Account for revisions in missing-test-files

tests/missing-test-files.rs

@@ -1,7 +1,10 @@
 #![cfg_attr(feature = "deny-warnings", deny(warnings))]
 #![warn(rust_2018_idioms, unused_lifetimes)]
 #![allow(clippy::assertions_on_constants)]
+#![feature(path_file_prefix)]
 
+use std::cmp::Ordering;
+use std::ffi::OsStr;
 use std::fs::{self, DirEntry};
 use std::path::Path;
 
@@ -21,29 +24,39 @@ fn test_missing_tests() {
     }
 }
 
-/*
-Test for missing files.
-
-Since rs files are alphabetically before stderr/stdout, we can sort by the full name
-and iter in that order. If we've seen the file stem for the first time and it's not
-a rust file, it means the rust file has to be missing.
-*/
+// Test for missing files.
 fn explore_directory(dir: &Path) -> Vec<String> {
     let mut missing_files: Vec<String> = Vec::new();
     let mut current_file = String::new();
     let mut files: Vec<DirEntry> = fs::read_dir(dir).unwrap().filter_map(Result::ok).collect();
-    files.sort_by_key(std::fs::DirEntry::path);
+    files.sort_by(|x, y| {
+        match x.path().file_prefix().cmp(&y.path().file_prefix()) {
+            Ordering::Equal => (),
+            ord => return ord,
+        }
+        // Sort rs files before the others if they share the same prefix. So when we see
+        // the file prefix for the first time and it's not a rust file, it means the rust
+        // file has to be missing.
+        match (
+            x.path().extension().and_then(OsStr::to_str),
+            y.path().extension().and_then(OsStr::to_str),
+        ) {
+            (Some("rs"), _) => Ordering::Less,
+            (_, Some("rs")) => Ordering::Greater,
+            _ => Ordering::Equal,
+        }
+    });
     for entry in &files {
         let path = entry.path();
         if path.is_dir() {
             missing_files.extend(explore_directory(&path));
         } else {
-            let file_stem = path.file_stem().unwrap().to_str().unwrap().to_string();
+            let file_prefix = path.file_prefix().unwrap().to_str().unwrap().to_string();
             if let Some(ext) = path.extension() {
                 match ext.to_str().unwrap() {
-                    "rs" => current_file = file_stem.clone(),
+                    "rs" => current_file = file_prefix.clone(),
                     "stderr" | "stdout" => {
-                        if file_stem != current_file {
+                        if file_prefix != current_file {
                             missing_files.push(path.to_str().unwrap().to_string());
                         }
                     },