1 // Copyright 2020, The Android Open Source Project
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 //     http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 
15 //! Implements TempDir which aids in creating an cleaning up temporary directories for testing.
16 
17 use std::fs::{create_dir, remove_dir_all};
18 use std::io::ErrorKind;
19 use std::path::{Path, PathBuf};
20 use std::{env::temp_dir, ops::Deref};
21 
22 /// Represents the lifecycle of a temporary directory for testing.
23 #[derive(Debug)]
24 pub struct TempDir {
25     path: std::path::PathBuf,
26     do_drop: bool,
27 }
28 
29 impl TempDir {
30     /// Creates a temporary directory with a name of the form <prefix>_NNNNN where NNNNN is a zero
31     /// padded random number with 5 figures. The prefix must not contain file system separators.
32     /// The location of the directory cannot be chosen.
33     /// The directory with all of its content is removed from the file system when the resulting
34     /// object gets dropped.
new(prefix: &str) -> std::io::Result<Self>35     pub fn new(prefix: &str) -> std::io::Result<Self> {
36         let tmp = loop {
37             let mut tmp = temp_dir();
38             let number: u16 = rand::random();
39             tmp.push(format!("{}_{:05}", prefix, number));
40             match create_dir(&tmp) {
41                 Err(e) => match e.kind() {
42                     ErrorKind::AlreadyExists => continue,
43                     _ => return Err(e),
44                 },
45                 Ok(()) => break tmp,
46             }
47         };
48         Ok(Self { path: tmp, do_drop: true })
49     }
50 
51     /// Returns the absolute path of the temporary directory.
path(&self) -> &Path52     pub fn path(&self) -> &Path {
53         &self.path
54     }
55 
56     /// Returns a path builder for convenient extension of the path.
57     ///
58     /// ## Example:
59     ///
60     /// ```
61     /// let tdir = TempDir::new("my_test")?;
62     /// let temp_foo_bar = tdir.build().push("foo").push("bar");
63     /// ```
64     /// `temp_foo_bar` derefs to a Path that represents "<tdir.path()>/foo/bar"
build(&self) -> PathBuilder65     pub fn build(&self) -> PathBuilder {
66         PathBuilder(self.path.clone())
67     }
68 
69     /// When a test is failing you can set this to false in order to inspect
70     /// the directory structure after the test failed.
71     #[allow(dead_code)]
do_not_drop(&mut self)72     pub fn do_not_drop(&mut self) {
73         println!("Disabled automatic cleanup for: {:?}", self.path);
74         log::info!("Disabled automatic cleanup for: {:?}", self.path);
75         self.do_drop = false;
76     }
77 }
78 
79 impl Drop for TempDir {
drop(&mut self)80     fn drop(&mut self) {
81         if self.do_drop {
82             remove_dir_all(&self.path).expect("Cannot delete temporary dir.");
83         }
84     }
85 }
86 
87 /// Allows for convenient building of paths from a TempDir. See TempDir.build() for more details.
88 pub struct PathBuilder(PathBuf);
89 
90 impl PathBuilder {
91     /// Adds another segment to the end of the path. Consumes, modifies and returns self.
push(mut self, segment: &str) -> Self92     pub fn push(mut self, segment: &str) -> Self {
93         self.0.push(segment);
94         self
95     }
96 }
97 
98 impl Deref for PathBuilder {
99     type Target = Path;
100 
deref(&self) -> &Self::Target101     fn deref(&self) -> &Self::Target {
102         &self.0
103     }
104 }
105