Add tests for TestDirExt

Some of these tests are ignored, because they trigger known TestDirExt
bugs. See #1140 for details.

zebra-test/tests/command.rs

@@ -0,0 +1,169 @@
+#![allow(clippy::try_err)]
+
+use std::{process::Command, time::Duration};
+
+use color_eyre::eyre::Result;
+use tempdir::TempDir;
+
+use zebra_test::{command::TestDirExt, prelude::Stdio};
+
+/// Returns true if `cmd` with `args` runs successfully.
+///
+/// On failure, prints an error message to stderr.
+/// (This message is captured by the test runner, use `cargo test -- --nocapture` to see it.)
+///
+/// The command's stdout and stderr are ignored.
+fn is_command_available(cmd: &str, args: &[&str]) -> bool {
+    let status = Command::new(cmd)
+        .args(args)
+        .stdout(Stdio::null())
+        .stderr(Stdio::null())
+        .status();
+
+    match status {
+        Err(e) => {
+            eprintln!(
+                "Skipping test because '{} {:?}' returned error {:?}",
+                cmd, args, e
+            );
+            false
+        }
+        Ok(status) if !status.success() => {
+            eprintln!(
+                "Skipping test because '{} {:?}' returned status {:?}",
+                cmd, args, status
+            );
+            false
+        }
+        _ => true,
+    }
+}
+
+/// Test if a process that keeps on producing lines of output is killed after the timeout.
+#[test]
+fn kill_on_timeout_output_continuous_lines() -> Result<()> {
+    zebra_test::init();
+
+    // Ideally, we'd want to use the 'yes' command here, but BSD yes treats
+    // every string as an argument to repeat - so we can't test if it is
+    // present on the system.
+    const TEST_CMD: &str = "hexdump";
+    // Skip the test if the test system does not have the command
+    if !is_command_available(TEST_CMD, &["/dev/null"]) {
+        return Ok(());
+    }
+
+    // Without '-v', hexdump hides duplicate lines. But we want duplicate lines
+    // in this test.
+    let mut child = TempDir::new("zebra_test")?
+        .spawn_child_with_command(TEST_CMD, &["-v", "/dev/zero"])?
+        .with_timeout(Duration::from_secs(2));
+
+    // We need to use expect_stdout, because wait_with_output ignores timeouts.
+    // We use a non-matching regex, to trigger the timeout.
+    assert!(child.expect_stdout("this regex should not match").is_err());
+
+    Ok(())
+}
+
+/// Test if the tests pass for a process that produces a single line of output,
+/// then exits before the timeout.
+//
+// TODO: create a similar test that pauses after output
+#[test]
+fn finish_before_timeout_output_single_line() -> Result<()> {
+    zebra_test::init();
+
+    const TEST_CMD: &str = "echo";
+    // Skip the test if the test system does not have the command
+    if !is_command_available(TEST_CMD, &[]) {
+        return Ok(());
+    }
+
+    let mut child = TempDir::new("zebra_test")?
+        .spawn_child_with_command(TEST_CMD, &["zebra_test_output"])?
+        .with_timeout(Duration::from_secs(2));
+
+    // We need to use expect_stdout, because wait_with_output ignores timeouts.
+    // We use a non-matching regex, to trigger the timeout.
+    assert!(child.expect_stdout("this regex should not match").is_err());
+
+    Ok(())
+}
+
+/// Test if a process that keeps on producing output, but doesn't produce any newlines,
+/// is killed after the timeout.
+///
+/// This test fails due to bugs in TestDirExt, see #1140 for details.
+#[test]
+#[ignore]
+fn kill_on_timeout_continuous_output_no_newlines() -> Result<()> {
+    zebra_test::init();
+
+    const TEST_CMD: &str = "cat";
+    // Skip the test if the test system does not have the command
+    if !is_command_available(TEST_CMD, &["/dev/null"]) {
+        return Ok(());
+    }
+
+    let mut child = TempDir::new("zebra_test")?
+        .spawn_child_with_command(TEST_CMD, &["/dev/zero"])?
+        .with_timeout(Duration::from_secs(2));
+
+    // We need to use expect_stdout, because wait_with_output ignores timeouts.
+    // We use a non-matching regex, to trigger the timeout.
+    assert!(child.expect_stdout("this regex should not match").is_err());
+
+    Ok(())
+}
+
+/// Test if tests pass for a process that produces a small amount of output,
+/// with no newlines, then exits before the timeout.
+//
+// TODO: create a similar test that pauses after output
+#[test]
+fn finish_before_timeout_short_output_no_newlines() -> Result<()> {
+    zebra_test::init();
+
+    const TEST_CMD: &str = "printf";
+    // Skip the test if the test system does not have the command
+    // The empty argument is required, because printf expects at least one argument.
+    if !is_command_available(TEST_CMD, &[""]) {
+        return Ok(());
+    }
+
+    let mut child = TempDir::new("zebra_test")?
+        .spawn_child_with_command(TEST_CMD, &["zebra_test_output"])?
+        .with_timeout(Duration::from_secs(2));
+
+    // We need to use expect_stdout, because wait_with_output ignores timeouts.
+    // We use a non-matching regex, to trigger the timeout.
+    assert!(child.expect_stdout("this regex should not match").is_err());
+
+    Ok(())
+}
+
+/// Test if the timeout works for a process that produces no output.
+///
+/// This test fails due to bugs in TestDirExt, see #1140 for details.
+#[test]
+#[ignore]
+fn kill_on_timeout_no_output() -> Result<()> {
+    zebra_test::init();
+
+    const TEST_CMD: &str = "sleep";
+    // Skip the test if the test system does not have the command
+    if !is_command_available(TEST_CMD, &["0"]) {
+        return Ok(());
+    }
+
+    let mut child = TempDir::new("zebra_test")?
+        .spawn_child_with_command(TEST_CMD, &["120"])?
+        .with_timeout(Duration::from_secs(2));
+
+    // We need to use expect_stdout, because wait_with_output ignores timeouts.
+    // We use a non-matching regex, to trigger the timeout.
+    assert!(child.expect_stdout("this regex should not match").is_err());
+
+    Ok(())
+}