replace tempdir by tempfile (#2143)

## Issue Addressed

Fixes #2141 
Remove [tempdir](https://docs.rs/tempdir/0.3.7/tempdir/) in favor of [tempfile](https://docs.rs/tempfile/3.1.0/tempfile/).

## Proposed Changes

`tempfile` has a slightly different api that makes creating temp folders with a name prefix a chore (`tempdir::TempDir::new("toto")` => `tempfile::Builder::new().prefix("toto").tempdir()`).

So I removed temp folder name prefix where I deemed it not useful.

Otherwise, the functionality is the same.

testing/node_test_rig/Cargo.toml

@@ -9,7 +9,7 @@ environment = { path = "../../lighthouse/environment" }
 beacon_node = { path = "../../beacon_node" }
 types = { path = "../../consensus/types" }
 eth2_config = { path = "../../common/eth2_config" }
-tempdir = "0.3.7"
+tempfile = "3.1.0"
 reqwest = { version = "0.10.8", features = ["native-tls-vendored"] }
 url = "2.1.1"
 serde = "1.0.116"

testing/node_test_rig/src/lib.rs

@@ -11,7 +11,7 @@ use eth2::{
 use std::path::PathBuf;
 use std::time::Duration;
 use std::time::{SystemTime, UNIX_EPOCH};
-use tempdir::TempDir;
+use tempfile::{Builder as TempBuilder, TempDir};
 use types::EthSpec;
 use validator_client::ProductionValidatorClient;
 use validator_dir::insecure_keys::build_deterministic_validator_dirs;
@@ -42,7 +42,9 @@ impl<E: EthSpec> LocalBeaconNode<E> {
         mut client_config: ClientConfig,
     ) -> Result<Self, String> {
         // Creates a temporary directory that will be deleted once this `TempDir` is dropped.
-        let datadir = TempDir::new("lighthouse_node_test_rig")
+        let datadir = TempBuilder::new()
+            .prefix("lighthouse_node_test_rig")
+            .tempdir()
             .expect("should create temp directory for client datadir");
 
         client_config.data_dir = datadir.path().into();
@@ -125,10 +127,14 @@ pub struct ValidatorFiles {
 impl ValidatorFiles {
     /// Creates temporary data and secrets dirs.
     pub fn new() -> Result<Self, String> {
-        let datadir = TempDir::new("lighthouse-validator-client")
+        let datadir = TempBuilder::new()
+            .prefix("lighthouse-validator-client")
+            .tempdir()
             .map_err(|e| format!("Unable to create VC data dir: {:?}", e))?;
 
-        let secrets_dir = TempDir::new("lighthouse-validator-client-secrets")
+        let secrets_dir = TempBuilder::new()
+            .prefix("lighthouse-validator-client-secrets")
+            .tempdir()
             .map_err(|e| format!("Unable to create VC secrets dir: {:?}", e))?;
 
         Ok(Self {

testing/remote_signer_test/Cargo.toml

@@ -14,7 +14,7 @@ remote_signer_consumer = { path = "../../common/remote_signer_consumer" }
 reqwest = { version = "0.10.8", features = ["blocking", "json"] }
 serde = { version = "1.0.116", features = ["derive"] }
 serde_json = "1.0.58"
-tempdir = "0.3.7"
+tempfile = "3.1.0"
 tokio = { version = "0.3.5", features = ["time"] }
 types = { path = "../../consensus/types" }
 tokio-compat-02 = "0.1"

testing/remote_signer_test/src/api_test_signer.rs

@@ -5,7 +5,7 @@ pub use local_signer_test_data::*;
 use remote_signer_client::Client;
 use serde_json::Value;
 use std::collections::HashMap;
-use tempdir::TempDir;
+use tempfile::{Builder as TempBuilder, TempDir};
 use types::EthSpec;
 
 pub struct ApiTestSigner<E: EthSpec> {
@@ -81,7 +81,10 @@ pub fn get_environment(is_log_active: bool) -> Environment<E> {
 }
 
 pub fn set_up_api_test_signer_raw_dir() -> (ApiTestSigner<E>, TempDir) {
-    let tmp_dir = TempDir::new("bls-remote-signer-test").unwrap();
+    let tmp_dir = TempBuilder::new()
+        .prefix("bls-remote-signer-test")
+        .tempdir()
+        .unwrap();
     let arg_vec = vec![
         "this_test",
         "--port",

testing/remote_signer_test/src/utils.rs

@@ -11,7 +11,7 @@ use std::io::Write;
 use std::net::IpAddr::{V4, V6};
 use std::os::unix::fs::PermissionsExt;
 use std::path::Path;
-use tempdir::TempDir;
+use tempfile::TempDir;
 use types::{
     AggregateSignature, Attestation, AttestationData, AttesterSlashing, BeaconBlock,
     BeaconBlockHeader, BitList, Checkpoint, Deposit, DepositData, Epoch, EthSpec, FixedVector,