template_tests: add test example in plugin template

closes #8

plugin_template/_Cargo.toml

@@ -5,8 +5,13 @@ edition = "2021"
 publish = false
 
 [dependencies]
-serde = { version = "1", features = ["derive"] }
 picodata-plugin = "24.6.1"
+serde = { version = "1", features = ["derive"] }
+log = "0.4"
+
+[dev-dependencies]
+picodata-pike = { path = "/home/lowit/_work/picodata/cargo-pike" } # TODO: change after publish
+reqwest = { version = "0.12", features = ["blocking"] }
 
 [build-dependencies]
 liquid = "0.26"

plugin_template/tests/helpers/mod.rs

@@ -0,0 +1,63 @@
+use log::info;
+use std::{
+	fs::{self},
+	io::ErrorKind,
+	path::{Path, PathBuf},
+};
+
+// TODO: check in workspaces
+pub const TMP_DIR: &str = "tmp/";
+pub const TOPOLOGY_PATH: &str = "topology.toml";
+pub const TARGET_DIR: &str = "target";
+
+pub struct Cluster {}
+
+impl Drop for Cluster {
+	fn drop(&mut self) {
+		let data_dir = PathBuf::from(TMP_DIR.to_owned());
+		pike::cluster::stop(&data_dir).unwrap();
+	}
+}
+
+impl Cluster {
+	pub fn new() -> Cluster {
+		info!("cleaning artefacts from previous run");
+
+		match fs::remove_file(Path::new(TMP_DIR).join("instance.log")) {
+			Ok(()) => info!("Clearing logs."),
+			Err(e) if e.kind() == ErrorKind::NotFound => {
+				info!("instance.log not found, skipping cleanup");
+			},
+			Err(e) => panic!("failed to delete instance.log: {e}"),
+		}
+
+		match fs::remove_dir_all(TMP_DIR) {
+			Ok(()) => info!("clearing test plugin dir."),
+			Err(e) if e.kind() == ErrorKind::NotFound => {
+				info!("plugin dir not found, skipping cleanup");
+			},
+			Err(e) => panic!("failed to delete plugin_dir: {e}"),
+		}
+
+		Cluster {}
+	}
+}
+
+pub fn run_cluster() -> Cluster {
+	let cluster_handle = Cluster::new();
+	let data_dir = PathBuf::from(TMP_DIR.to_owned());
+	let topology_path = PathBuf::from(TOPOLOGY_PATH.to_owned());
+	let target_dir = PathBuf::from(TARGET_DIR.to_owned());
+	pike::cluster::run(
+		&topology_path,
+		&data_dir,
+		false,
+		8000,
+		&PathBuf::from("picodata".to_owned()),
+		5432,
+		false,
+        &target_dir,
+	)
+	.unwrap();
+	cluster_handle
+}

plugin_template/tests/metrics.rs

@@ -0,0 +1,11 @@
+mod helpers;
+
+use helpers::run_cluster;
+use reqwest::blocking as req;
+
+#[test]
+fn test_metrics() {
+    let _cluster_handle = run_cluster();
+    let resp = req::get("http://localhost:8001/metrics").unwrap();
+    assert!(resp.status().is_success());
+}