Keystore 2.0: Move test utils to separate library.

Move TempDir test utils to separate library for easier reuse.

Test: keystore2_test
Change-Id: If1edfde39b66efa43f8a5ed32a500fad57291512

1 files changed, 104 insertions, 0 deletions

diff --git a/keystore2/test_utils/lib.rs b/keystore2/test_utils/lib.rs
new file mode 100644
index 00000000..627af20c
--- /dev/null
+++ b/keystore2/test_utils/lib.rs
@@ -0,0 +1,104 @@
+// Copyright 2020, The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Implements TempDir which aids in creating an cleaning up temporary directories for testing.
+
+use std::fs::{create_dir, remove_dir_all};
+use std::io::ErrorKind;
+use std::path::{Path, PathBuf};
+use std::{env::temp_dir, ops::Deref};
+
+/// Represents the lifecycle of a temporary directory for testing.
+#[derive(Debug)]
+pub struct TempDir {
+    path: std::path::PathBuf,
+    do_drop: bool,
+}
+
+impl TempDir {
+    /// Creates a temporary directory with a name of the form <prefix>_NNNNN where NNNNN is a zero
+    /// padded random number with 5 figures. The prefix must not contain file system separators.
+    /// The location of the directory cannot be chosen.
+    /// The directory with all of its content is removed from the file system when the resulting
+    /// object gets dropped.
+    pub fn new(prefix: &str) -> std::io::Result<Self> {
+        let tmp = loop {
+            let mut tmp = temp_dir();
+            let number: u16 = rand::random();
+            tmp.push(format!("{}_{:05}", prefix, number));
+            match create_dir(&tmp) {
+                Err(e) => match e.kind() {
+                    ErrorKind::AlreadyExists => continue,
+                    _ => return Err(e),
+                },
+                Ok(()) => break tmp,
+            }
+        };
+        Ok(Self { path: tmp, do_drop: true })
+    }
+
+    /// Returns the absolute path of the temporary directory.
+    pub fn path(&self) -> &Path {
+        &self.path
+    }
+
+    /// Returns a path builder for convenient extension of the path.
+    ///
+    /// ## Example:
+    ///
+    /// ```
+    /// let tdir = TempDir::new("my_test")?;
+    /// let temp_foo_bar = tdir.build().push("foo").push("bar");
+    /// ```
+    /// `temp_foo_bar` derefs to a Path that represents "<tdir.path()>/foo/bar"
+    pub fn build(&self) -> PathBuilder {
+        PathBuilder(self.path.clone())
+    }
+
+    /// When a test is failing you can set this to false in order to inspect
+    /// the directory structure after the test failed.
+    #[allow(dead_code)]
+    pub fn do_not_drop(&mut self) {
+        println!("Disabled automatic cleanup for: {:?}", self.path);
+        log::info!("Disabled automatic cleanup for: {:?}", self.path);
+        self.do_drop = false;
+    }
+}
+
+impl Drop for TempDir {
+    fn drop(&mut self) {
+        if self.do_drop {
+            remove_dir_all(&self.path).expect("Cannot delete temporary dir.");
+        }
+    }
+}
+
+/// Allows for convenient building of paths from a TempDir. See TempDir.build() for more details.
+pub struct PathBuilder(PathBuf);
+
+impl PathBuilder {
+    /// Adds another segment to the end of the path. Consumes, modifies and returns self.
+    pub fn push(mut self, segment: &str) -> Self {
+        self.0.push(segment);
+        self
+    }
+}
+
+impl Deref for PathBuilder {
+    type Target = Path;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}