1 files changed, 77 insertions, 0 deletions
diff --git a/internal/bufpool/buffers_test.go b/internal/bufpool/buffers_test.go
new file mode 100644
index 00000000..f5c006da
--- /dev/null
+++ b/internal/bufpool/buffers_test.go
@@ -0,0 +1,77 @@
+package bufpool
+
+import "testing"
+
+func TestBorrowBufferResizeAndAppend(t *testing.T) {
+	b := Borrow(1)
+	defer b.Release()
+
+	if cap(b.buf) < DefaultBufferCap {
+		t.Fatalf("expected capacity >= %d, got %d", DefaultBufferCap, cap(b.buf))
+	}
+
+	b.Append([]byte("alpha"))
+	b.Append([]byte("beta"))
+	if got := string(b.Bytes()); got != "alphabeta" {
+		t.Fatalf("unexpected contents: %q", got)
+	}
+
+	b.Resize(3)
+	if got := string(b.Bytes()); got != "alp" {
+		t.Fatalf("resize shrink mismatch: %q", got)
+	}
+
+	b.Resize(8)
+	if len(b.Bytes()) != 8 {
+		t.Fatalf("expected len 8 after grow, got %d", len(b.Bytes()))
+	}
+	if prefix := string(b.Bytes()[:3]); prefix != "alp" {
+		t.Fatalf("prefix lost after grow: %q", prefix)
+	}
+}
+
+func TestBorrowBufferRelease(t *testing.T) {
+	b := Borrow(DefaultBufferCap / 2)
+	b.Append([]byte("data"))
+	b.Release()
+	if b.buf != nil {
+		t.Fatal("expected buffer cleared after release")
+	}
+}
+
+func TestBorrowUsesLargerPools(t *testing.T) {
+	const request = DefaultBufferCap * 4
+
+	classIdx, classCap, pooled := classFor(request)
+	if !pooled {
+		t.Fatalf("expected %d to map to a pooled class", request)
+	}
+
+	b := Borrow(request)
+	if b.pool != poolIndex(classIdx) {
+		t.Fatalf("expected pooled buffer in class %d, got %d", classIdx, b.pool)
+	}
+	if cap(b.buf) != classCap {
+		t.Fatalf("expected capacity %d, got %d", classCap, cap(b.buf))
+	}
+	b.Release()
+
+	b2 := Borrow(request)
+	defer b2.Release()
+	if b2.pool != poolIndex(classIdx) {
+		t.Fatalf("expected pooled buffer in class %d on reuse, got %d", classIdx, b2.pool)
+	}
+	if cap(b2.buf) != classCap {
+		t.Fatalf("expected capacity %d on reuse, got %d", classCap, cap(b2.buf))
+	}
+}
+
+func TestGrowingBufferStaysPooled(t *testing.T) {
+	b := Borrow(DefaultBufferCap)
+	defer b.Release()
+
+	b.Append(make([]byte, DefaultBufferCap*3))
+	if b.pool == unpooled {
+		t.Fatal("buffer should stay pooled after growth within limit")
+	}
+}