Reorganize wasi-misc-tests. (#575)

* Reorganize wasi-misc-tests.

Move wasi-misc-tests out of wasi-common, to break a dependency cycle;
previously, wasmtime-* depended on wasi-common, but wasi-common
dev-dependended on wasmtime-*.

Now, wasi-common no longer dev-depends on wasmtime-*; instead, the
tests are in their own crate which depends on wasi-common and on
wasmtime-*.

Also, rename wasi-misc-tests to wasi-tests for simplicity.

This also removes the "wasm_tests" feature; it's replaced by the
"test-programs" feature.

* Update the CI script to use the new feature name.

* Update the CI script to use the new feature name in one more place.

* Change a `write!` to a `writeln!`.

crates/test-programs/wasi-tests/src/bin/isatty.rs

@@ -0,0 +1,62 @@
+use more_asserts::assert_gt;
+use std::{env, process};
+use wasi::wasi_unstable;
+use wasi_tests::open_scratch_directory;
+use wasi_tests::utils::{cleanup_file, close_fd};
+use wasi_tests::wasi_wrappers::wasi_path_open;
+
+unsafe fn test_isatty(dir_fd: wasi_unstable::Fd) {
+    // Create a file in the scratch directory and test if it's a tty.
+    let mut file_fd: wasi_unstable::Fd = wasi_unstable::Fd::max_value() - 1;
+    let status = wasi_path_open(
+        dir_fd,
+        0,
+        "file",
+        wasi_unstable::O_CREAT,
+        0,
+        0,
+        0,
+        &mut file_fd,
+    );
+    assert_eq!(
+        status,
+        wasi_unstable::raw::__WASI_ESUCCESS,
+        "opening a file"
+    );
+    assert_gt!(
+        file_fd,
+        libc::STDERR_FILENO as wasi_unstable::Fd,
+        "file descriptor range check",
+    );
+    assert_eq!(
+        libc::isatty(file_fd as std::os::raw::c_int),
+        0,
+        "file is a tty"
+    );
+    close_fd(file_fd);
+
+    cleanup_file(dir_fd, "file");
+}
+
+fn main() {
+    let mut args = env::args();
+    let prog = args.next().unwrap();
+    let arg = if let Some(arg) = args.next() {
+        arg
+    } else {
+        eprintln!("usage: {} <scratch directory>", prog);
+        process::exit(1);
+    };
+
+    // Open scratch directory
+    let dir_fd = match open_scratch_directory(&arg) {
+        Ok(dir_fd) => dir_fd,
+        Err(err) => {
+            eprintln!("{}", err);
+            process::exit(1)
+        }
+    };
+
+    // Run the tests.
+    unsafe { test_isatty(dir_fd) }
+}