tests: set $HOME in a few tests to avoid depending in developer's ~/.gitignore

I just changed my `~/.gitignore` and some tests started failing
because the working copy respects the user's `~/.gitignore`. We should
probably not depend on `$HOME` in the library crate. For now, this
patch just makes sure we set it to an arbitrary directory in the tests
where it matters.

lib/src/testutils.rs

@@ -28,6 +28,14 @@ use crate::store_wrapper::StoreWrapper;
 use crate::tree::Tree;
 use crate::tree_builder::TreeBuilder;
 
+pub fn new_user_home() -> TempDir {
+    // Set $HOME to some arbitrary place so libgit2 doesn't use ~/.gitignore
+    // of the person running the tests.
+    let home_dir = tempfile::tempdir().unwrap();
+    std::env::set_var("HOME", home_dir.path());
+    home_dir
+}
+
 pub fn user_settings() -> UserSettings {
     let mut config = config::Config::new();
     config.set("user.name", "Test User").unwrap();

lib/src/working_copy.rs

@@ -288,6 +288,9 @@ impl TreeState {
     pub fn write_tree(&mut self) -> &TreeId {
         // We create a temporary git repo with the working copy shared with ours only
         // so we can use libgit2's .gitignore check.
+        // TODO: We should probably have the caller pass in the home directory to the
+        // library crate instead of depending on $HOME directly here (as we do because
+        // git2::Repository::status_should_ignore() reads the .gitignore there).
         // TODO: Do this more cleanly, perhaps by reading .gitignore files ourselves.
         let git_repo_dir = tempfile::tempdir().unwrap();
         let mut git_repo_options = RepositoryInitOptions::new();

lib/tests/test_working_copy.rs

@@ -244,7 +244,7 @@ fn test_checkout_file_transitions(use_git: bool) {
 fn test_commit_racy_timestamps(use_git: bool) {
     // Tests that file modifications are detected even if they happen the same
     // millisecond as the updated working copy state.
-
+    let _home_dir = testutils::new_user_home();
     let settings = testutils::user_settings();
     let (_temp_dir, mut repo) = testutils::init_repo(&settings, use_git);
 
@@ -274,6 +274,7 @@ fn test_commit_racy_timestamps(use_git: bool) {
 fn test_gitignores(use_git: bool) {
     // Tests that .gitignore files are respected.
 
+    let _home_dir = testutils::new_user_home();
     let settings = testutils::user_settings();
     let (_temp_dir, mut repo) = testutils::init_repo(&settings, use_git);
 

lib/tests/test_working_copy_concurrent.rs

@@ -72,6 +72,7 @@ fn test_concurrent_checkout(use_git: bool) {
 fn test_concurrent_commit(use_git: bool) {
     // Test that concurrent working copy commits result in a chain of successors
     // instead of divergence.
+    let _home_dir = testutils::new_user_home();
     let settings = testutils::user_settings();
     let (_temp_dir, mut repo1) = testutils::init_repo(&settings, use_git);
 

src/testutils.rs

@@ -15,7 +15,7 @@
 use std::io::Cursor;
 use std::path::{Path, PathBuf};
 
-use jujube_lib::testutils::user_settings;
+use jujube_lib::testutils::{new_user_home, user_settings};
 
 use crate::commands;
 use crate::ui::Ui;
@@ -34,6 +34,7 @@ impl CommandRunner {
     }
 
     pub fn run(self, mut args: Vec<&str>) -> CommandOutput {
+        let _home_dir = new_user_home();
         let mut stdout_buf = self.stdout_buf;
         let stdout = Box::new(Cursor::new(&mut stdout_buf));
         let ui = Ui::new(self.cwd, stdout, false, user_settings());