10 files changed, 115 insertions, 53 deletions
diff --git a/library/std/src/fs/tests.rs b/library/std/src/fs/tests.rs
index 839fdc96632..909d9bf4093 100644
--- a/library/std/src/fs/tests.rs
+++ b/library/std/src/fs/tests.rs
@@ -1595,3 +1595,19 @@ fn test_read_dir_infinite_loop() {
     // Check for duplicate errors
     assert!(dir.filter(|e| e.is_err()).take(2).count() < 2);
 }
+
+#[test]
+fn rename_directory() {
+    let tmpdir = tmpdir();
+    let old_path = tmpdir.join("foo/bar/baz");
+    fs::create_dir_all(&old_path).unwrap();
+    let test_file = &old_path.join("temp.txt");
+
+    File::create(test_file).unwrap();
+
+    let new_path = tmpdir.join("quux/blat");
+    fs::create_dir_all(&new_path).unwrap();
+    fs::rename(&old_path, &new_path.join("newdir")).unwrap();
+    assert!(new_path.join("newdir").is_dir());
+    assert!(new_path.join("newdir/temp.txt").exists());
+}
diff --git a/library/std/tests/common/mod.rs b/library/std/tests/common/mod.rs
new file mode 100644
index 00000000000..fce220223a0
--- /dev/null
+++ b/library/std/tests/common/mod.rs
@@ -0,0 +1,58 @@
+#![allow(unused)]
+
+use std::env;
+use std::fs;
+use std::path::{Path, PathBuf};
+use std::thread;
+use rand::RngCore;
+
+/// Copied from `std::test_helpers::test_rng`, since these tests rely on the
+/// seed not being the same for every RNG invocation too.
+#[track_caller]
+pub(crate) fn test_rng() -> rand_xorshift::XorShiftRng {
+    use core::hash::{BuildHasher, Hash, Hasher};
+    let mut hasher = std::collections::hash_map::RandomState::new().build_hasher();
+    core::panic::Location::caller().hash(&mut hasher);
+    let hc64 = hasher.finish();
+    let seed_vec = hc64.to_le_bytes().into_iter().chain(0u8..8).collect::<Vec<u8>>();
+    let seed: [u8; 16] = seed_vec.as_slice().try_into().unwrap();
+    rand::SeedableRng::from_seed(seed)
+}
+
+// Copied from std::sys_common::io
+pub struct TempDir(PathBuf);
+
+impl TempDir {
+    pub fn join(&self, path: &str) -> PathBuf {
+        let TempDir(ref p) = *self;
+        p.join(path)
+    }
+
+    pub fn path(&self) -> &Path {
+        let TempDir(ref p) = *self;
+        p
+    }
+}
+
+impl Drop for TempDir {
+    fn drop(&mut self) {
+        // Gee, seeing how we're testing the fs module I sure hope that we
+        // at least implement this correctly!
+        let TempDir(ref p) = *self;
+        let result = fs::remove_dir_all(p);
+        // Avoid panicking while panicking as this causes the process to
+        // immediately abort, without displaying test results.
+        if !thread::panicking() {
+            result.unwrap();
+        }
+    }
+}
+
+#[track_caller] // for `test_rng`
+pub fn tmpdir() -> TempDir {
+    let p = env::temp_dir();
+    let mut r = test_rng();
+    let ret = p.join(&format!("rust-{}", r.next_u32()));
+    fs::create_dir(&ret).unwrap();
+    TempDir(ret)
+}
diff --git a/library/std/tests/create_dir_all_bare.rs b/library/std/tests/create_dir_all_bare.rs
new file mode 100644
index 00000000000..fe789323f97
--- /dev/null
+++ b/library/std/tests/create_dir_all_bare.rs
@@ -0,0 +1,39 @@
+#![cfg(all(test, not(any(target_os = "emscripten", target_env = "sgx"))))]
+
+//! Note that this test changes the current directory so
+//! should not be in the same process as other tests.
+use std::env;
+use std::fs;
+use std::path::{Path, PathBuf};
+
+mod common;
+
+// On some platforms, setting the current directory will prevent deleting it.
+// So this helper ensures the current directory is reset.
+struct CurrentDir(PathBuf);
+impl CurrentDir {
+    fn new() -> Self {
+        Self(env::current_dir().unwrap())
+    }
+    fn set(&self, path: &Path) {
+        env::set_current_dir(path).unwrap();
+    }
+    fn with(path: &Path, f: impl FnOnce()) {
+        let current_dir = Self::new();
+        current_dir.set(path);
+        f();
+    }
+}
+impl Drop for CurrentDir {
+    fn drop(&mut self) {
+        env::set_current_dir(&self.0).unwrap();
+    }
+}
+
+#[test]
+fn create_dir_all_bare() {
+    let tmpdir = common::tmpdir();
+    CurrentDir::with(tmpdir.path(), || {
+        fs::create_dir_all("create-dir-all-bare").unwrap();
+    });
+}
diff --git a/library/std/tests/env.rs b/library/std/tests/env.rs
index aae2c49d898..96b4f372b8b 100644
--- a/library/std/tests/env.rs
+++ b/library/std/tests/env.rs
@@ -3,18 +3,8 @@ use std::ffi::{OsStr, OsString};
 
 use rand::distributions::{Alphanumeric, DistString};
 
-/// Copied from `std::test_helpers::test_rng`, since these tests rely on the
-/// seed not being the same for every RNG invocation too.
-#[track_caller]
-pub(crate) fn test_rng() -> rand_xorshift::XorShiftRng {
-    use core::hash::{BuildHasher, Hash, Hasher};
-    let mut hasher = std::collections::hash_map::RandomState::new().build_hasher();
-    core::panic::Location::caller().hash(&mut hasher);
-    let hc64 = hasher.finish();
-    let seed_vec = hc64.to_le_bytes().into_iter().chain(0u8..8).collect::<Vec<u8>>();
-    let seed: [u8; 16] = seed_vec.as_slice().try_into().unwrap();
-    rand::SeedableRng::from_seed(seed)
-}
+mod common;
+use common::test_rng;
 
 #[track_caller]
 fn make_rand_name() -> OsString {
diff --git a/tests/ui-fulldeps/create-dir-all-bare.rs b/tests/ui-fulldeps/create-dir-all-bare.rs
deleted file mode 100644
index 4554680ec24..00000000000
--- a/tests/ui-fulldeps/create-dir-all-bare.rs
+++ /dev/null
@@ -1,11 +0,0 @@
-// run-pass
-
-use std::env;
-use std::fs;
-use std::path::PathBuf;
-
-fn main() {
-    let path = PathBuf::from(env::var_os("RUST_TEST_TMPDIR").unwrap());
-    env::set_current_dir(&path).unwrap();
-    fs::create_dir_all("create-dir-all-bare").unwrap();
-}
diff --git a/tests/ui-fulldeps/rename-directory.rs b/tests/ui-fulldeps/rename-directory.rs
deleted file mode 100644
index 8fc340cb918..00000000000
--- a/tests/ui-fulldeps/rename-directory.rs
+++ /dev/null
@@ -1,30 +0,0 @@
-// run-pass
-
-#![allow(unused_must_use)]
-#![allow(unused_imports)]
-// This test can't be a unit test in std,
-// because it needs TempDir, which is in extra
-
-// ignore-cross-compile
-
-use std::env;
-use std::ffi::CString;
-use std::fs::{self, File};
-use std::path::PathBuf;
-
-fn rename_directory() {
-    let tmpdir = PathBuf::from(env::var_os("RUST_TEST_TMPDIR").unwrap());
-    let old_path = tmpdir.join("foo/bar/baz");
-    fs::create_dir_all(&old_path).unwrap();
-    let test_file = &old_path.join("temp.txt");
-
-    File::create(test_file).unwrap();
-
-    let new_path = tmpdir.join("quux/blat");
-    fs::create_dir_all(&new_path).unwrap();
-    fs::rename(&old_path, &new_path.join("newdir"));
-    assert!(new_path.join("newdir").is_dir());
-    assert!(new_path.join("newdir/temp.txt").exists());
-}
-
-pub fn main() { rename_directory() }
diff --git a/tests/ui-fulldeps/issue-15149.rs b/tests/ui-fulldeps/std/issue-15149.rs
index 064472f5785..064472f5785 100644
--- a/tests/ui-fulldeps/issue-15149.rs
+++ b/tests/ui-fulldeps/std/issue-15149.rs
diff --git a/tests/ui-fulldeps/issue-81357-unsound-file-methods.rs b/tests/ui-fulldeps/std/issue-81357-unsound-file-methods.rs
index fdf1150f8d2..fdf1150f8d2 100644
--- a/tests/ui-fulldeps/issue-81357-unsound-file-methods.rs
+++ b/tests/ui-fulldeps/std/issue-81357-unsound-file-methods.rs
diff --git a/tests/ui-fulldeps/stdio-from.rs b/tests/ui-fulldeps/std/stdio-from.rs
index fef9f27fcdf..fef9f27fcdf 100644
--- a/tests/ui-fulldeps/stdio-from.rs
+++ b/tests/ui-fulldeps/std/stdio-from.rs
diff --git a/tests/ui-fulldeps/switch-stdout.rs b/tests/ui-fulldeps/std/switch-stdout.rs
index e9501a80930..e9501a80930 100644
--- a/tests/ui-fulldeps/switch-stdout.rs
+++ b/tests/ui-fulldeps/std/switch-stdout.rs