End-to-end unit test (#90)

* First implementation of create_torrent_file

* Test harness for e2e preparing

* Saving

* Continuing test harness

* Continuing test harness

* Continuing test harness

* All servers are running

* Full e2e harness done

* Test e2e harness working fine

* Remove lints

* injecting faults

* The e2e test runs continuously

* e2e test

* Add a test for create_torrent

* Nothing

* Nothing, just tweaking the numberes

* Update tokio, remove custom tempfile shim

crates/librqbit/src/tests/test_util.rs

@@ -0,0 +1,66 @@
+use std::{io::Write, path::Path};
+
+use librqbit_core::Id20;
+use rand::RngCore;
+use tempfile::TempDir;
+
+pub fn create_new_file_with_random_content(path: &Path, mut size: usize) {
+    let mut file = std::fs::OpenOptions::new()
+        .create_new(true)
+        .write(true)
+        .open(path)
+        .unwrap();
+
+    eprintln!("creating temp file {:?}", path);
+
+    const BUF_SIZE: usize = 8192 * 16;
+    let mut rng = rand::rngs::OsRng;
+    let mut write_buf = [0; BUF_SIZE];
+    while size > 0 {
+        rng.fill_bytes(&mut write_buf[..]);
+        let written = file.write(&write_buf[..size.min(BUF_SIZE)]).unwrap();
+        size -= written;
+    }
+}
+
+pub fn create_default_random_dir_with_torrents(
+    num_files: usize,
+    file_size: usize,
+    tempdir_prefix: Option<&str>,
+) -> TempDir {
+    let dir = TempDir::with_prefix(tempdir_prefix.unwrap_or("rqbit_test")).unwrap();
+    dbg!(dir.path());
+    for f in 0..num_files {
+        create_new_file_with_random_content(&dir.path().join(&format!("{f}.data")), file_size);
+    }
+    dir
+}
+
+#[derive(Debug)]
+pub struct TestPeerMetadata {
+    pub server_id: u8,
+    pub max_random_sleep_ms: u8,
+}
+
+impl TestPeerMetadata {
+    pub fn as_peer_id(&self) -> Id20 {
+        let mut peer_id = Id20::default();
+        peer_id.0[0] = self.server_id;
+        peer_id.0[1] = self.max_random_sleep_ms;
+        peer_id
+    }
+
+    pub fn from_peer_id(peer_id: Id20) -> Self {
+        Self {
+            server_id: peer_id.0[0],
+            max_random_sleep_ms: peer_id.0[1],
+        }
+    }
+
+    pub fn disconnect_probability(&self) -> f64 {
+        if self.server_id % 2 == 0 {
+            return 0.05f64;
+        }
+        0f64
+    }
+}