wip: add preview deploy regression test

tests/test_preview_deploy.py

@@ -0,0 +1,38 @@
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parent.parent
+DOCKERFILE = ROOT / "Dockerfile.preview"
+NGINX_CONF = ROOT / "preview" / "nginx.conf"
+DOC = ROOT / "docs" / "preview-deploy.md"
+COMPOSE = ROOT / "docker-compose.yml"
+
+
+def test_preview_deploy_files_exist():
+    assert DOCKERFILE.exists(), "expected Dockerfile.preview for Nexus preview deployment"
+    assert NGINX_CONF.exists(), "expected preview/nginx.conf for Nexus preview deployment"
+    assert DOC.exists(), "expected docs/preview-deploy.md runbook"
+
+
+def test_preview_nginx_config_proxies_websocket_and_serves_modules():
+    text = NGINX_CONF.read_text(encoding="utf-8")
+    assert "listen 3000;" in text
+    assert "location /api/world/ws" in text
+    assert "proxy_pass http://nexus-main:8765;" in text
+    assert "application/javascript js;" in text
+    assert "try_files $uri $uri/ /index.html;" in text
+
+
+def test_compose_exposes_preview_service():
+    text = COMPOSE.read_text(encoding="utf-8")
+    assert "nexus-preview:" in text
+    assert '"3000:3000"' in text
+    assert "depends_on:" in text
+    assert "nexus-main" in text
+
+
+def test_preview_runbook_documents_preview_url():
+    text = DOC.read_text(encoding="utf-8")
+    assert "http://localhost:3000" in text
+    assert "docker compose up -d nexus-main nexus-preview" in text
+    assert "/api/world/ws" in text