feat(tmpdir): Augment tempdir::TempDir

This is an experiment in what kind of tempdir operations a holistic CLI
testing framework might provide, following on the previous experiments
with extension traits. The exact structure in this crate or across
crates is TBD.

This crate extends `TempDir` with the following
- In TempDir or a child path, run a command.
- On child path, touch a file.
- On child path, write a binary blob or str to file.
- Copy to a TempDir or a child path some files.

Some other potential operations include
- `write_yml(serde)`
- `write_json(serde)`
- `write_toml(serde)`

In contrast, `cli_test_dir` can:
- Run a single pre-defined program within the tempdir
- Write binary files to tempdir
- Offer a absolute path to a child file within the crate source (so its
  safe to pass to the program running in the tempdir).

Cargo.toml

@@ -15,13 +15,19 @@ build = "build.rs"
 [[bin]]
 name = "assert_fixture"
 
+[features]
+default = ["tempdir"]
+tempdir = ["tempfile", "globwalk"]
+
 [dependencies]
 colored = "1.5"
 difference = "2.0"
 failure = "0.1"
 failure_derive = "0.1"
 serde_json = "1.0"
 environment = "0.1"
+tempfile = { version="3.0", optional=true }
+globwalk = { version="0.1", optional=true }
 
 [build-dependencies]
 skeptic = "0.13"

src/lib.rs

@@ -124,7 +124,9 @@ extern crate environment;
 extern crate failure;
 #[macro_use]
 extern crate failure_derive;
+extern crate globwalk;
 extern crate serde_json;
+extern crate tempfile;
 
 mod errors;
 pub use errors::AssertionError;
@@ -139,6 +141,9 @@ mod output;
 
 /// `std::process::Command` extensions.
 pub mod cmd;
+/// `tempfile::TempDir` extensions.
+#[cfg(feature = "tempdir")]
+pub mod temp;
 
 pub use assert::Assert;
 pub use assert::OutputAssertionBuilder;

src/temp.rs

@@ -0,0 +1,269 @@
+use std::ffi;
+use std::fs;
+use std::io;
+use std::io::Write;
+use std::path;
+use std::process;
+
+use globwalk;
+use tempfile;
+use failure;
+
+// Quick and dirty for doc tests; not meant for long term use.
+pub use tempfile::TempDir;
+
+/// Extend `TempDir` to perform operations on relative paths within the temp directory via
+/// `ChildPath`.
+pub trait TempDirChildExt {
+    /// Create a path within the temp directory.
+    ///
+    /// # Examples
+    ///
+    /// ```rust,ignore
+    /// extern crate assert_cli;
+    /// use assert_cli::temp::*;
+    ///
+    /// let temp = TempDir::new("TempDirChildExt_demo").unwrap();
+    /// println!("{:?}", temp.path());
+    /// println!("{:?}", temp.child("foo/bar.txt").path());
+    /// temp.close().unwrap();
+    /// ```
+    fn child<P>(&self, path: P) -> ChildPath
+    where
+        P: AsRef<path::Path>;
+}
+
+impl TempDirChildExt for tempfile::TempDir {
+    fn child<P>(&self, path: P) -> ChildPath
+    where
+        P: AsRef<path::Path>,
+    {
+        ChildPath::new(self.path().join(path.as_ref()))
+    }
+}
+
+/// A path within a TempDir
+pub struct ChildPath {
+    path: path::PathBuf,
+}
+
+impl ChildPath {
+    /// Wrap a path for use with special built extension traits.
+    ///
+    /// See trait implementations or `TempDirChildExt` for more details.
+    pub fn new<P>(path: P) -> Self
+    where
+        P: Into<path::PathBuf>,
+    {
+        Self { path: path.into() }
+    }
+
+    /// Access the path.
+    pub fn path(&self) -> &path::Path {
+        &self.path
+    }
+}
+
+/// Extend `TempDir` to run commands in it.
+pub trait TempDirCommandExt {
+    /// Constructs a new Command for launching the program at path program, with the following
+    /// default configuration:
+    ///
+    /// - The current working directory is the temp dir
+    /// - No arguments to the program
+    /// - Inherit the current process's environment
+    /// - Inherit the current process's working directory
+    /// - Inherit stdin/stdout/stderr for spawn or status, but create pipes for output
+    /// - Builder methods are provided to change these defaults and otherwise configure the process.
+    ///
+    /// If program is not an absolute path, the PATH will be searched in an OS-defined way.
+    ///
+    /// The search path to be used may be controlled by setting the PATH environment variable on
+    /// the Command, but this has some implementation limitations on Windows (see
+    /// https://github.com/rust-lang/rust/issues/37519).
+    ///
+    /// # Examples
+    ///
+    /// ```rust,ignore
+    /// extern crate assert_cli;
+    /// use assert_cli::temp::*;
+    ///
+    /// let temp = TempDir::new("TempDirChildExt_demo").unwrap();
+    /// temp.command("pwd").output().unwrap();
+    /// temp.close().unwrap();
+    /// ```
+    fn command<S>(&self, program: S) -> process::Command
+    where
+        S: AsRef<ffi::OsStr>;
+}
+
+impl TempDirCommandExt for tempfile::TempDir {
+    fn command<S>(&self, program: S) -> process::Command
+    where
+        S: AsRef<ffi::OsStr>,
+    {
+        let mut cmd = process::Command::new(program);
+        cmd.current_dir(self.path());
+        cmd
+    }
+}
+
+impl TempDirCommandExt for ChildPath {
+    fn command<S>(&self, program: S) -> process::Command
+    where
+        S: AsRef<ffi::OsStr>,
+    {
+        let mut cmd = process::Command::new(program);
+        cmd.current_dir(self.path());
+        cmd
+    }
+}
+
+/// Extend `ChildPath` to create empty files.
+pub trait ChildPathTouchExt {
+    /// Create an empty file at `ChildPath`.
+    ///
+    /// # Examples
+    ///
+    /// ```rust,ignore
+    /// extern crate assert_cli;
+    /// use assert_cli::temp::*;
+    ///
+    /// let temp = TempDir::new("TempDirChildExt_demo").unwrap();
+    /// temp.child("foo.txt").touch().unwrap();
+    /// temp.close().unwrap();
+    /// ```
+    fn touch(&self) -> io::Result<()>;
+}
+
+impl ChildPathTouchExt for ChildPath {
+    fn touch(&self) -> io::Result<()> {
+        touch(self.path())
+    }
+}
+
+/// Extend `ChildPath` to write binary files.
+pub trait ChildPathWriteBinExt {
+    /// Write a binary file at `ChildPath`.
+    ///
+    /// # Examples
+    ///
+    /// ```rust,ignore
+    /// extern crate assert_cli;
+    /// use assert_cli::temp::*;
+    ///
+    /// let temp = TempDir::new("TempDirChildExt_demo").unwrap();
+    /// temp.child("foo.txt").write_binary(b"To be or not to be...").unwrap();
+    /// temp.close().unwrap();
+    /// ```
+    fn write_binary(&self, data: &[u8]) -> io::Result<()>;
+}
+
+impl ChildPathWriteBinExt for ChildPath {
+    fn write_binary(&self, data: &[u8]) -> io::Result<()> {
+        write_binary(self.path(), data)
+    }
+}
+
+/// Extend `ChildPath` to write text files.
+pub trait ChildPathWriteStrExt {
+    /// Write a text file at `ChildPath`.
+    ///
+    /// # Examples
+    ///
+    /// ```rust,ignore
+    /// extern crate assert_cli;
+    /// use assert_cli::temp::*;
+    ///
+    /// let temp = TempDir::new("TempDirChildExt_demo").unwrap();
+    /// temp.child("foo.txt").write_str("To be or not to be...").unwrap();
+    /// temp.close().unwrap();
+    /// ```
+    fn write_str(&self, data: &str) -> io::Result<()>;
+}
+
+impl ChildPathWriteStrExt for ChildPath {
+    fn write_str(&self, data: &str) -> io::Result<()> {
+        write_str(self.path(), data)
+    }
+}
+
+/// Extend `TempDir` to copy files into it.
+pub trait TempDirCopyExt {
+    /// Copy files and directories into the current path from the `source` according to the glob
+    /// `patterns`.
+    ///
+    /// # Examples
+    ///
+    /// ```rust,ignore
+    /// extern crate assert_cli;
+    /// use assert_cli::temp::*;
+    ///
+    /// let temp = TempDir::new("TempDirChildExt_demo").unwrap();
+    /// temp.copy_from(".", &["*.rs"]).unwrap();
+    /// temp.close().unwrap();
+    /// ```
+    fn copy_from<P, S>(&self, source: P, patterns: &[S]) -> Result<(), failure::Error>
+    where
+        P: AsRef<path::Path>,
+        S: AsRef<str>;
+}
+
+impl TempDirCopyExt for tempfile::TempDir {
+    fn copy_from<P, S>(&self, source: P, patterns: &[S]) -> Result<(), failure::Error>
+    where
+        P: AsRef<path::Path>,
+        S: AsRef<str>,
+    {
+        copy_from(self.path(), source.as_ref(), patterns)
+    }
+}
+
+impl TempDirCopyExt for ChildPath {
+    fn copy_from<P, S>(&self, source: P, patterns: &[S]) -> Result<(), failure::Error>
+    where
+        P: AsRef<path::Path>,
+        S: AsRef<str>,
+    {
+        copy_from(self.path(), source.as_ref(), patterns)
+    }
+}
+
+fn touch(path: &path::Path) -> io::Result<()> {
+    fs::File::create(path)?;
+    Ok(())
+}
+
+fn write_binary(path: &path::Path, data: &[u8]) -> io::Result<()> {
+    let mut file = fs::File::create(path)?;
+    file.write_all(data)?;
+    Ok(())
+}
+
+fn write_str(path: &path::Path, data: &str) -> io::Result<()> {
+    write_binary(path, data.as_bytes())
+}
+
+fn copy_from<S>(
+    target: &path::Path,
+    source: &path::Path,
+    patterns: &[S],
+) -> Result<(), failure::Error>
+where
+    S: AsRef<str>,
+{
+    for entry in globwalk::GlobWalker::from_patterns(patterns, source)?.follow_links(true) {
+        let entry = entry?;
+        let rel = entry
+            .path()
+            .strip_prefix(source)
+            .expect("entries to be under `source`");
+        let target_path = target.join(rel);
+        if entry.file_type().is_dir() {
+            fs::create_dir_all(target_path)?;
+        } else if entry.file_type().is_file() {
+            fs::copy(entry.path(), target)?;
+        }
+    }
+    Ok(())
+}