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/config/config_test.go

@@ -0,0 +1,143 @@
+package config
+
+import (
+	"strings"
+	"testing"
+	"time"
+)
+
+func setRequired(t *testing.T) {
+	t.Helper()
+	t.Setenv("TELEGRAM_BOT_TOKEN", "123:abc")
+	t.Setenv("MONGODB_URI", "mongodb://example:27017")
+}
+
+func TestLoadDefaults(t *testing.T) {
+	setRequired(t)
+	cfg, err := Load()
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	if cfg.RenderDPI != 600 {
+		t.Errorf("RenderDPI = %d, want 600", cfg.RenderDPI)
+	}
+	if cfg.RenderTimeout != 30*time.Second {
+		t.Errorf("RenderTimeout = %s, want 30s", cfg.RenderTimeout)
+	}
+	if cfg.MaxConcurrency != 2 {
+		t.Errorf("MaxConcurrency = %d, want 2", cfg.MaxConcurrency)
+	}
+	if cfg.MaxExpressionLen != 4000 || cfg.MaxPreambleLen != 4000 {
+		t.Errorf("unexpected length caps: %d/%d", cfg.MaxExpressionLen, cfg.MaxPreambleLen)
+	}
+	if cfg.HealthAddr != ":8080" {
+		t.Errorf("HealthAddr = %q, want :8080", cfg.HealthAddr)
+	}
+	if cfg.MongoDatabase != "latexgram" {
+		t.Errorf("MongoDatabase = %q, want latexgram", cfg.MongoDatabase)
+	}
+	if !cfg.RichTextEnabled {
+		t.Error("RichTextEnabled = false, want true by default")
+	}
+	if !cfg.RichDefaultMath {
+		t.Error("RichDefaultMath = false, want true by default")
+	}
+	if cfg.S3PresignTTL != time.Hour {
+		t.Errorf("S3PresignTTL = %s, want 1h", cfg.S3PresignTTL)
+	}
+	if cfg.S3Enabled() {
+		t.Error("S3Enabled = true without S3 configuration")
+	}
+}
+
+func TestLoadS3(t *testing.T) {
+	setRequired(t)
+	t.Setenv("S3_ENDPOINT_URL", "http://minio:9000/")
+	t.Setenv("S3_BUCKET", "latexgrambot")
+	t.Setenv("AWS_ACCESS_KEY_ID", "access")
+	t.Setenv("AWS_SECRET_ACCESS_KEY", "secret")
+	t.Setenv("S3_PUBLIC_ENDPOINT_URL", "https://s3.example/")
+	t.Setenv("S3_PRESIGN_TTL", "45m")
+	cfg, err := Load()
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	if !cfg.S3Enabled() || cfg.S3Endpoint != "http://minio:9000" || cfg.S3PublicEndpoint != "https://s3.example" {
+		t.Fatalf("unexpected S3 config: %+v", cfg)
+	}
+	if cfg.S3PresignTTL != 45*time.Minute {
+		t.Errorf("S3PresignTTL = %s", cfg.S3PresignTTL)
+	}
+}
+
+func TestLoadRejectsIncompleteS3(t *testing.T) {
+	setRequired(t)
+	t.Setenv("S3_BUCKET", "latexgrambot")
+	if _, err := Load(); err == nil || !strings.Contains(err.Error(), "incomplete S3 configuration") {
+		t.Fatalf("expected incomplete S3 error, got %v", err)
+	}
+}
+
+func TestLoadRichDefaultMathToggle(t *testing.T) {
+	setRequired(t)
+	t.Setenv("RICH_DEFAULT_MATH", "false")
+	cfg, err := Load()
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	if cfg.RichDefaultMath {
+		t.Error("RichDefaultMath = true, want false")
+	}
+
+	t.Setenv("RICH_DEFAULT_MATH", "banana")
+	if _, err := Load(); err == nil || !strings.Contains(err.Error(), "RICH_DEFAULT_MATH") {
+		t.Fatalf("expected RICH_DEFAULT_MATH validation error, got %v", err)
+	}
+}
+
+func TestLoadRichTextToggle(t *testing.T) {
+	setRequired(t)
+	t.Setenv("RICH_TEXT_ENABLED", "false")
+	cfg, err := Load()
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	if cfg.RichTextEnabled {
+		t.Error("RichTextEnabled = true, want false")
+	}
+
+	t.Setenv("RICH_TEXT_ENABLED", "banana")
+	if _, err := Load(); err == nil || !strings.Contains(err.Error(), "RICH_TEXT_ENABLED") {
+		t.Fatalf("expected RICH_TEXT_ENABLED validation error, got %v", err)
+	}
+}
+
+func TestLoadMissingToken(t *testing.T) {
+	t.Setenv("MONGODB_URI", "mongodb://example:27017")
+	_, err := Load()
+	if err == nil || !strings.Contains(err.Error(), "TELEGRAM_BOT_TOKEN") {
+		t.Fatalf("expected missing token error, got %v", err)
+	}
+}
+
+func TestLoadMissingMongoURI(t *testing.T) {
+	t.Setenv("TELEGRAM_BOT_TOKEN", "123:abc")
+	_, err := Load()
+	if err == nil || !strings.Contains(err.Error(), "MONGODB_URI") {
+		t.Fatalf("expected missing MONGODB_URI error, got %v", err)
+	}
+}
+
+func TestLoadInvalidValues(t *testing.T) {
+	setRequired(t)
+	t.Setenv("RENDER_DPI", "10")
+	if _, err := Load(); err == nil || !strings.Contains(err.Error(), "RENDER_DPI") {
+		t.Fatalf("expected RENDER_DPI validation error, got %v", err)
+	}
+
+	t.Setenv("RENDER_DPI", "300")
+	t.Setenv("RENDER_TIMEOUT", "banana")
+	if _, err := Load(); err == nil || !strings.Contains(err.Error(), "RENDER_TIMEOUT") {
+		t.Fatalf("expected RENDER_TIMEOUT validation error, got %v", err)
+	}
+}