Fix a timeout bug in zebra_test::command

And add tests for the command functionality.

Also document some remaining bugs (see ZcashFoundation#1140).

zebra-test/Cargo.toml

@@ -22,6 +22,7 @@ thiserror = "1.0.21"
 pretty_assertions = "0.6.1"
 owo-colors = "1.1.3"
 proptest = "0.10.1"
+tempdir = "0.3.7"
 
 [dev-dependencies]
 tokio = { version = "0.2", features = ["full"] }

zebra-test/src/command.rs

@@ -123,6 +123,7 @@ pub struct TestChild<T> {
 }
 
 impl<T> TestChild<T> {
+    /// Kill the child process.
     #[spandoc::spandoc]
     pub fn kill(&mut self) -> Result<()> {
         /// SPANDOC: Killing child process
@@ -131,6 +132,9 @@ impl<T> TestChild<T> {
         Ok(())
     }
 
+    /// Waits for the child process to exit, then returns its output.
+    ///
+    /// Ignores any configured timeouts.
     #[spandoc::spandoc]
     pub fn wait_with_output(self) -> Result<TestOutput<T>> {
         /// SPANDOC: waiting for command to exit
@@ -146,11 +150,18 @@ impl<T> TestChild<T> {
         })
     }
 
+    /// Set a timeout for `expect_stdout`.
+    ///
+    /// Does not apply to `wait_with_output`.
     pub fn with_timeout(mut self, timeout: Duration) -> Self {
         self.deadline = Some(Instant::now() + timeout);
         self
     }
 
+    /// Checks each line of the child's stdout against `regex`, and returns matching lines.
+    ///
+    /// Kills the child after the configured timeout has elapsed.
+    /// Note: the timeout is only checked after each line.
     #[instrument(skip(self))]
     pub fn expect_stdout(&mut self, regex: &str) -> Result<&mut Self> {
         if self.stdout.is_none() {
@@ -186,7 +197,10 @@ impl<T> TestChild<T> {
             }
         }
 
-        if self.past_deadline() && !self.is_running() {
+        if self.past_deadline() && self.is_running() {
+            // If the process exits between is_running and kill, we will see
+            // spurious errors here. If that happens, ignore "no such process"
+            // errors from kill.
             self.kill()?;
         }
 

zebrad/tests/acceptance.rs

@@ -44,21 +44,22 @@ fn testdir() -> Result<TempDir> {
 }
 
 /// Extension trait for methods on `tempdir::TempDir` for using it as a test
-/// directory.
-trait TestDirExt
+/// directory for `zebrad`.
+trait ZebradTestDirExt
 where
     Self: Borrow<TempDir> + Sized,
 {
-    /// Spawn the zebrad as a child process in this test directory, potentially
-    /// taking ownership of the tempdir for the duration of the child process.
+    /// Spawn `zebrad` with `args` as a child process in this test directory,
+    /// potentially taking ownership of the tempdir for the duration of the
+    /// child process.
     fn spawn_child(self, args: &[&str]) -> Result<TestChild<Self>>;
 
     /// Add the given config to the test directory and use it for all
     /// subsequently spawned processes.
     fn with_config(self, config: ZebradConfig) -> Result<Self>;
 }
 
-impl<T> TestDirExt for T
+impl<T> ZebradTestDirExt for T
 where
     Self: Borrow<TempDir> + Sized,
 {