Auto merge of #3669 - avborhanian:extra_results_files, r=oli-obk

Check for results files missing tests

Addresses #3572.

Basically iterates over all the files, and if it sees any files that don't have a matching rs file, it throws an error.

tests/missing-test-files.rs

@@ -0,0 +1,54 @@
+use std::fs::{self, DirEntry};
+use std::path::Path;
+
+#[test]
+fn test_missing_tests() {
+    let missing_files = explore_directory(Path::new("./tests"));
+    if !missing_files.is_empty() {
+        assert!(
+            false,
+            format!(
+                "Didn't see a test file for the following files:\n\n{}\n",
+                missing_files
+                    .iter()
+                    .map(|s| format!("\t{}", s))
+                    .collect::<Vec<_>>()
+                    .join("\n")
+            )
+        );
+    }
+}
+
+/*
+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.
+*/
+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(|e| e.path());
+    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();
+            if let Some(ext) = path.extension() {
+                match ext.to_str().unwrap() {
+                    "rs" => current_file = file_stem.clone(),
+                    "stderr" | "stdout" => {
+                        if file_stem != current_file {
+                            missing_files.push(path.to_str().unwrap().to_string());
+                        }
+                    },
+                    _ => continue,
+                };
+            }
+        }
+    }
+    missing_files
+}