Some tests require `ed` and fail if it is not installed

[cakebaker]

When running cargo test the following tests fail if ed is not installed:

• ed_diff::tests::test_permutations
• ed_diff::tests::test_permutations_empty_lines
• ed_diff::tests::test_permutations_reverse

They fail because they call Command::new("ed").

[oSoMoN]

The Git for Windows installer installs a number of standard Unix executables in C:\Program Files\Git\usr\bin\. Unfortunately, ed isn't one of them.

[marc-hb]

I suspect it's practically impossible for any Unix NOT to have ed. So, adding "Windows" in the name of this issue would not hurt :-)

[cakebaker]

@marc-hb I think the issue is platform-independent. Personally, I noticed it on Linux.

[marc-hb]

When running cargo test the following 3 tests fail if ed is not installed ed_diff::tests::* They fail because they call Command::new("ed").

Is this really a bug? These tests validate the output of diff --ed ... and ed is required for that.

I suspect it's practically impossible for any Unix NOT to have ed.

I think the issue is platform-independent. Personally, I noticed it on Linux.

I had a closer look and and you are right, it's much easier than I expected not to have ed on Linux:

sudo dnf remove --no-autoremove ed

Removing:
 ed          
Removing dependent packages:
 patch
 rpm-build   

So on Fedora this removes patch which is the other, much more obvious test dependency and then a lot more tests fail.

apt-get remove ed looks even easier and more likely: https://packages.debian.org/trixie/ed

[marc-hb]

BTW #226 makes the error message a bit more user-friendly, clearly mentioning the missing test dependency:

Without #226

thread 'ed_diff::tests::test_permutations_reverse' (370308) panicked at src/ed_diff.rs:399:42:
called `Result::unwrap()` on an `Err` value: Os { code: 2, kind: NotFound, message: "No such file or directory" }

With #226

thread 'ed_diff::tests::test_permutations_reverse' (385950) panicked at src/utils.rs:181:18:
Failed to start 'ed' command: Os { code: 2, kind: NotFound, message: "No such file or directory" }

(I still think this #39 is not a bug and should be closed) EDIT: except for "skipping better": #50 (comment)