test: add unit tests and sample notes

internal/store/memory_test.go

@@ -0,0 +1,53 @@
+package store
+
+import (
+	"context"
+	"testing"
+)
+
+func TestMemoryNoteStore_CRUD(t *testing.T) {
+	s := NewMemoryNoteStore()
+	ctx := context.Background()
+
+	note := &Note{ID: "test-1", Title: "Test Note", Content: "Hello", Tags: []string{"test"}}
+	if err := s.Create(ctx, note); err != nil {
+		t.Fatalf("Create: %v", err)
+	}
+
+	got, err := s.GetByID(ctx, "test-1")
+	if err != nil {
+		t.Fatalf("GetByID: %v", err)
+	}
+	if got.Title != "Test Note" {
+		t.Errorf("Title = %q, want %q", got.Title, "Test Note")
+	}
+
+	list, err := s.List(ctx)
+	if err != nil || len(list) != 1 {
+		t.Fatalf("List: len=%d, err=%v", len(list), err)
+	}
+
+	if err := s.Delete(ctx, "test-1"); err != nil {
+		t.Fatalf("Delete: %v", err)
+	}
+	_, err = s.GetByID(ctx, "test-1")
+	if err == nil {
+		t.Fatal("expected error after delete")
+	}
+}
+
+func TestMemoryNoteStore_SearchByKeyword(t *testing.T) {
+	s := NewMemoryNoteStore()
+	ctx := context.Background()
+
+	s.Create(ctx, &Note{ID: "1", Title: "Go Concurrency", Content: "goroutine patterns"})
+	s.Create(ctx, &Note{ID: "2", Title: "Python Basics", Content: "variables and types"})
+
+	results, err := s.SearchByKeyword(ctx, "goroutine")
+	if err != nil {
+		t.Fatalf("SearchByKeyword: %v", err)
+	}
+	if len(results) != 1 || results[0].ID != "1" {
+		t.Errorf("expected 1 result with ID=1, got %d", len(results))
+	}
+}