Fix a race condition in some tests (#1821)

Some tests were modeled as "do a thing piped into another thing" but the
second command didn't actually take any input. That meant that writing
the stdout of the previous command into the next command might sometimes
fail if the second command finishes before the write finishes. This
commit fixes the various affected tests with the now-added ability to
run multiple separate commands in a single file. These failures were
detected by inserting a `sleep` before writing stdin and then fixing all
tests.

Closes #1820

Author: alexcrichton

tests/cli.rs

@@ -161,11 +161,13 @@ fn execute(cmd: &mut Command, stdin: Option<&[u8]>, should_fail: bool) -> Result
 
     let mut io = p.stdin.take().unwrap();
     if let Some(stdin) = stdin {
-        io.write_all(stdin)?;
+        io.write_all(stdin).context("failed to write to stdin")?;
     }
     drop(io);
 
-    let output = p.wait_with_output()?;
+    let output = p
+        .wait_with_output()
+        .context("failed to wait for process exit")?;
 
     let mut failure = None;
     match output.status.code() {

tests/cli/unbundle-print-module.wat

@@ -0,0 +1,12 @@
+;; RUN[gen]: component unbundle --threshold 0 % --module-dir %tmpdir
+;; RUN[read0]: print %tmpdir/unbundled-module0.wasm
+;; RUN[read1]: print %tmpdir/unbundled-module1.wasm
+
+(component
+  (core module $a
+    (import "a" "a" (func))
+  )
+  (core module $b
+    (import "b" "b" (func))
+  )
+)

tests/cli/unbundle-print-module.wat.gen.stdout

@@ -1,4 +1,5 @@
-// RUN: component wit % --out-dir %tmpdir | component wit %tmpdir
+// RUN[gen]: component wit % --out-dir %tmpdir
+// RUN[read]: component wit %tmpdir
 
 package foo:root;
 package a:b@0.2.0 {
@@ -14,4 +15,4 @@ package a:c {
     import a:b/foo@0.2.0;
     import a:b/foo;
   }
-}
+}

tests/cli/unbundle-print-module0.wat.stdout renamed to tests/cli/unbundle-print-module.wat.read0.stdout

@@ -0,0 +1,4 @@
+Writing: %tmpdir/deps/b.wit
+Writing: %tmpdir/deps/[email protected]
+Writing: %tmpdir/deps/c.wit
+Writing: %tmpdir/root.wit

tests/cli/unbundle-print-module1.wat.stdout renamed to tests/cli/unbundle-print-module.wat.read1.stdout

@@ -1,4 +1,5 @@
-/// RUN: component wit % --out-dir %tmpdir | component wit %tmpdir
+/// RUN[gen]: component wit % --out-dir %tmpdir
+/// RUN[read]: component wit %tmpdir
 package foo:root;
 
 package a:b {