latexgrambot: inline LaTeX bot for Telegram in Go

Renders LaTeX expressions into PNG pictures, PDF documents and native
Telegram rich text messages, entirely locally with TeX Live and poppler.

- Chat mode with /image, /pdf, /rich plus per-user preamble and DPI
- Inline mode delivering picture, PDF and rich text results
- Broad default package set preloaded into a TeX format at image build
- MongoDB persistence: settings, users, groups, render statistics
- Private S3-compatible bucket with short-lived presigned URLs
- OpenTelemetry traces over OTLP
- Kubernetes manifests and Argo CD application, Docker Compose, GitHub
  Actions CI, BSD 3-Clause license

internal/store/store_test.go

@@ -0,0 +1,55 @@
+package store
+
+import (
+	"context"
+	"os"
+	"testing"
+	"time"
+
+	"go.mongodb.org/mongo-driver/mongo"
+	"go.mongodb.org/mongo-driver/mongo/options"
+)
+
+// integrationStore connects to the cluster from MONGODB_URI (integration
+// tests only; CI runs without a database and skips them).
+func integrationStore(t *testing.T) *Store {
+	t.Helper()
+	uri := os.Getenv("MONGODB_URI")
+	if uri == "" {
+		t.Skip("MONGODB_URI not set; skipping MongoDB integration test")
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	client, err := mongo.Connect(ctx, options.Client().ApplyURI(uri))
+	if err != nil {
+		t.Fatalf("connect: %v", err)
+	}
+	t.Cleanup(func() { _ = client.Disconnect(context.Background()) })
+	if err := client.Ping(ctx, nil); err != nil {
+		t.Skipf("MongoDB not reachable, skipping integration test: %v", err)
+	}
+	return New(client, "latexgram_test_"+time.Now().Format("20060102150405"))
+}
+
+func TestSettingsRoundTrip(t *testing.T) {
+	s := integrationStore(t)
+	if got := s.Get(42); got != (Settings{}) {
+		t.Fatalf("unexpected initial settings: %+v", got)
+	}
+	settings := Settings{Preamble: `\usepackage{mhchem}`, DPI: 200}
+	if err := s.Set(42, settings); err != nil {
+		t.Fatalf("Set: %v", err)
+	}
+	if got := s.Get(42); got != settings {
+		t.Fatalf("got %+v, want %+v", got, settings)
+	}
+}
+
+func TestRecordUserAndGroup(t *testing.T) {
+	s := integrationStore(t)
+	userID := time.Now().UnixNano()
+	s.RecordUser(User{ID: userID, Username: "someone", FirstName: "A", LastName: "B"})
+	s.RecordUser(User{ID: userID})
+	s.RecordGroup(Chat{ID: -1001, Type: "supergroup", Title: "Test", Username: "test"}, true)
+	s.RecordGroup(Chat{ID: -1001}, false)
+}