Avoid dependency on Rust nightly for capturing test output

Instead of using unstable API available only on Rust nightly, this uses
the gag crate to capture stdout and stderr of the test scenarios. This
has one downside though, that crate currently works only on Unix-like
systems. But it is strictly more general as it redirects file
descriptors instead of just change the Rust-specific stdout and stderr
locked readers and writers.

Cargo.toml

@@ -9,7 +9,6 @@ repository = "https://github.com/bbqsrc/cucumber-rust"
 documentation = "https://docs.rs/cucumber_rust"
 homepage = "https://github.com/bbqsrc/cucumber-rust"
 edition = "2018"
-build = "build.rs"
 
 [badges]
 travis-ci = { repository = "bbqsrc/cucumber-rust" }
@@ -26,9 +25,5 @@ pathdiff = "^0.1.0"
 textwrap = { version = "0.11", features = ["term_size"] }
 clap = "^2.32.0"
 globwalk = "0.7"
-
-[build-dependencies]
-rustc_version = "0.2"
-
-[features]
-nightly = []
+gag = "0.1"
+tempfile = "3.0"

src/cli.rs

@@ -59,7 +59,7 @@ pub fn make_app() -> Result<CliOptions, CliError> {
     let feature = matches.value_of("feature").map(|v| v.to_string());
     let tag = matches.value_of("tag").map(|v| v.to_string());
 
-    let suppress_output = cfg!(feature = "nightly") && !matches.is_present("nocapture");
+    let suppress_output = !matches.is_present("nocapture");
 
     Ok(CliOptions {
         feature,

src/lib.rs

@@ -6,8 +6,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![cfg_attr(feature = "nightly", feature(set_stdio))]
-
 pub extern crate gherkin_rust as gherkin;
 pub extern crate globwalk;
 pub extern crate regex;

src/panic_trap.rs

@@ -1,8 +1,11 @@
-use std::io::{self, Write};
+use std::io::{Read, Seek, SeekFrom};
 use std::ops::Deref;
 use std::panic;
 use std::sync::{Arc, Mutex};
 
+use gag::Redirect;
+use tempfile::tempfile;
+
 #[derive(Clone)]
 pub struct PanicDetails {
     pub payload: String,
@@ -29,19 +32,6 @@ impl PanicDetails {
     }
 }
 
-#[derive(Default)]
-struct Sink(Arc<Mutex<Vec<u8>>>);
-
-impl Write for Sink {
-    fn write(&mut self, data: &[u8]) -> io::Result<usize> {
-        Write::write(&mut *self.0.lock().unwrap(), data)
-    }
-
-    fn flush(&mut self) -> io::Result<()> {
-        self.0.lock().unwrap().flush()
-    }
-}
-
 pub struct PanicTrap<T> {
     pub stdout: Vec<u8>,
     pub result: Result<T, PanicDetails>,
@@ -56,35 +46,28 @@ impl<T> PanicTrap<T> {
         }
     }
 
-    #[cfg(feature = "nightly")]
     fn run_quietly<F: FnOnce() -> T>(f: F) -> PanicTrap<T> {
-        let stdout_sink = Arc::new(Mutex::new(vec![]));
-        let stdout_sink_hook = stdout_sink.clone();
-        let old_io = (
-            io::set_print(Some(Box::new(Sink(stdout_sink.clone())))),
-            io::set_panic(Some(Box::new(Sink(stdout_sink)))),
-        );
-
-        let loud_panic_trap = PanicTrap::run_loudly(f);
-
-        io::set_print(old_io.0);
-        io::set_panic(old_io.1);
-
-        let stdout = stdout_sink_hook
-            .lock()
-            .expect("Stdout mutex poisoned")
-            .clone();
+        let mut tmp = tempfile().unwrap();
+
+        let loud_panic_trap = {
+            let _stdout =
+                Redirect::stdout(tmp.try_clone().unwrap()).expect("Failed to capture stdout");
+            let _stderr =
+                Redirect::stderr(tmp.try_clone().unwrap()).expect("Failed to capture stderr");
+
+            PanicTrap::run_loudly(f)
+        };
+
+        let mut stdout = Vec::new();
+        tmp.seek(SeekFrom::Start(0)).unwrap();
+        tmp.read_to_end(&mut stdout).unwrap();
+
         PanicTrap {
             stdout,
             result: loud_panic_trap.result,
         }
     }
 
-    #[cfg(not(feature = "nightly"))]
-    fn run_quietly<F: FnOnce() -> T>(_f: F) -> PanicTrap<T> {
-        panic!("PanicTrap cannot run quietly without the 'nightly' feature");
-    }
-
     fn run_loudly<F: FnOnce() -> T>(f: F) -> PanicTrap<T> {
         let last_panic = Arc::new(Mutex::new(None));