Struct assert_fs::NamedTempFile

source · 
pub struct NamedTempFile { /* private fields */ }
Expand description

A potential file in the filesystem that is automatically deleted when it goes out of scope.

The NamedTempFile type creates a directory on the file system that is deleted once it goes out of scope. At construction, the NamedTempFile creates a new directory with a randomly generated name.

The constructor, [NamedTempFile::new(name)], creates directories in the location returned by std::env::temp_dir().

After creating a NamedTempFile, work with the file system by doing standard std::fs file system operations on its Path, which can be retrieved with NamedTempFile::path(). Once the NamedTempFile value is dropped, the parent directory will be deleted, along with the file. It is your responsibility to ensure that no further file system operations are attempted inside the temporary directory once it has been deleted.

Resource Leaking

Various platform-specific conditions may cause NamedTempFile to fail to delete the underlying directory. It’s important to ensure that handles (like File and ReadDir) to the file inside the directory is dropped before the NamedTempFile goes out of scope. The NamedTempFile destructor will silently ignore any errors in deleting the directory; to instead handle errors call NamedTempFile::close().

Note that if the program exits before the NamedTempFile destructor is run, such as via std::process::exit(), by segfaulting, or by receiving a signal like SIGINT, then the temporary directory will not be deleted.

Examples

Create a temporary file.

use assert_fs::fixture::NamedTempFile;

let tmp_file = NamedTempFile::new("foo.rs").unwrap();

// Ensure deletion happens.
tmp_file.close().unwrap();

Implementations§

Attempts to make a temporary file inside of env::temp_dir().

The file and parent directory will be automatically deleted once the returned NamedTempFile is destroyed.

Errors

If the parent directory can not be created, Err is returned.

Examples
use assert_fs::fixture::NamedTempFile;

let tmp_file = NamedTempFile::new("foo.rs").unwrap();

// Ensure deletion happens.
tmp_file.close().unwrap();

Conditionally persist the temporary file for debug purposes.

Note: this operation is not reversible, i.e. into_persistent_if(false) is a no-op.

Examples
use assert_fs::fixture::NamedTempFile;

let tmp_file = NamedTempFile::new("foo.rs")
    .unwrap()
    .into_persistent_if(std::env::var_os("TEST_PERSIST_FILES").is_some());

// Ensure deletion happens.
tmp_file.close().unwrap();

Persist the temporary file for debug purposes.

Note: this operation is not reversible, i.e. into_persistent_if(false) is a no-op.

Examples
use assert_fs::fixture::NamedTempFile;

let tmp_file = NamedTempFile::new("foo.rs")
    .unwrap()
    .into_persistent();

// Ensure deletion happens.
tmp_file.close().unwrap();

Accesses the Path to the temporary file.

Examples
use assert_fs::fixture::NamedTempFile;

let tmp_file = NamedTempFile::new("foo.rs").unwrap();

println!("{}", tmp_file.path().display());

// Ensure deletion happens.
tmp_file.close().unwrap();

Closes and removes the temporary file and parent directory, returning a Result.

Although NamedTempFile removes the directory on drop, in the destructor any errors are ignored. To detect errors cleaning up the temporary directory, call close instead.

Errors

This function may return a variety of std::io::Errors that result from deleting the temporary file and parent directory, These errors may be platform specific.

Examples
use assert_fs::fixture::NamedTempFile;

let tmp_file = NamedTempFile::new("foo.rs").unwrap();

// Ensure deletion happens.
tmp_file.close().unwrap();

Methods from Deref<Target = Path>§

Yields the underlying OsStr slice.

Examples
use std::path::Path;

let os_str = Path::new("foo.txt").as_os_str();
assert_eq!(os_str, std::ffi::OsStr::new("foo.txt"));

Yields a &str slice if the Path is valid unicode.

This conversion may entail doing a check for UTF-8 validity. Note that validation is performed because non-UTF-8 strings are perfectly valid for some OS.

Examples
use std::path::Path;

let path = Path::new("foo.txt");
assert_eq!(path.to_str(), Some("foo.txt"));

Converts a Path to a Cow<str>.

Any non-Unicode sequences are replaced with U+FFFD REPLACEMENT CHARACTER.

Examples

Calling to_string_lossy on a Path with valid unicode:

use std::path::Path;

let path = Path::new("foo.txt");
assert_eq!(path.to_string_lossy(), "foo.txt");

Had path contained invalid unicode, the to_string_lossy call might have returned "fo�.txt".

Converts a Path to an owned PathBuf.

Examples
use std::path::Path;

let path_buf = Path::new("foo.txt").to_path_buf();
assert_eq!(path_buf, std::path::PathBuf::from("foo.txt"));

Returns true if the Path is absolute, i.e., if it is independent of the current directory.

  • On Unix, a path is absolute if it starts with the root, so is_absolute and has_root are equivalent.

  • On Windows, a path is absolute if it has a prefix and starts with the root: c:\windows is absolute, while c:temp and \temp are not.

Examples
use std::path::Path;

assert!(!Path::new("foo.txt").is_absolute());

Returns true if the Path is relative, i.e., not absolute.

See is_absolute’s documentation for more details.

Examples
use std::path::Path;

assert!(Path::new("foo.txt").is_relative());

Returns true if the Path has a root.

  • On Unix, a path has a root if it begins with /.

  • On Windows, a path has a root if it:

    • has no prefix and begins with a separator, e.g., \windows
    • has a prefix followed by a separator, e.g., c:\windows but not c:windows
    • has any non-disk prefix, e.g., \\server\share
Examples
use std::path::Path;

assert!(Path::new("/etc/passwd").has_root());

Returns the Path without its final component, if there is one.

This means it returns Some("") for relative paths with one component.

Returns None if the path terminates in a root or prefix, or if it’s the empty string.

Examples
use std::path::Path;

let path = Path::new("/foo/bar");
let parent = path.parent().unwrap();
assert_eq!(parent, Path::new("/foo"));

let grand_parent = parent.parent().unwrap();
assert_eq!(grand_parent, Path::new("/"));
assert_eq!(grand_parent.parent(), None);

let relative_path = Path::new("foo/bar");
let parent = relative_path.parent();
assert_eq!(parent, Some(Path::new("foo")));
let grand_parent = parent.and_then(Path::parent);
assert_eq!(grand_parent, Some(Path::new("")));
let great_grand_parent = grand_parent.and_then(Path::parent);
assert_eq!(great_grand_parent, None);

Produces an iterator over Path and its ancestors.

The iterator will yield the Path that is returned if the parent method is used zero or more times. That means, the iterator will yield &self, &self.parent().unwrap(), &self.parent().unwrap().parent().unwrap() and so on. If the parent method returns None, the iterator will do likewise. The iterator will always yield at least one value, namely &self.

Examples
use std::path::Path;

let mut ancestors = Path::new("/foo/bar").ancestors();
assert_eq!(ancestors.next(), Some(Path::new("/foo/bar")));
assert_eq!(ancestors.next(), Some(Path::new("/foo")));
assert_eq!(ancestors.next(), Some(Path::new("/")));
assert_eq!(ancestors.next(), None);

let mut ancestors = Path::new("../foo/bar").ancestors();
assert_eq!(ancestors.next(), Some(Path::new("../foo/bar")));
assert_eq!(ancestors.next(), Some(Path::new("../foo")));
assert_eq!(ancestors.next(), Some(Path::new("..")));
assert_eq!(ancestors.next(), Some(Path::new("")));
assert_eq!(ancestors.next(), None);

Returns the final component of the Path, if there is one.

If the path is a normal file, this is the file name. If it’s the path of a directory, this is the directory name.

Returns None if the path terminates in ...

Examples
use std::path::Path;
use std::ffi::OsStr;

assert_eq!(Some(OsStr::new("bin")), Path::new("/usr/bin/").file_name());
assert_eq!(Some(OsStr::new("foo.txt")), Path::new("tmp/foo.txt").file_name());
assert_eq!(Some(OsStr::new("foo.txt")), Path::new("foo.txt/.").file_name());
assert_eq!(Some(OsStr::new("foo.txt")), Path::new("foo.txt/.//").file_name());
assert_eq!(None, Path::new("foo.txt/..").file_name());
assert_eq!(None, Path::new("/").file_name());

Returns a path that, when joined onto base, yields self.

Errors

If base is not a prefix of self (i.e., starts_with returns false), returns Err.

Examples
use std::path::{Path, PathBuf};

let path = Path::new("/test/haha/foo.txt");

assert_eq!(path.strip_prefix("/"), Ok(Path::new("test/haha/foo.txt")));
assert_eq!(path.strip_prefix("/test"), Ok(Path::new("haha/foo.txt")));
assert_eq!(path.strip_prefix("/test/"), Ok(Path::new("haha/foo.txt")));
assert_eq!(path.strip_prefix("/test/haha/foo.txt"), Ok(Path::new("")));
assert_eq!(path.strip_prefix("/test/haha/foo.txt/"), Ok(Path::new("")));

assert!(path.strip_prefix("test").is_err());
assert!(path.strip_prefix("/haha").is_err());

let prefix = PathBuf::from("/test/");
assert_eq!(path.strip_prefix(prefix), Ok(Path::new("haha/foo.txt")));

Determines whether base is a prefix of self.

Only considers whole path components to match.

Examples
use std::path::Path;

let path = Path::new("/etc/passwd");

assert!(path.starts_with("/etc"));
assert!(path.starts_with("/etc/"));
assert!(path.starts_with("/etc/passwd"));
assert!(path.starts_with("/etc/passwd/")); // extra slash is okay
assert!(path.starts_with("/etc/passwd///")); // multiple extra slashes are okay

assert!(!path.starts_with("/e"));
assert!(!path.starts_with("/etc/passwd.txt"));

assert!(!Path::new("/etc/foo.rs").starts_with("/etc/foo"));

Determines whether child is a suffix of self.

Only considers whole path components to match.

Examples
use std::path::Path;

let path = Path::new("/etc/resolv.conf");

assert!(path.ends_with("resolv.conf"));
assert!(path.ends_with("etc/resolv.conf"));
assert!(path.ends_with("/etc/resolv.conf"));

assert!(!path.ends_with("/resolv.conf"));
assert!(!path.ends_with("conf")); // use .extension() instead

Extracts the stem (non-extension) portion of self.file_name.

The stem is:

  • None, if there is no file name;
  • The entire file name if there is no embedded .;
  • The entire file name if the file name begins with . and has no other .s within;
  • Otherwise, the portion of the file name before the final .
Examples
use std::path::Path;

assert_eq!("foo", Path::new("foo.rs").file_stem().unwrap());
assert_eq!("foo.tar", Path::new("foo.tar.gz").file_stem().unwrap());
See Also

This method is similar to Path::file_prefix, which extracts the portion of the file name before the first .

🔬This is a nightly-only experimental API. (path_file_prefix)

Extracts the prefix of self.file_name.

The prefix is:

  • None, if there is no file name;
  • The entire file name if there is no embedded .;
  • The portion of the file name before the first non-beginning .;
  • The entire file name if the file name begins with . and has no other .s within;
  • The portion of the file name before the second . if the file name begins with .
Examples
use std::path::Path;

assert_eq!("foo", Path::new("foo.rs").file_prefix().unwrap());
assert_eq!("foo", Path::new("foo.tar.gz").file_prefix().unwrap());
See Also

This method is similar to Path::file_stem, which extracts the portion of the file name before the last .

Extracts the extension (without the leading dot) of self.file_name, if possible.

The extension is:

  • None, if there is no file name;
  • None, if there is no embedded .;
  • None, if the file name begins with . and has no other .s within;
  • Otherwise, the portion of the file name after the final .
Examples
use std::path::Path;

assert_eq!("rs", Path::new("foo.rs").extension().unwrap());
assert_eq!("gz", Path::new("foo.tar.gz").extension().unwrap());

Creates an owned PathBuf with path adjoined to self.

See PathBuf::push for more details on what it means to adjoin a path.

Examples
use std::path::{Path, PathBuf};

assert_eq!(Path::new("/etc").join("passwd"), PathBuf::from("/etc/passwd"));

Creates an owned PathBuf like self but with the given file name.

See PathBuf::set_file_name for more details.

Examples
use std::path::{Path, PathBuf};

let path = Path::new("/tmp/foo.txt");
assert_eq!(path.with_file_name("bar.txt"), PathBuf::from("/tmp/bar.txt"));

let path = Path::new("/tmp");
assert_eq!(path.with_file_name("var"), PathBuf::from("/var"));

Creates an owned PathBuf like self but with the given extension.

See PathBuf::set_extension for more details.

Examples
use std::path::{Path, PathBuf};

let path = Path::new("foo.rs");
assert_eq!(path.with_extension("txt"), PathBuf::from("foo.txt"));

let path = Path::new("foo.tar.gz");
assert_eq!(path.with_extension(""), PathBuf::from("foo.tar"));
assert_eq!(path.with_extension("xz"), PathBuf::from("foo.tar.xz"));
assert_eq!(path.with_extension("").with_extension("txt"), PathBuf::from("foo.txt"));

Produces an iterator over the Components of the path.

When parsing the path, there is a small amount of normalization:

  • Repeated separators are ignored, so a/b and a//b both have a and b as components.

  • Occurrences of . are normalized away, except if they are at the beginning of the path. For example, a/./b, a/b/, a/b/. and a/b all have a and b as components, but ./a/b starts with an additional CurDir component.

  • A trailing slash is normalized away, /a/b and /a/b/ are equivalent.

Note that no other normalization takes place; in particular, a/c and a/b/../c are distinct, to account for the possibility that b is a symbolic link (so its parent isn’t a).

Examples
use std::path::{Path, Component};
use std::ffi::OsStr;

let mut components = Path::new("/tmp/foo.txt").components();

assert_eq!(components.next(), Some(Component::RootDir));
assert_eq!(components.next(), Some(Component::Normal(OsStr::new("tmp"))));
assert_eq!(components.next(), Some(Component::Normal(OsStr::new("foo.txt"))));
assert_eq!(components.next(), None)

Produces an iterator over the path’s components viewed as OsStr slices.

For more information about the particulars of how the path is separated into components, see components.

Examples
use std::path::{self, Path};
use std::ffi::OsStr;

let mut it = Path::new("/tmp/foo.txt").iter();
assert_eq!(it.next(), Some(OsStr::new(&path::MAIN_SEPARATOR.to_string())));
assert_eq!(it.next(), Some(OsStr::new("tmp")));
assert_eq!(it.next(), Some(OsStr::new("foo.txt")));
assert_eq!(it.next(), None)

Returns an object that implements Display for safely printing paths that may contain non-Unicode data. This may perform lossy conversion, depending on the platform. If you would like an implementation which escapes the path please use Debug instead.

Examples
use std::path::Path;

let path = Path::new("/tmp/foo.rs");

println!("{}", path.display());

Queries the file system to get information about a file, directory, etc.

This function will traverse symbolic links to query information about the destination file.

This is an alias to fs::metadata.

Examples
use std::path::Path;

let path = Path::new("/Minas/tirith");
let metadata = path.metadata().expect("metadata call failed");
println!("{:?}", metadata.file_type());

Queries the metadata about a file without following symlinks.

This is an alias to fs::symlink_metadata.

Examples
use std::path::Path;

let path = Path::new("/Minas/tirith");
let metadata = path.symlink_metadata().expect("symlink_metadata call failed");
println!("{:?}", metadata.file_type());

Returns the canonical, absolute form of the path with all intermediate components normalized and symbolic links resolved.

This is an alias to fs::canonicalize.

Examples
use std::path::{Path, PathBuf};

let path = Path::new("/foo/test/../test/bar.rs");
assert_eq!(path.canonicalize().unwrap(), PathBuf::from("/foo/test/bar.rs"));

Reads a symbolic link, returning the file that the link points to.

This is an alias to fs::read_link.

Examples
use std::path::Path;

let path = Path::new("/laputa/sky_castle.rs");
let path_link = path.read_link().expect("read_link call failed");

Returns an iterator over the entries within a directory.

The iterator will yield instances of io::Result<fs::DirEntry>. New errors may be encountered after an iterator is initially constructed.

This is an alias to fs::read_dir.

Examples
use std::path::Path;

let path = Path::new("/laputa");
for entry in path.read_dir().expect("read_dir call failed") {
    if let Ok(entry) = entry {
        println!("{:?}", entry.path());
    }
}

Returns true if the path points at an existing entity.

Warning: this method may be error-prone, consider using try_exists() instead! It also has a risk of introducing time-of-check to time-of-use (TOCTOU) bugs.

This function will traverse symbolic links to query information about the destination file.

If you cannot access the metadata of the file, e.g. because of a permission error or broken symbolic links, this will return false.

Examples
use std::path::Path;
assert!(!Path::new("does_not_exist.txt").exists());
See Also

This is a convenience function that coerces errors to false. If you want to check errors, call Path::try_exists.

Returns Ok(true) if the path points at an existing entity.

This function will traverse symbolic links to query information about the destination file. In case of broken symbolic links this will return Ok(false).

As opposed to the exists() method, this one doesn’t silently ignore errors unrelated to the path not existing. (E.g. it will return Err(_) in case of permission denied on some of the parent directories.)

Note that while this avoids some pitfalls of the exists() method, it still can not prevent time-of-check to time-of-use (TOCTOU) bugs. You should only use it in scenarios where those bugs are not an issue.

Examples
use std::path::Path;
assert!(!Path::new("does_not_exist.txt").try_exists().expect("Can't check existence of file does_not_exist.txt"));
assert!(Path::new("/root/secret_file.txt").try_exists().is_err());

Returns true if the path exists on disk and is pointing at a regular file.

This function will traverse symbolic links to query information about the destination file.

If you cannot access the metadata of the file, e.g. because of a permission error or broken symbolic links, this will return false.

Examples
use std::path::Path;
assert_eq!(Path::new("./is_a_directory/").is_file(), false);
assert_eq!(Path::new("a_file.txt").is_file(), true);
See Also

This is a convenience function that coerces errors to false. If you want to check errors, call fs::metadata and handle its Result. Then call fs::Metadata::is_file if it was Ok.

When the goal is simply to read from (or write to) the source, the most reliable way to test the source can be read (or written to) is to open it. Only using is_file can break workflows like diff <( prog_a ) on a Unix-like system for example. See fs::File::open or fs::OpenOptions::open for more information.

Returns true if the path exists on disk and is pointing at a directory.

This function will traverse symbolic links to query information about the destination file.

If you cannot access the metadata of the file, e.g. because of a permission error or broken symbolic links, this will return false.

Examples
use std::path::Path;
assert_eq!(Path::new("./is_a_directory/").is_dir(), true);
assert_eq!(Path::new("a_file.txt").is_dir(), false);
See Also

This is a convenience function that coerces errors to false. If you want to check errors, call fs::metadata and handle its Result. Then call fs::Metadata::is_dir if it was Ok.

Returns true if the path exists on disk and is pointing at a symbolic link.

This function will not traverse symbolic links. In case of a broken symbolic link this will also return true.

If you cannot access the directory containing the file, e.g., because of a permission error, this will return false.

Examples
use std::path::Path;
use std::os::unix::fs::symlink;

let link_path = Path::new("link");
symlink("/origin_does_not_exist/", link_path).unwrap();
assert_eq!(link_path.is_symlink(), true);
assert_eq!(link_path.exists(), false);
See Also

This is a convenience function that coerces errors to false. If you want to check errors, call fs::symlink_metadata and handle its Result. Then call fs::Metadata::is_symlink if it was Ok.

Trait Implementations§

Converts this type into a shared reference of the (usually inferred) input type.
Formats the value using the given formatter. Read more
The resulting type after dereferencing.
Dereferences the value.
Create an empty file at ChildPath. Read more
Write a binary file at ChildPath. Read more
Write (copy) a file to ChildPath. Read more
Write a text file at ChildPath. Read more
Assert the state of files within TempDir. Read more
Create a symlink to the target Read more

Auto Trait Implementations§

Blanket Implementations§

Gets the TypeId of self. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.