cli: fix git-colocated working copy on Windows

This patch adds a very simple e2e test of having a working copy shared
with Git. The test initially failed on Windows. The symptom was that
the "master" branch did not get updated when we create a commit using
`jj`. That suggested that we didn't correctly detect that the working
copy was shared. After a lot of troubleshooting, I think I mostly
understand what we going on here (thanks to @arxanas for suggesting
https://github.com/mxschmitt/action-tmate). The path we get from
`git2::Repository::workdir()` seems to not be canonicalized in the
same way as `std::fs::canonicalize()` canonicalizes. Specifically, it
does not have the "\\?\" prefix we get from that function. I suppose
that's because libgit2 is a C library and canonicalizes the path using
some other system call.

CHANGELOG.md

@@ -41,6 +41,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 * `jj log` now accepts `-p`/`--patch` option.
 
+### Fixed bugs
+
+* When sharing the working copy with a Git repo, the automatic importing and
+  exporting (sometimes?) didn't happen on Windows.
+
 ## [0.3.3] - 2022-03-16
 
 No changes, only trying to get the automated build to work.

src/commands.rs

@@ -292,9 +292,12 @@ impl WorkspaceCommandHelper {
         let may_update_working_copy = loaded_at_head && !root_args.no_commit_working_copy;
         let mut working_copy_shared_with_git = false;
         let maybe_git_repo = repo.store().git_repo();
-        if let Some(git_repo) = &maybe_git_repo {
-            working_copy_shared_with_git =
-                git_repo.workdir() == Some(workspace.workspace_root().as_path());
+        if let Some(git_workdir) = maybe_git_repo
+            .as_ref()
+            .and_then(|git_repo| git_repo.workdir())
+            .and_then(|workdir| workdir.canonicalize().ok())
+        {
+            working_copy_shared_with_git = git_workdir == workspace.workspace_root().as_path();
         }
         let mut helper = Self {
             string_args,

tests/test_git_colocated.rs

@@ -0,0 +1,38 @@
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use jujutsu::testutils::TestEnvironment;
+
+#[test]
+fn test_git_colocated() {
+    let test_env = TestEnvironment::default();
+    let workspace_root = test_env.env_root().join("repo");
+    let git_repo = git2::Repository::init(&workspace_root).unwrap();
+    test_env.jj_cmd_success(&workspace_root, &["init", "--git-repo", "."]);
+
+    // Create a commit from jj and check that it's reflected in git
+    std::fs::write(workspace_root.join("new-file"), "contents").unwrap();
+    test_env.jj_cmd_success(&workspace_root, &["close", "-m", "add a file"]);
+    let stdout =
+        test_env.jj_cmd_success(&workspace_root, &["log", "-T", "commit_id \" \" branches"]);
+    insta::assert_snapshot!(stdout, @r###"
+    @ 2588800a4ee68926773f1e9c44dcc50ada923650 
+    o 172b1cbfe88c97cbd1b1c8a98a48e729a4540e85 master
+    o 0000000000000000000000000000000000000000 
+    "###);
+    assert_eq!(
+        git_repo.head().unwrap().target().unwrap().to_string(),
+        "172b1cbfe88c97cbd1b1c8a98a48e729a4540e85".to_string()
+    );
+}