.Sleep(20 * time.Millisecond)
+		atomic.AddInt32(&inflight, -1)
+		_, _ = w.Write([]byte("ok"))
+	}))
+	defer srv.Close()
+
+	const limit = 2
+	c := New(Options{MaxConcurrency: limit, Retries: 0})
+	defer c.Close()
+
+	var wg sync.WaitGroup
+	for i := 0; i < 8; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			_, _, _ = c.Get(context.Background(), srv.URL)
+		}()
+	}
+	wg.Wait()
+
+	if m := atomic.LoadInt32(&peak); m > limit {
+		t.Fatalf("并发峰值不应超过 %d，实际 %d", limit, m)
+	}
+}