tests(eviction): add zero-capacity and delete-path tests for LRU, LFU, Clock, CAWOLFU; fix Evict key handling in Clock & CAWOLFU

Author: hyp3rd

pkg/eviction/cawolfu_test.go

@@ -46,3 +46,39 @@ func TestCAWOLFU_EvictMethodOrder(t *testing.T) {
 		t.Fatalf("expected to evict 'b' second, got %q ok=%v", key, ok)
 	}
 }
+
+func TestCAWOLFU_ZeroCapacity_NoOp(t *testing.T) {
+	c, err := NewCAWOLFU(0)
+	if err != nil {
+		t.Fatalf("NewCAWOLFU error: %v", err)
+	}
+
+	c.Set("a", 1)
+	if _, ok := c.Get("a"); ok {
+		t.Fatalf("expected Get to miss on zero-capacity cache")
+	}
+
+	if key, ok := c.Evict(); ok || key != "" {
+		t.Fatalf("expected no eviction on zero-capacity, got %q ok=%v", key, ok)
+	}
+}
+
+func TestCAWOLFU_Delete_RemovesItem(t *testing.T) {
+	c, err := NewCAWOLFU(2)
+	if err != nil {
+		t.Fatalf("NewCAWOLFU error: %v", err)
+	}
+
+	c.Set("a", 1)
+	c.Set("b", 2)
+	c.Delete("a")
+
+	if _, ok := c.Get("a"); ok {
+		t.Fatalf("expected 'a' to be deleted")
+	}
+
+	key, ok := c.Evict()
+	if !ok || key != "b" {
+		t.Fatalf("expected to evict 'b' as remaining item, got %q ok=%v", key, ok)
+	}
+}

pkg/eviction/clock_test.go

@@ -41,3 +41,48 @@ func TestClock_EvictsWhenHandFindsColdPage(t *testing.T) {
 		t.Fatalf("expected to evict 'a' second, got %q ok=%v", key, ok)
 	}
 }
+
+func TestClock_ZeroCapacity_NoOp(t *testing.T) {
+	clk, err := NewClockAlgorithm(0)
+	if err != nil {
+		t.Fatalf("NewClockAlgorithm error: %v", err)
+	}
+
+	clk.Set("a", 1)
+	if _, ok := clk.Get("a"); ok {
+		t.Fatalf("expected Get to miss on zero-capacity cache")
+	}
+
+	if key, ok := clk.Evict(); ok || key != "" {
+		t.Fatalf("expected no eviction on zero-capacity, got %q ok=%v", key, ok)
+	}
+}
+
+func TestClock_Delete_RemovesItem(t *testing.T) {
+	clk, err := NewClockAlgorithm(2)
+	if err != nil {
+		t.Fatalf("NewClockAlgorithm error: %v", err)
+	}
+
+	clk.Set("a", 1)
+	clk.Set("b", 2)
+	clk.Delete("a")
+
+	if _, ok := clk.Get("a"); ok {
+		t.Fatalf("expected 'a' to be deleted")
+	}
+
+	// Evict should not return deleted key
+	// Loop a couple of times due to potential decrements
+	for i := 0; i < 3; i++ {
+		if key, ok := clk.Evict(); ok {
+			if key == "a" {
+				t.Fatalf("did not expect to evict deleted key 'a'")
+			}
+			if key == "b" {
+				return
+			}
+		}
+	}
+	t.Fatalf("expected to eventually evict 'b'")
+}

pkg/eviction/lfu_test.go

@@ -59,3 +59,40 @@ func TestLFU_EvictsOldestOnTie_AccessOrder(t *testing.T) {
 		t.Fatalf("expected 'b' to be evicted first on tie after accesses, got %q", key)
 	}
 }
+
+func TestLFU_ZeroCapacity_NoOp(t *testing.T) {
+	lfu, err := NewLFUAlgorithm(0)
+	if err != nil {
+		t.Fatalf("NewLFUAlgorithm error: %v", err)
+	}
+
+	lfu.Set("a", 1)
+	if _, ok := lfu.Get("a"); ok {
+		t.Fatalf("expected Get to miss on zero-capacity cache")
+	}
+
+	if key, ok := lfu.Evict(); ok || key != "" {
+		t.Fatalf("expected no eviction on zero-capacity, got %q ok=%v", key, ok)
+	}
+}
+
+func TestLFU_Delete_RemovesItem(t *testing.T) {
+	lfu, err := NewLFUAlgorithm(2)
+	if err != nil {
+		t.Fatalf("NewLFUAlgorithm error: %v", err)
+	}
+
+	lfu.Set("a", 1)
+	lfu.Set("b", 2)
+	lfu.Delete("a")
+
+	if _, ok := lfu.Get("a"); ok {
+		t.Fatalf("expected 'a' to be deleted")
+	}
+
+	// Evict should not return deleted key
+	key, ok := lfu.Evict()
+	if !ok || key != "b" {
+		t.Fatalf("expected to evict 'b' as remaining item, got %q ok=%v", key, ok)
+	}
+}

pkg/eviction/lru_test.go

@@ -48,3 +48,40 @@ func TestLRU_EvictMethodOrder(t *testing.T) {
 		t.Fatalf("expected to evict 'b' second, got %q ok=%v", key, ok)
 	}
 }
+
+func TestLRU_ZeroCapacity_NoOp(t *testing.T) {
+	lru, err := NewLRUAlgorithm(0)
+	if err != nil {
+		t.Fatalf("NewLRUAlgorithm error: %v", err)
+	}
+
+	lru.Set("a", 1)
+	if _, ok := lru.Get("a"); ok {
+		t.Fatalf("expected Get to miss on zero-capacity cache")
+	}
+
+	if key, ok := lru.Evict(); ok || key != "" {
+		t.Fatalf("expected no eviction on zero-capacity, got %q ok=%v", key, ok)
+	}
+}
+
+func TestLRU_Delete_RemovesItem(t *testing.T) {
+	lru, err := NewLRUAlgorithm(2)
+	if err != nil {
+		t.Fatalf("NewLRUAlgorithm error: %v", err)
+	}
+
+	lru.Set("a", 1)
+	lru.Set("b", 2)
+	lru.Delete("a")
+
+	if _, ok := lru.Get("a"); ok {
+		t.Fatalf("expected 'a' to be deleted")
+	}
+
+	// Evict should not return deleted key
+	key, ok := lru.Evict()
+	if !ok || key != "b" {
+		t.Fatalf("expected to evict 'b' as remaining item, got %q ok=%v", key, ok)
+	}
+}