From fdd103b31b4d27f84a4d07d1b6994352d451a2d2 Mon Sep 17 00:00:00 2001
From: Mark Thomas <mbthomas@fb.com>
Date: Tue, 26 Mar 2019 07:30:25 -0700
Subject: [PATCH] configparser: avoid environment race in configparser tests

Summary:
The configparser tests `hg::tests::test_basic_hgplain` and
`hg::tests::test_hgplainexcept` set different values for `HGPLAIN` and
`HGPLAINEXCEPT`.  Since the tests run in parallel and use the same environment,
one of the tests may fail if they run at the same time.

For these tests, create a mutex for the environment and lock it for the
duration of the test, ensuring these tests do not interfere with each other.

Reviewed By: jsgf

Differential Revision: D14615394

fbshipit-source-id: 9f123668d93223655514db2ae34b05354a6b578c
---
 lib/configparser/Cargo.toml |  1 +
 lib/configparser/src/hg.rs  | 11 +++++++++++
 2 files changed, 12 insertions(+)

diff --git a/lib/configparser/Cargo.toml b/lib/configparser/Cargo.toml
index 0245c40556..a2edac7b04 100644
--- a/lib/configparser/Cargo.toml
+++ b/lib/configparser/Cargo.toml
@@ -14,6 +14,7 @@ pest_derive = "2.1.0"
 shellexpand = "1.0.0"
 
 [dev-dependencies]
+lazy_static = "1.3.0"
 minibench = { path = "../minibench" }
 tempdir = "0.3.7"
 
diff --git a/lib/configparser/src/hg.rs b/lib/configparser/src/hg.rs
index 4928b1bf62..e7d2e0068e 100644
--- a/lib/configparser/src/hg.rs
+++ b/lib/configparser/src/hg.rs
@@ -514,8 +514,18 @@ mod tests {
 
     use crate::config::tests::write_file;
 
+    use lazy_static::lazy_static;
+    use std::sync::Mutex;
+
+    lazy_static! {
+        /// Lock for the environment.  This should be acquired by tests that rely on particular
+        /// environment variable values that might be overwritten by other tests.
+        static ref ENV_LOCK: Mutex<()> = Mutex::new(());
+    }
+
     #[test]
     fn test_basic_hgplain() {
+        let _guard = ENV_LOCK.lock().unwrap();
         env::set_var(HGPLAIN, "1");
         env::remove_var(HGPLAINEXCEPT);
 
@@ -540,6 +550,7 @@ mod tests {
 
     #[test]
     fn test_hgplainexcept() {
+        let _guard = ENV_LOCK.lock().unwrap();
         env::remove_var(HGPLAIN);
         env::set_var(HGPLAINEXCEPT, "alias,revsetalias");