readme_test's direct invocation of rustdoc --test is fragile

[jamessan]

Debian's environment for packaging Rust crates uses a local crate registry and some other adaptations to ensure the builds are self-contained. This is causing readme_test to fail because it doesn't find the transitive vte_generate_state_changes dependency.

The normal doctests work fine, because those still go through the cargo wrapper that Debian is using.

If/when it's reasonable to raise strip-ansi-escape's minimum Rust version to 1.54 (for the include_str! macro), the manual rustdoc invocation could be replaced as below which will also address the problem:

diff --git i/src/lib.rs w/src/lib.rs
index 915494e..53acb97 100644
--- i/src/lib.rs
+++ w/src/lib.rs
@@ -151,42 +151,14 @@ where
     }
 }
 
+#[doc = include_str!("../README.md")]
+#[cfg(doctest)]
+pub struct ReadmeDoctests;
+
 #[cfg(test)]
 mod tests {
     use super::*;
 
-    use std::env;
-    use std::env::consts::EXE_EXTENSION;
-    use std::path::Path;
-    use std::process::Command;
-
-    #[test]
-    fn readme_test() {
-        let rustdoc = Path::new("rustdoc").with_extension(EXE_EXTENSION);
-        let readme = Path::new(file!())
-            .parent()
-            .unwrap()
-            .parent()
-            .unwrap()
-            .join("README.md");
-        let exe = env::current_exe().unwrap();
-        let outdir = exe.parent().unwrap();
-        let mut cmd = Command::new(rustdoc);
-        cmd.args(&["--verbose", "--test", "-L"])
-            .arg(&outdir)
-            .arg(&readme);
-        println!("{:?}", cmd);
-        let result = cmd
-            .spawn()
-            .expect("Failed to spawn process")
-            .wait()
-            .expect("Failed to run process");
-        assert!(
-            result.success(),
-            "Failed to run rustdoc tests on README.md!"
-        );
-    }
-
     fn assert_parsed(input: &[u8], expected: &[u8]) {
         let bytes = strip(input).expect("Failed to strip escapes");
         assert_eq!(bytes, expected);

For now, I'm just skipping readme_test in our builds.

[luser]

Yeah, I fumbled around looking for a better solution to this for a while once I stopped using the skeptic crate. In recent months I've started switching my Rust crates over to use the doc_comment crate, which is a much cleaner solution.

For example: https://github.com/luser/rust-test-assembler/blob/3a69aa2832f7aa991c62219f3f4b5ecc603084d9/src/lib.rs#L79

I'd merge that PR if someone wants to do the work, otherwise I'll get around to it eventually.