✨ feat(cache): add in-memory cache service (ADR-0022 Phase 1 part 2) (#23)

Phase 1 part 2 of ADR-0022 (companion to PR #22 rate-limit). In-memory cache service via go-cache, used by /api/version (60s TTL).

6/6 unit tests pass. ~95% Mistral autonomous via ICM workspace, cost €2.50 stages 01-02 (50% reduction vs T5 thanks to pre-extracted snippets in shared/).

Co-authored-by: Gabriel Radureau <arcodange@gmail.com>
Co-committed-by: Gabriel Radureau <arcodange@gmail.com>

pkg/cache/cache_test.go

@@ -0,0 +1,135 @@
+package cache
+
+import (
+	"testing"
+	"time"
+)
+
+func TestInMemoryService_SetGet(t *testing.T) {
+	svc := NewInMemoryService(1*time.Hour, 1*time.Hour)
+
+	// Test Set and Get
+	svc.Set("key1", "value1", 1*time.Hour)
+	val, ok := svc.Get("key1")
+	if !ok {
+		t.Fatal("Expected to find key1 in cache")
+	}
+	if val != "value1" {
+		t.Fatalf("Expected 'value1', got '%v'", val)
+	}
+
+	// Test Get non-existent key
+	_, ok = svc.Get("nonexistent")
+	if ok {
+		t.Fatal("Expected not to find nonexistent key")
+	}
+}
+
+func TestInMemoryService_Delete(t *testing.T) {
+	svc := NewInMemoryService(1*time.Hour, 1*time.Hour)
+
+	svc.Set("key1", "value1", 1*time.Hour)
+	_, ok := svc.Get("key1")
+	if !ok {
+		t.Fatal("Expected to find key1 before delete")
+	}
+
+	svc.Delete("key1")
+	_, ok = svc.Get("key1")
+	if ok {
+		t.Fatal("Expected not to find key1 after delete")
+	}
+}
+
+func TestInMemoryService_Flush(t *testing.T) {
+	svc := NewInMemoryService(1*time.Hour, 1*time.Hour)
+
+	svc.Set("key1", "value1", 1*time.Hour)
+	svc.Set("key2", "value2", 1*time.Hour)
+
+	if svc.ItemCount() != 2 {
+		t.Fatalf("Expected 2 items, got %d", svc.ItemCount())
+	}
+
+	svc.Flush()
+
+	if svc.ItemCount() != 0 {
+		t.Fatalf("Expected 0 items after flush, got %d", svc.ItemCount())
+	}
+
+	_, ok := svc.Get("key1")
+	if ok {
+		t.Fatal("Expected key1 to be flushed")
+	}
+}
+
+func TestInMemoryService_ItemCount(t *testing.T) {
+	svc := NewInMemoryService(1*time.Hour, 1*time.Hour)
+
+	if svc.ItemCount() != 0 {
+		t.Fatalf("Expected 0 items initially, got %d", svc.ItemCount())
+	}
+
+	svc.Set("key1", "value1", 1*time.Hour)
+	if svc.ItemCount() != 1 {
+		t.Fatalf("Expected 1 item, got %d", svc.ItemCount())
+	}
+
+	svc.Set("key2", "value2", 1*time.Hour)
+	if svc.ItemCount() != 2 {
+		t.Fatalf("Expected 2 items, got %d", svc.ItemCount())
+	}
+
+	svc.Delete("key1")
+	if svc.ItemCount() != 1 {
+		t.Fatalf("Expected 1 item after delete, got %d", svc.ItemCount())
+	}
+}
+
+func TestInMemoryService_TTLExpiration(t *testing.T) {
+	// Use a very short TTL for testing
+	svc := NewInMemoryService(100*time.Millisecond, 50*time.Millisecond)
+
+	svc.Set("key1", "value1", 50*time.Millisecond)
+
+	// Should be present immediately
+	val, ok := svc.Get("key1")
+	if !ok {
+		t.Fatal("Expected to find key1 immediately after set")
+	}
+	if val != "value1" {
+		t.Fatalf("Expected 'value1', got '%v'", val)
+	}
+
+	// Wait for expiration
+	time.Sleep(100 * time.Millisecond)
+
+	// Should be expired now
+	_, ok = svc.Get("key1")
+	if ok {
+		t.Fatal("Expected key1 to be expired after TTL")
+	}
+}
+
+func TestInMemoryService_DifferentTypes(t *testing.T) {
+	svc := NewInMemoryService(1*time.Hour, 1*time.Hour)
+
+	// Test with different types
+	svc.Set("string", "hello", 1*time.Hour)
+	svc.Set("int", 42, 1*time.Hour)
+	svc.Set("slice", []string{"a", "b"}, 1*time.Hour)
+
+	if svc.ItemCount() != 3 {
+		t.Fatalf("Expected 3 items, got %d", svc.ItemCount())
+	}
+
+	val, ok := svc.Get("string")
+	if !ok || val != "hello" {
+		t.Fatal("String value mismatch")
+	}
+
+	val, ok = svc.Get("int")
+	if !ok || val != 42 {
+		t.Fatal("Int value mismatch")
+	}
+}