diff --git a/crates/test-programs/wasi-tests/src/bin/close_preopen.rs b/crates/test-programs/wasi-tests/src/bin/close_preopen.rs
index 26ca315465..7dabc044df 100644
--- a/crates/test-programs/wasi-tests/src/bin/close_preopen.rs
+++ b/crates/test-programs/wasi-tests/src/bin/close_preopen.rs
@@ -1,6 +1,6 @@
 use more_asserts::assert_gt;
 use std::{env, process};
-use wasi_tests::open_scratch_directory;
+use wasi_tests::{assert_errno, open_scratch_directory};
 
 unsafe fn test_close_preopen(dir_fd: wasi::Fd) {
     let pre_fd: wasi::Fd = (libc::STDERR_FILENO + 1) as wasi::Fd;
@@ -17,12 +17,11 @@ unsafe fn test_close_preopen(dir_fd: wasi::Fd) {
     );
 
     // Try to renumber over a preopened directory handle.
-    assert_eq!(
+    assert_errno!(
         wasi::fd_renumber(dir_fd, pre_fd)
             .expect_err("renumbering over a preopened file descriptor")
             .raw_error(),
         wasi::ERRNO_NOTSUP,
-        "errno should be ERRNO_NOTSUP",
     );
 
     // Ensure that dir_fd is still open.
@@ -34,12 +33,11 @@ unsafe fn test_close_preopen(dir_fd: wasi::Fd) {
     );
 
     // Try to renumber a preopened directory handle.
-    assert_eq!(
+    assert_errno!(
         wasi::fd_renumber(pre_fd, dir_fd)
             .expect_err("renumbering over a preopened file descriptor")
             .raw_error(),
         wasi::ERRNO_NOTSUP,
-        "errno should be ERRNO_NOTSUP",
     );
 
     // Ensure that dir_fd is still open.
diff --git a/crates/test-programs/wasi-tests/src/bin/dangling_symlink.rs b/crates/test-programs/wasi-tests/src/bin/dangling_symlink.rs
index 47e2e3d580..4448ab9abd 100644
--- a/crates/test-programs/wasi-tests/src/bin/dangling_symlink.rs
+++ b/crates/test-programs/wasi-tests/src/bin/dangling_symlink.rs
@@ -1,26 +1,25 @@
 use std::{env, process};
-use wasi_tests::open_scratch_directory;
+use wasi_tests::{assert_errno, open_scratch_directory};
 
 unsafe fn test_dangling_symlink(dir_fd: wasi::Fd) {
     // First create a dangling symlink.
     wasi::path_symlink("target", dir_fd, "symlink").expect("creating a symlink");
 
     // Try to open it as a directory with O_NOFOLLOW.
-    let dir_open_errno = wasi::path_open(dir_fd, 0, "symlink", wasi::OFLAGS_DIRECTORY, 0, 0, 0)
-        .expect_err("opening a dangling symlink as a directory")
-        .raw_error();
-    assert!(
-        dir_open_errno == wasi::ERRNO_NOTDIR || dir_open_errno == wasi::ERRNO_LOOP,
-        "errno should be ERRNO_NOTDIR or ERRNO_LOOP",
+    assert_errno!(
+        wasi::path_open(dir_fd, 0, "symlink", wasi::OFLAGS_DIRECTORY, 0, 0, 0)
+            .expect_err("opening a dangling symlink as a directory")
+            .raw_error(),
+        wasi::ERRNO_NOTDIR,
+        wasi::ERRNO_LOOP
     );
 
     // Try to open it as a file with O_NOFOLLOW.
-    assert_eq!(
+    assert_errno!(
         wasi::path_open(dir_fd, 0, "symlink", 0, 0, 0, 0)
             .expect_err("opening a dangling symlink as a file")
             .raw_error(),
         wasi::ERRNO_LOOP,
-        "errno should be ERRNO_LOOP",
     );
 
     // Clean up.
diff --git a/crates/test-programs/wasi-tests/src/bin/directory_seek.rs b/crates/test-programs/wasi-tests/src/bin/directory_seek.rs
index fc6cd3eb03..a8d5c5b740 100644
--- a/crates/test-programs/wasi-tests/src/bin/directory_seek.rs
+++ b/crates/test-programs/wasi-tests/src/bin/directory_seek.rs
@@ -1,6 +1,6 @@
 use more_asserts::assert_gt;
 use std::{env, process};
-use wasi_tests::open_scratch_directory;
+use wasi_tests::{assert_errno, open_scratch_directory};
 
 unsafe fn test_directory_seek(dir_fd: wasi::Fd) {
     // Create a directory in the scratch directory.
@@ -24,12 +24,11 @@ unsafe fn test_directory_seek(dir_fd: wasi::Fd) {
     );
 
     // Attempt to seek.
-    assert_eq!(
+    assert_errno!(
         wasi::fd_seek(fd, 0, wasi::WHENCE_CUR)
             .expect_err("seek on a directory")
             .raw_error(),
         wasi::ERRNO_BADF,
-        "errno should be BADF"
     );
 
     // Check if we obtained the right to seek.
diff --git a/crates/test-programs/wasi-tests/src/bin/file_seek_tell.rs b/crates/test-programs/wasi-tests/src/bin/file_seek_tell.rs
index b5d43a278a..1d256cb7aa 100644
--- a/crates/test-programs/wasi-tests/src/bin/file_seek_tell.rs
+++ b/crates/test-programs/wasi-tests/src/bin/file_seek_tell.rs
@@ -1,6 +1,6 @@
 use more_asserts::assert_gt;
 use std::{env, process};
-use wasi_tests::open_scratch_directory;
+use wasi_tests::{assert_errno, open_scratch_directory};
 
 unsafe fn test_file_seek_tell(dir_fd: wasi::Fd) {
     // Create a file in the scratch directory.
@@ -57,16 +57,16 @@ unsafe fn test_file_seek_tell(dir_fd: wasi::Fd) {
     wasi::fd_seek(file_fd, 1000, wasi::WHENCE_CUR).expect("seeking beyond the end of the file");
 
     // Seek before byte 0 is an error though
-    assert_eq!(
+    assert_errno!(
         wasi::fd_seek(file_fd, -2000, wasi::WHENCE_CUR)
             .expect_err("seeking before byte 0 should be an error")
             .raw_error(),
         wasi::ERRNO_INVAL,
-        "errno should be ERRNO_INVAL",
     );
 
     // Check that fd_read properly updates the file offset
-    wasi::fd_seek(file_fd, 0, wasi::WHENCE_SET).expect("seeking to the beginning of the file again");
+    wasi::fd_seek(file_fd, 0, wasi::WHENCE_SET)
+        .expect("seeking to the beginning of the file again");
 
     let buffer = &mut [0u8; 100];
     let iovec = wasi::Iovec {
diff --git a/crates/test-programs/wasi-tests/src/bin/interesting_paths.rs b/crates/test-programs/wasi-tests/src/bin/interesting_paths.rs
index b0c12b2e2c..2ffde029fa 100644
--- a/crates/test-programs/wasi-tests/src/bin/interesting_paths.rs
+++ b/crates/test-programs/wasi-tests/src/bin/interesting_paths.rs
@@ -1,6 +1,6 @@
 use more_asserts::assert_gt;
 use std::{env, process};
-use wasi_tests::{create_file, open_scratch_directory};
+use wasi_tests::{assert_errno, create_file, open_scratch_directory};
 
 unsafe fn test_interesting_paths(dir_fd: wasi::Fd, arg: &str) {
     // Create a directory in the scratch directory.
@@ -13,12 +13,11 @@ unsafe fn test_interesting_paths(dir_fd: wasi::Fd, arg: &str) {
     create_file(dir_fd, "dir/nested/file");
 
     // Now open it with an absolute path.
-    assert_eq!(
+    assert_errno!(
         wasi::path_open(dir_fd, 0, "/dir/nested/file", 0, 0, 0, 0)
             .expect_err("opening a file with an absolute path")
             .raw_error(),
         wasi::ERRNO_PERM,
-        "errno should be ERRNO_PERM"
     );
 
     // Now open it with a path containing "..".
@@ -40,34 +39,29 @@ unsafe fn test_interesting_paths(dir_fd: wasi::Fd, arg: &str) {
     wasi::fd_close(file_fd).expect("closing a file");
 
     // Now open it with a trailing NUL.
-    assert_eq!(
+    assert_errno!(
         wasi::path_open(dir_fd, 0, "dir/nested/file\0", 0, 0, 0, 0)
             .expect_err("opening a file with a trailing NUL")
             .raw_error(),
         wasi::ERRNO_ILSEQ,
-        "errno should be ERRNO_ILSEQ",
     );
 
     // Now open it with a trailing slash.
-    let one_trailing_slash_errno = wasi::path_open(dir_fd, 0, "dir/nested/file/", 0, 0, 0, 0)
-        .expect_err("opening a file with a trailing slash should fail")
-        .raw_error();
-    assert!(
-        one_trailing_slash_errno == wasi::ERRNO_NOTDIR
-            || one_trailing_slash_errno == wasi::ERRNO_NOENT,
-        "errno should be ERRNO_NOTDIR or ERRNO_NOENT, got {}",
-        one_trailing_slash_errno
+    assert_errno!(
+        wasi::path_open(dir_fd, 0, "dir/nested/file/", 0, 0, 0, 0)
+            .expect_err("opening a file with a trailing slash should fail")
+            .raw_error(),
+        wasi::ERRNO_NOTDIR,
+        wasi::ERRNO_NOENT,
     );
 
     // Now open it with trailing slashes.
-    let multi_trailing_slash_errno = wasi::path_open(dir_fd, 0, "dir/nested/file///", 0, 0, 0, 0)
-        .expect_err("opening a file with trailing slashes should fail")
-        .raw_error();
-    assert!(
-        multi_trailing_slash_errno == wasi::ERRNO_NOTDIR
-            || multi_trailing_slash_errno == wasi::ERRNO_NOENT,
-        "errno should be ERRNO_NOTDIR or ERRNO_NOENT, got {}",
-        multi_trailing_slash_errno,
+    assert_errno!(
+        wasi::path_open(dir_fd, 0, "dir/nested/file///", 0, 0, 0, 0)
+            .expect_err("opening a file with trailing slashes should fail")
+            .raw_error(),
+        wasi::ERRNO_NOTDIR,
+        wasi::ERRNO_NOENT,
     );
 
     // Now open the directory with a trailing slash.
@@ -92,12 +86,11 @@ unsafe fn test_interesting_paths(dir_fd: wasi::Fd, arg: &str) {
 
     // Now open it with a path containing too many ".."s.
     let bad_path = format!("dir/nested/../../../{}/dir/nested/file", arg);
-    assert_eq!(
+    assert_errno!(
         wasi::path_open(dir_fd, 0, &bad_path, 0, 0, 0, 0)
             .expect_err("opening a file with too many \"..\"s in the path should fail")
             .raw_error(),
         wasi::ERRNO_PERM,
-        "errno should be ERRNO_PERM",
     );
     wasi::path_unlink_file(dir_fd, "dir/nested/file")
         .expect("unlink_file on a symlink should succeed");
diff --git a/crates/test-programs/wasi-tests/src/bin/nofollow_errors.rs b/crates/test-programs/wasi-tests/src/bin/nofollow_errors.rs
index a81944862c..dd5aaf71e9 100644
--- a/crates/test-programs/wasi-tests/src/bin/nofollow_errors.rs
+++ b/crates/test-programs/wasi-tests/src/bin/nofollow_errors.rs
@@ -1,7 +1,7 @@
 use libc;
 use more_asserts::assert_gt;
 use std::{env, process};
-use wasi_tests::open_scratch_directory;
+use wasi_tests::{assert_errno, open_scratch_directory};
 
 unsafe fn test_nofollow_errors(dir_fd: wasi::Fd) {
     // Create a directory for the symlink to point to.
@@ -11,23 +11,21 @@ unsafe fn test_nofollow_errors(dir_fd: wasi::Fd) {
     wasi::path_symlink("target", dir_fd, "symlink").expect("creating a symlink");
 
     // Try to open it as a directory with O_NOFOLLOW again.
-    let dir_open_errno = wasi::path_open(dir_fd, 0, "symlink", wasi::OFLAGS_DIRECTORY, 0, 0, 0)
-        .expect_err("opening a directory symlink as a directory should fail")
-        .raw_error();
-    assert!(
-        dir_open_errno == wasi::ERRNO_LOOP || dir_open_errno == wasi::ERRNO_NOTDIR,
-        "errno should be ERRNO_LOOP or ERRNO_NOTDIR, got {}",
-        dir_open_errno,
+    assert_errno!(
+        wasi::path_open(dir_fd, 0, "symlink", wasi::OFLAGS_DIRECTORY, 0, 0, 0)
+            .expect_err("opening a directory symlink as a directory should fail")
+            .raw_error(),
+        wasi::ERRNO_LOOP,
+        wasi::ERRNO_NOTDIR,
     );
 
     // Try to open it with just O_NOFOLLOW.
-    let file_open_errno = wasi::path_open(dir_fd, 0, "symlink", 0, 0, 0, 0)
-        .expect_err("opening a symlink with O_NOFOLLOW should fail")
-        .raw_error();
-    assert!(
-        file_open_errno == wasi::ERRNO_LOOP || file_open_errno == wasi::ERRNO_ACCES,
-        "errno should be ERRNO_LOOP or ERRNO_ACCES, got {}",
-        file_open_errno,
+    assert_errno!(
+        wasi::path_open(dir_fd, 0, "symlink", 0, 0, 0, 0)
+            .expect_err("opening a symlink with O_NOFOLLOW should fail")
+            .raw_error(),
+        wasi::ERRNO_LOOP,
+        wasi::ERRNO_ACCES,
     );
 
     // Try to open it as a directory without O_NOFOLLOW.
@@ -59,25 +57,24 @@ unsafe fn test_nofollow_errors(dir_fd: wasi::Fd) {
     wasi::path_symlink("target", dir_fd, "symlink").expect("creating a symlink");
 
     // Try to open it as a directory with O_NOFOLLOW again.
-    let dir_open_errno = wasi::path_open(dir_fd, 0, "symlink", wasi::OFLAGS_DIRECTORY, 0, 0, 0)
-        .expect_err("opening a directory symlink as a directory should fail")
-        .raw_error();
-    assert!(
-        dir_open_errno == wasi::ERRNO_LOOP || dir_open_errno == wasi::ERRNO_NOTDIR,
-        "errno should be ERRNO_LOOP or ERRNO_NOTDIR",
+    assert_errno!(
+        wasi::path_open(dir_fd, 0, "symlink", wasi::OFLAGS_DIRECTORY, 0, 0, 0)
+            .expect_err("opening a directory symlink as a directory should fail")
+            .raw_error(),
+        wasi::ERRNO_LOOP,
+        wasi::ERRNO_NOTDIR
     );
 
     // Try to open it with just O_NOFOLLOW.
-    assert_eq!(
+    assert_errno!(
         wasi::path_open(dir_fd, 0, "symlink", 0, 0, 0, 0)
             .expect_err("opening a symlink with NOFOLLOW should fail")
             .raw_error(),
         wasi::ERRNO_LOOP,
-        "errno should be ERRNO_LOOP",
     );
 
     // Try to open it as a directory without O_NOFOLLOW.
-    assert_eq!(
+    assert_errno!(
         wasi::path_open(
             dir_fd,
             wasi::LOOKUPFLAGS_SYMLINK_FOLLOW,
@@ -90,7 +87,6 @@ unsafe fn test_nofollow_errors(dir_fd: wasi::Fd) {
         .expect_err("opening a symlink to a file as a directory")
         .raw_error(),
         wasi::ERRNO_NOTDIR,
-        "errno should be ERRNO_NOTDIR",
     );
 
     // Clean up.
diff --git a/crates/test-programs/wasi-tests/src/bin/path_filestat.rs b/crates/test-programs/wasi-tests/src/bin/path_filestat.rs
index efcc6a46fa..e6c8f19569 100644
--- a/crates/test-programs/wasi-tests/src/bin/path_filestat.rs
+++ b/crates/test-programs/wasi-tests/src/bin/path_filestat.rs
@@ -1,6 +1,6 @@
 use more_asserts::assert_gt;
 use std::{env, process};
-use wasi_tests::open_scratch_directory;
+use wasi_tests::{assert_errno, open_scratch_directory};
 
 unsafe fn test_path_filestat(dir_fd: wasi::Fd) {
     let mut fdstat = wasi::fd_fdstat_get(dir_fd).expect("fd_fdstat_get");
@@ -58,7 +58,7 @@ unsafe fn test_path_filestat(dir_fd: wasi::Fd) {
         .expect("reading file stats after path_filestat_set_times");
     assert_eq!(modified_file_stat.mtim, new_mtim, "mtim should change");
 
-    assert_eq!(
+    assert_errno!(
         wasi::path_filestat_set_times(
             dir_fd,
             0,
@@ -69,8 +69,7 @@ unsafe fn test_path_filestat(dir_fd: wasi::Fd) {
         )
         .expect_err("MTIM and MTIM_NOW can't both be set")
         .raw_error(),
-        wasi::ERRNO_INVAL,
-        "errno should be ERRNO_INVAL"
+        wasi::ERRNO_INVAL
     );
 
     // check if the times were untouched
@@ -82,7 +81,7 @@ unsafe fn test_path_filestat(dir_fd: wasi::Fd) {
     );
 
     // Invalid arguments to set_times:
-    assert_eq!(
+    assert_errno!(
         wasi::path_filestat_set_times(
             dir_fd,
             0,
@@ -94,7 +93,6 @@ unsafe fn test_path_filestat(dir_fd: wasi::Fd) {
         .expect_err("ATIM & ATIM_NOW can't both be set")
         .raw_error(),
         wasi::ERRNO_INVAL,
-        "errno should be ERRNO_INVAL"
     );
 
     wasi::fd_close(file_fd).expect("closing a file");
diff --git a/crates/test-programs/wasi-tests/src/bin/path_link.rs b/crates/test-programs/wasi-tests/src/bin/path_link.rs
index 16d827e8dd..776c1ad036 100644
--- a/crates/test-programs/wasi-tests/src/bin/path_link.rs
+++ b/crates/test-programs/wasi-tests/src/bin/path_link.rs
@@ -1,6 +1,6 @@
 use more_asserts::assert_gt;
 use std::{env, process};
-use wasi_tests::{create_file, open_scratch_directory};
+use wasi_tests::{assert_errno, create_file, open_scratch_directory};
 
 const TEST_RIGHTS: wasi::Rights = wasi::RIGHTS_FD_READ
     | wasi::RIGHTS_PATH_LINK_SOURCE
@@ -102,33 +102,30 @@ unsafe fn test_path_link(dir_fd: wasi::Fd) {
     // Create a link to a path that already exists
     create_file(dir_fd, "link");
 
-    assert_eq!(
+    assert_errno!(
         wasi::path_link(dir_fd, 0, "file", dir_fd, "link")
             .expect_err("creating a link to existing path should fail")
             .raw_error(),
-        wasi::ERRNO_EXIST,
-        "errno should be ERRNO_EXIST"
+        wasi::ERRNO_EXIST
     );
     wasi::path_unlink_file(dir_fd, "link").expect("removing a file");
 
     // Create a link to itself
-    assert_eq!(
+    assert_errno!(
         wasi::path_link(dir_fd, 0, "file", dir_fd, "file")
             .expect_err("creating a link to itself should fail")
             .raw_error(),
-        wasi::ERRNO_EXIST,
-        "errno should be ERRNO_EXIST"
+        wasi::ERRNO_EXIST
     );
 
     // Create a link where target is a directory
     wasi::path_create_directory(dir_fd, "link").expect("creating a dir");
 
-    assert_eq!(
+    assert_errno!(
         wasi::path_link(dir_fd, 0, "file", dir_fd, "link")
             .expect_err("creating a link where target is a directory should fail")
             .raw_error(),
-        wasi::ERRNO_EXIST,
-        "errno should be ERRNO_EXIST"
+        wasi::ERRNO_EXIST
     );
     wasi::path_remove_directory(dir_fd, "link").expect("removing a dir");
 
@@ -136,23 +133,22 @@ unsafe fn test_path_link(dir_fd: wasi::Fd) {
     wasi::path_create_directory(dir_fd, "subdir").expect("creating a subdirectory");
     let subdir_fd = create_or_open(dir_fd, "subdir", wasi::OFLAGS_DIRECTORY);
 
-    let path_link_errno = wasi::path_link(dir_fd, 0, "subdir", dir_fd, "link")
-        .expect_err("creating a link to a directory should fail")
-        .raw_error();
-    assert!(
-        path_link_errno == wasi::ERRNO_PERM || path_link_errno == wasi::ERRNO_ACCES,
-        "errno should be ERRNO_PERM or ERRNO_ACCES"
+    assert_errno!(
+        wasi::path_link(dir_fd, 0, "subdir", dir_fd, "link")
+            .expect_err("creating a link to a directory should fail")
+            .raw_error(),
+        wasi::ERRNO_PERM,
+        wasi::ERRNO_ACCES
     );
     wasi::fd_close(subdir_fd).expect("close subdir before deleting it");
     wasi::path_remove_directory(dir_fd, "subdir").expect("removing a subdirectory");
 
     // Create a link to a file with trailing slash
-    assert_eq!(
+    assert_errno!(
         wasi::path_link(dir_fd, 0, "file", dir_fd, "link/")
             .expect_err("creating a link to a file with trailing slash should fail")
             .raw_error(),
         wasi::ERRNO_NOENT,
-        "errno should be ERRNO_NOENT"
     );
 
     // XXX windows doesnt support dangling symlinks - rest of file
@@ -176,12 +172,11 @@ unsafe fn test_path_link(dir_fd: wasi::Fd) {
     // Create a link where target is a dangling symlink
     wasi::path_symlink("target", dir_fd, "symlink").expect("creating a dangling symlink");
 
-    assert_eq!(
+    assert_errno!(
         wasi::path_link(dir_fd, 0, "file", dir_fd, "symlink")
             .expect_err("creating a link where target is a dangling symlink")
             .raw_error(),
         wasi::ERRNO_EXIST,
-        "errno should be ERRNO_EXIST"
     );
     wasi::path_unlink_file(dir_fd, "symlink").expect("removing a symlink");
 
@@ -189,7 +184,7 @@ unsafe fn test_path_link(dir_fd: wasi::Fd) {
     wasi::path_symlink("target", dir_fd, "symlink").expect("creating a dangling symlink");
 
     // Symlink following with path_link is rejected
-    assert_eq!(
+    assert_errno!(
         wasi::path_link(
             dir_fd,
             wasi::LOOKUPFLAGS_SYMLINK_FOLLOW,
@@ -200,7 +195,6 @@ unsafe fn test_path_link(dir_fd: wasi::Fd) {
         .expect_err("calling path_link with LOOKUPFLAGS_SYMLINK_FOLLOW should fail")
         .raw_error(),
         wasi::ERRNO_INVAL,
-        "errno should be ERRNO_INVAL"
     );
 
     // Clean up.
diff --git a/crates/test-programs/wasi-tests/src/bin/path_open_create_existing.rs b/crates/test-programs/wasi-tests/src/bin/path_open_create_existing.rs
index 11e7fc4c99..b9279b029d 100644
--- a/crates/test-programs/wasi-tests/src/bin/path_open_create_existing.rs
+++ b/crates/test-programs/wasi-tests/src/bin/path_open_create_existing.rs
@@ -1,9 +1,9 @@
 use std::{env, process};
-use wasi_tests::{create_file, open_scratch_directory};
+use wasi_tests::{assert_errno, create_file, open_scratch_directory};
 
 unsafe fn test_path_open_create_existing(dir_fd: wasi::Fd) {
     create_file(dir_fd, "file");
-    assert_eq!(
+    assert_errno!(
         wasi::path_open(
             dir_fd,
             0,
@@ -16,7 +16,6 @@ unsafe fn test_path_open_create_existing(dir_fd: wasi::Fd) {
         .expect_err("trying to create a file that already exists")
         .raw_error(),
         wasi::ERRNO_EXIST,
-        "errno should be ERRNO_EXIST"
     );
     wasi::path_unlink_file(dir_fd, "file").expect("removing a file");
 }
diff --git a/crates/test-programs/wasi-tests/src/bin/path_open_dirfd_not_dir.rs b/crates/test-programs/wasi-tests/src/bin/path_open_dirfd_not_dir.rs
index dd6e502361..09fdc34720 100644
--- a/crates/test-programs/wasi-tests/src/bin/path_open_dirfd_not_dir.rs
+++ b/crates/test-programs/wasi-tests/src/bin/path_open_dirfd_not_dir.rs
@@ -1,17 +1,16 @@
 use std::{env, process};
-use wasi_tests::open_scratch_directory;
+use wasi_tests::{assert_errno, open_scratch_directory};
 
 unsafe fn test_dirfd_not_dir(dir_fd: wasi::Fd) {
     // Open a file.
     let file_fd =
         wasi::path_open(dir_fd, 0, "file", wasi::OFLAGS_CREAT, 0, 0, 0).expect("opening a file");
     // Now try to open a file underneath it as if it were a directory.
-    assert_eq!(
+    assert_errno!(
         wasi::path_open(file_fd, 0, "foo", wasi::OFLAGS_CREAT, 0, 0, 0)
             .expect_err("non-directory base fd should get ERRNO_NOTDIR")
             .raw_error(),
         wasi::ERRNO_NOTDIR,
-        "errno should be ERRNO_NOTDIR"
     );
     wasi::fd_close(file_fd).expect("closing a file");
 }
diff --git a/crates/test-programs/wasi-tests/src/bin/path_open_missing.rs b/crates/test-programs/wasi-tests/src/bin/path_open_missing.rs
index 410b602c45..8074090b8d 100644
--- a/crates/test-programs/wasi-tests/src/bin/path_open_missing.rs
+++ b/crates/test-programs/wasi-tests/src/bin/path_open_missing.rs
@@ -1,21 +1,15 @@
 use std::{env, process};
-use wasi_tests::{open_scratch_directory};
+use wasi_tests::{assert_errno, open_scratch_directory};
 
 unsafe fn test_path_open_missing(dir_fd: wasi::Fd) {
-    assert_eq!(
+    assert_errno!(
         wasi::path_open(
-            dir_fd,
-            0,
-            "file",
-            0, // not passing O_CREAT here
-            0,
-            0,
-            0,
+            dir_fd, 0, "file", 0, // not passing O_CREAT here
+            0, 0, 0,
         )
         .expect_err("trying to open a file that doesn't exist")
         .raw_error(),
-        wasi::ERRNO_NOENT,
-        "errno should be ERRNO_NOENT"
+        wasi::ERRNO_NOENT
     );
 }
 
diff --git a/crates/test-programs/wasi-tests/src/bin/path_open_read_without_rights.rs b/crates/test-programs/wasi-tests/src/bin/path_open_read_without_rights.rs
index 26113c08c8..c67fbe1280 100644
--- a/crates/test-programs/wasi-tests/src/bin/path_open_read_without_rights.rs
+++ b/crates/test-programs/wasi-tests/src/bin/path_open_read_without_rights.rs
@@ -1,6 +1,5 @@
 use std::{env, process};
-use wasi_tests::open_scratch_directory;
-use wasi_tests::{create_file, drop_rights, fd_get_rights};
+use wasi_tests::{assert_errno, create_file, drop_rights, fd_get_rights, open_scratch_directory};
 
 const TEST_FILENAME: &'static str = "file";
 
@@ -27,12 +26,11 @@ unsafe fn try_read_file(dir_fd: wasi::Fd) {
     };
     // Since we no longer have the right to fd_read, trying to read a file
     // should be an error.
-    assert_eq!(
+    assert_errno!(
         wasi::fd_read(fd, &[iovec])
             .expect_err("reading bytes from file should fail")
             .raw_error(),
-        wasi::ERRNO_NOTCAPABLE,
-        "the errno should be ENOTCAPABLE"
+        wasi::ERRNO_NOTCAPABLE
     );
 }
 
diff --git a/crates/test-programs/wasi-tests/src/bin/path_rename.rs b/crates/test-programs/wasi-tests/src/bin/path_rename.rs
index 37a9bf8169..950c35a731 100644
--- a/crates/test-programs/wasi-tests/src/bin/path_rename.rs
+++ b/crates/test-programs/wasi-tests/src/bin/path_rename.rs
@@ -1,6 +1,6 @@
 use more_asserts::assert_gt;
 use std::{env, process};
-use wasi_tests::{create_file, open_scratch_directory};
+use wasi_tests::{assert_errno, create_file, open_scratch_directory};
 
 unsafe fn test_path_rename(dir_fd: wasi::Fd) {
     // First, try renaming a dir to nonexistent path
@@ -11,12 +11,11 @@ unsafe fn test_path_rename(dir_fd: wasi::Fd) {
     wasi::path_rename(dir_fd, "source", dir_fd, "target").expect("renaming a directory");
 
     // Check that source directory doesn't exist anymore
-    assert_eq!(
+    assert_errno!(
         wasi::path_open(dir_fd, 0, "source", wasi::OFLAGS_DIRECTORY, 0, 0, 0)
             .expect_err("opening a nonexistent path as a directory should fail")
             .raw_error(),
-        wasi::ERRNO_NOENT,
-        "errno should be ERRNO_NOENT"
+        wasi::ERRNO_NOENT
     );
 
     // Check that target directory exists
@@ -37,12 +36,11 @@ unsafe fn test_path_rename(dir_fd: wasi::Fd) {
     wasi::path_rename(dir_fd, "source", dir_fd, "target").expect("renaming a directory");
 
     // Check that source directory doesn't exist anymore
-    assert_eq!(
+    assert_errno!(
         wasi::path_open(dir_fd, 0, "source", wasi::OFLAGS_DIRECTORY, 0, 0, 0)
             .expect_err("opening a nonexistent path as a directory")
             .raw_error(),
-        wasi::ERRNO_NOENT,
-        "errno should be ERRNO_NOENT"
+        wasi::ERRNO_NOENT
     );
 
     // Check that target directory exists
@@ -62,21 +60,19 @@ unsafe fn test_path_rename(dir_fd: wasi::Fd) {
     wasi::path_create_directory(dir_fd, "target").expect("creating a directory");
     create_file(dir_fd, "target/file");
 
-    assert_eq!(
+    assert_errno!(
         wasi::path_rename(dir_fd, "source", dir_fd, "target")
             .expect_err("renaming directory to a nonempty directory")
             .raw_error(),
-        wasi::ERRNO_NOTEMPTY,
-        "errno should be ERRNO_NOTEMPTY"
+        wasi::ERRNO_NOTEMPTY
     );
 
     // Try renaming dir to a file
-    assert_eq!(
+    assert_errno!(
         wasi::path_rename(dir_fd, "source", dir_fd, "target/file")
             .expect_err("renaming a directory to a file")
             .raw_error(),
-        wasi::ERRNO_NOTDIR,
-        "errno should be ERRNO_NOTDIR"
+        wasi::ERRNO_NOTDIR
     );
 
     wasi::path_unlink_file(dir_fd, "target/file").expect("removing a file");
@@ -88,12 +84,11 @@ unsafe fn test_path_rename(dir_fd: wasi::Fd) {
     wasi::path_rename(dir_fd, "source", dir_fd, "target").expect("renaming a file");
 
     // Check that source file doesn't exist anymore
-    assert_eq!(
+    assert_errno!(
         wasi::path_open(dir_fd, 0, "source", 0, 0, 0, 0)
             .expect_err("opening a nonexistent path should fail")
             .raw_error(),
-        wasi::ERRNO_NOENT,
-        "errno should be ERRNO_NOENT"
+        wasi::ERRNO_NOENT
     );
 
     // Check that target file exists
@@ -115,12 +110,11 @@ unsafe fn test_path_rename(dir_fd: wasi::Fd) {
         .expect("renaming file to another existing file");
 
     // Check that source file doesn't exist anymore
-    assert_eq!(
+    assert_errno!(
         wasi::path_open(dir_fd, 0, "source", 0, 0, 0, 0)
             .expect_err("opening a nonexistent path")
             .raw_error(),
-        wasi::ERRNO_NOENT,
-        "errno should be ERRNO_NOENT"
+        wasi::ERRNO_NOENT
     );
 
     // Check that target file exists
@@ -139,12 +133,11 @@ unsafe fn test_path_rename(dir_fd: wasi::Fd) {
     create_file(dir_fd, "source");
     wasi::path_create_directory(dir_fd, "target").expect("creating a directory");
 
-    assert_eq!(
+    assert_errno!(
         wasi::path_rename(dir_fd, "source", dir_fd, "target")
             .expect_err("renaming a file to existing directory should fail")
             .raw_error(),
-        wasi::ERRNO_ISDIR,
-        "errno should be ERRNO_ISDIR"
+        wasi::ERRNO_ISDIR
     );
 
     wasi::path_remove_directory(dir_fd, "target").expect("removing a directory");
diff --git a/crates/test-programs/wasi-tests/src/bin/path_rename_file_trailing_slashes.rs b/crates/test-programs/wasi-tests/src/bin/path_rename_file_trailing_slashes.rs
index 9d22f4d0c0..67c6796098 100644
--- a/crates/test-programs/wasi-tests/src/bin/path_rename_file_trailing_slashes.rs
+++ b/crates/test-programs/wasi-tests/src/bin/path_rename_file_trailing_slashes.rs
@@ -1,5 +1,5 @@
 use std::{env, process};
-use wasi_tests::{create_file, open_scratch_directory};
+use wasi_tests::{assert_errno, create_file, open_scratch_directory};
 
 unsafe fn test_path_rename_trailing_slashes(dir_fd: wasi::Fd) {
     // Test renaming a file with a trailing slash in the name.
@@ -9,26 +9,23 @@ unsafe fn test_path_rename_trailing_slashes(dir_fd: wasi::Fd) {
         .expect("no trailing slashes rename works");
     wasi::path_rename(dir_fd, "target", dir_fd, "source").expect("rename it back to source");
 
-    assert_eq!(
+    assert_errno!(
         wasi::path_rename(dir_fd, "source/", dir_fd, "target")
             .expect_err("renaming a file with a trailing slash in the source name should fail")
             .raw_error(),
         wasi::ERRNO_NOTDIR,
-        "errno should be ERRNO_NOTDIR"
     );
-    assert_eq!(
+    assert_errno!(
         wasi::path_rename(dir_fd, "source", dir_fd, "target/")
             .expect_err("renaming a file with a trailing slash in the destination name should fail")
             .raw_error(),
         wasi::ERRNO_NOTDIR,
-        "errno should be ERRNO_NOTDIR"
     );
-    assert_eq!(
+    assert_errno!(
         wasi::path_rename(dir_fd, "source/", dir_fd, "target/")
             .expect_err("renaming a file with a trailing slash in the source and destination names should fail")
             .raw_error(),
         wasi::ERRNO_NOTDIR,
-        "errno should be ERRNO_NOTDIR"
     );
     wasi::path_unlink_file(dir_fd, "source").expect("removing a file");
 }
diff --git a/crates/test-programs/wasi-tests/src/bin/path_symlink_trailing_slashes.rs b/crates/test-programs/wasi-tests/src/bin/path_symlink_trailing_slashes.rs
index 0b285c3d56..748b8bd95d 100644
--- a/crates/test-programs/wasi-tests/src/bin/path_symlink_trailing_slashes.rs
+++ b/crates/test-programs/wasi-tests/src/bin/path_symlink_trailing_slashes.rs
@@ -1,15 +1,14 @@
 use std::{env, process};
-use wasi_tests::{create_file, open_scratch_directory};
+use wasi_tests::{assert_errno, create_file, open_scratch_directory};
 
 unsafe fn test_path_symlink_trailing_slashes(dir_fd: wasi::Fd) {
     // XXX following section invalid on windows because its a dangling symlink
     // Dangling symlink: Link destination shouldn't end with a slash.
-    assert_eq!(
+    assert_errno!(
         wasi::path_symlink("source", dir_fd, "target/")
             .expect_err("link destination ending with a slash should fail")
             .raw_error(),
         wasi::ERRNO_NOENT,
-        "errno should be ERRNO_NOENT"
     );
 
     // Dangling symlink: Without the trailing slash, this should succeed.
@@ -19,24 +18,22 @@ unsafe fn test_path_symlink_trailing_slashes(dir_fd: wasi::Fd) {
     // Link destination already exists, target has trailing slash.
     wasi::path_create_directory(dir_fd, "target").expect("creating a directory");
     // XXX windows gives NOENT
-    assert_eq!(
+    assert_errno!(
         wasi::path_symlink("source", dir_fd, "target/")
             .expect_err("link destination already exists")
             .raw_error(),
         wasi::ERRNO_EXIST,
-        "errno should be ERRNO_EXIST"
     );
     wasi::path_remove_directory(dir_fd, "target").expect("removing a directory");
 
     // Link destination already exists, target has no trailing slash.
     wasi::path_create_directory(dir_fd, "target").expect("creating a directory");
     // XXX windows gives NOENT
-    assert_eq!(
+    assert_errno!(
         wasi::path_symlink("source", dir_fd, "target")
             .expect_err("link destination already exists")
             .raw_error(),
         wasi::ERRNO_EXIST,
-        "errno should be ERRNO_EXIST"
     );
     wasi::path_remove_directory(dir_fd, "target").expect("removing a directory");
 
@@ -44,13 +41,12 @@ unsafe fn test_path_symlink_trailing_slashes(dir_fd: wasi::Fd) {
     create_file(dir_fd, "target");
 
     // XXX windows gives NOENT
-    let dir_symlink_errno = wasi::path_symlink("source", dir_fd, "target/")
-        .expect_err("link destination already exists")
-        .raw_error();
-    assert!(
-        dir_symlink_errno == wasi::ERRNO_EXIST || dir_symlink_errno == wasi::ERRNO_NOTDIR,
-        "errno should be ERRNO_EXIST or ERRNO_NOTDIR, got {}",
-        dir_symlink_errno
+    assert_errno!(
+        wasi::path_symlink("source", dir_fd, "target/")
+            .expect_err("link destination already exists")
+            .raw_error(),
+        wasi::ERRNO_EXIST,
+        wasi::ERRNO_NOTDIR,
     );
     wasi::path_unlink_file(dir_fd, "target").expect("removing a file");
 
@@ -58,12 +54,11 @@ unsafe fn test_path_symlink_trailing_slashes(dir_fd: wasi::Fd) {
     create_file(dir_fd, "target");
 
     // XXX windows gives NOENT
-    assert_eq!(
+    assert_errno!(
         wasi::path_symlink("source", dir_fd, "target")
             .expect_err("link destination already exists")
             .raw_error(),
         wasi::ERRNO_EXIST,
-        "errno should be ERRNO_EXIST"
     );
     wasi::path_unlink_file(dir_fd, "target").expect("removing a file");
 }
diff --git a/crates/test-programs/wasi-tests/src/bin/poll_oneoff.rs b/crates/test-programs/wasi-tests/src/bin/poll_oneoff.rs
index ec6668566a..2b1df93644 100644
--- a/crates/test-programs/wasi-tests/src/bin/poll_oneoff.rs
+++ b/crates/test-programs/wasi-tests/src/bin/poll_oneoff.rs
@@ -1,6 +1,6 @@
 use more_asserts::assert_gt;
 use std::{env, mem::MaybeUninit, process};
-use wasi_tests::open_scratch_directory;
+use wasi_tests::{assert_errno, open_scratch_directory};
 
 const CLOCK_ID: wasi::Userdata = 0x0123_45678;
 
@@ -17,12 +17,11 @@ unsafe fn poll_oneoff_impl(r#in: &[wasi::Subscription]) -> Result<Vec<wasi::Even
 unsafe fn test_empty_poll() {
     let r#in = [];
     let mut out: Vec<wasi::Event> = Vec::new();
-    let error = wasi::poll_oneoff(r#in.as_ptr(), out.as_mut_ptr(), r#in.len())
-        .expect_err("empty poll_oneoff should fail");
-    assert_eq!(
-        error.raw_error(),
+    assert_errno!(
+        wasi::poll_oneoff(r#in.as_ptr(), out.as_mut_ptr(), r#in.len())
+            .expect_err("empty poll_oneoff should fail")
+            .raw_error(),
         wasi::ERRNO_INVAL,
-        "error should be EINVAL"
     );
 }
 
@@ -43,11 +42,7 @@ unsafe fn test_timeout() {
     let out = poll_oneoff_impl(&r#in).unwrap();
     assert_eq!(out.len(), 1, "should return 1 event");
     let event = &out[0];
-    assert_eq!(
-        event.error,
-        wasi::ERRNO_SUCCESS,
-        "the event.error should be set to ESUCCESS"
-    );
+    assert_errno!(event.error, wasi::ERRNO_SUCCESS,);
     assert_eq!(
         event.r#type,
         wasi::EVENTTYPE_CLOCK,
@@ -89,11 +84,7 @@ unsafe fn test_fd_readwrite(fd: wasi::Fd, error_code: wasi::Errno) {
         out[0].userdata, 1,
         "the event.userdata should contain fd userdata specified by the user"
     );
-    assert_eq!(
-        out[0].error, error_code,
-        "the event.error should be set to {}",
-        error_code
-    );
+    assert_errno!(out[0].error, error_code);
     assert_eq!(
         out[0].r#type,
         wasi::EVENTTYPE_FD_READ,
@@ -103,11 +94,7 @@ unsafe fn test_fd_readwrite(fd: wasi::Fd, error_code: wasi::Errno) {
         out[1].userdata, 2,
         "the event.userdata should contain fd userdata specified by the user"
     );
-    assert_eq!(
-        out[1].error, error_code,
-        "the event.error should be set to {}",
-        error_code
-    );
+    assert_errno!(out[1].error, error_code);
     assert_eq!(
         out[1].r#type,
         wasi::EVENTTYPE_FD_WRITE,
diff --git a/crates/test-programs/wasi-tests/src/bin/poll_oneoff_stdio.rs b/crates/test-programs/wasi-tests/src/bin/poll_oneoff_stdio.rs
index 44caa47593..6a007c41ff 100644
--- a/crates/test-programs/wasi-tests/src/bin/poll_oneoff_stdio.rs
+++ b/crates/test-programs/wasi-tests/src/bin/poll_oneoff_stdio.rs
@@ -1,5 +1,5 @@
 use std::mem::MaybeUninit;
-use wasi_tests::{STDERR_FD, STDIN_FD, STDOUT_FD};
+use wasi_tests::{assert_errno, STDERR_FD, STDIN_FD, STDOUT_FD};
 
 const CLOCK_ID: wasi::Userdata = 0x0123_45678;
 
@@ -45,11 +45,7 @@ unsafe fn test_stdin_read() {
     let out = poll_oneoff_impl(&r#in).unwrap();
     assert_eq!(out.len(), 1, "should return 1 event");
     let event = &out[0];
-    assert_eq!(
-        event.error,
-        wasi::ERRNO_SUCCESS,
-        "the event.error should be set to ESUCCESS"
-    );
+    assert_errno!(event.error, wasi::ERRNO_SUCCESS);
     assert_eq!(
         event.r#type,
         wasi::EVENTTYPE_CLOCK,
@@ -94,11 +90,7 @@ unsafe fn test_stdout_stderr_write() {
         out[0].userdata, 1,
         "the event.userdata should contain fd userdata specified by the user"
     );
-    assert_eq!(
-        out[0].error,
-        wasi::ERRNO_SUCCESS,
-        "the event.error should be set to ERRNO_SUCCESS",
-    );
+    assert_errno!(out[0].error, wasi::ERRNO_SUCCESS);
     assert_eq!(
         out[0].r#type,
         wasi::EVENTTYPE_FD_WRITE,
@@ -108,11 +100,7 @@ unsafe fn test_stdout_stderr_write() {
         out[1].userdata, 2,
         "the event.userdata should contain fd userdata specified by the user"
     );
-    assert_eq!(
-        out[1].error,
-        wasi::ERRNO_SUCCESS,
-        "the event.error should be set to ERRNO_SUCCESS",
-    );
+    assert_errno!(out[1].error, wasi::ERRNO_SUCCESS);
     assert_eq!(
         out[1].r#type,
         wasi::EVENTTYPE_FD_WRITE,
diff --git a/crates/test-programs/wasi-tests/src/bin/readlink.rs b/crates/test-programs/wasi-tests/src/bin/readlink.rs
index c9c128286e..81fa33188d 100644
--- a/crates/test-programs/wasi-tests/src/bin/readlink.rs
+++ b/crates/test-programs/wasi-tests/src/bin/readlink.rs
@@ -1,5 +1,5 @@
 use std::{env, process};
-use wasi_tests::{create_file, open_scratch_directory};
+use wasi_tests::{assert_errno, create_file, open_scratch_directory};
 
 unsafe fn test_readlink(dir_fd: wasi::Fd) {
     // Create a file in the scratch directory.
@@ -25,11 +25,7 @@ unsafe fn test_readlink(dir_fd: wasi::Fd) {
     let err = wasi::path_readlink(dir_fd, "symlink", buf.as_mut_ptr(), buf.len())
         .err()
         .expect("readlink with too-small buffer should fail");
-    assert_eq!(
-        err.raw_error(),
-        wasi::ERRNO_RANGE,
-        "readlink with too-small buffer should give ERANGE"
-    );
+    assert_errno!(err.raw_error(), wasi::ERRNO_RANGE);
 
     // Clean up.
     wasi::path_unlink_file(dir_fd, "target").expect("removing a file");
diff --git a/crates/test-programs/wasi-tests/src/bin/remove_directory_trailing_slashes.rs b/crates/test-programs/wasi-tests/src/bin/remove_directory_trailing_slashes.rs
index 014d886d5b..1a5a1dd68a 100644
--- a/crates/test-programs/wasi-tests/src/bin/remove_directory_trailing_slashes.rs
+++ b/crates/test-programs/wasi-tests/src/bin/remove_directory_trailing_slashes.rs
@@ -1,5 +1,5 @@
 use std::{env, process};
-use wasi_tests::{create_file, open_scratch_directory};
+use wasi_tests::{assert_errno, create_file, open_scratch_directory};
 
 unsafe fn test_remove_directory_trailing_slashes(dir_fd: wasi::Fd) {
     // Create a directory in the scratch directory.
@@ -21,22 +21,20 @@ unsafe fn test_remove_directory_trailing_slashes(dir_fd: wasi::Fd) {
     create_file(dir_fd, "file");
 
     // Test that removing it with no trailing slash fails.
-    assert_eq!(
+    assert_errno!(
         wasi::path_remove_directory(dir_fd, "file")
             .expect_err("remove_directory without a trailing slash on a file should fail")
             .raw_error(),
         wasi::ERRNO_NOTDIR,
-        "errno should be ERRNO_NOTDIR"
     );
 
     // Test that removing it with a trailing slash fails.
     // XXX windows behavior here is NOENT instead of NOTDIR
-    assert_eq!(
+    assert_errno!(
         wasi::path_remove_directory(dir_fd, "file/")
             .expect_err("remove_directory with a trailing slash on a file should fail")
             .raw_error(),
         wasi::ERRNO_NOTDIR,
-        "errno should be ERRNO_NOTDIR"
     );
 
     wasi::path_unlink_file(dir_fd, "file").expect("removing a file");
diff --git a/crates/test-programs/wasi-tests/src/bin/remove_nonempty_directory.rs b/crates/test-programs/wasi-tests/src/bin/remove_nonempty_directory.rs
index daff21c2da..19488e748d 100644
--- a/crates/test-programs/wasi-tests/src/bin/remove_nonempty_directory.rs
+++ b/crates/test-programs/wasi-tests/src/bin/remove_nonempty_directory.rs
@@ -1,5 +1,5 @@
 use std::{env, process};
-use wasi_tests::open_scratch_directory;
+use wasi_tests::{assert_errno, open_scratch_directory};
 
 unsafe fn test_remove_nonempty_directory(dir_fd: wasi::Fd) {
     // Create a directory in the scratch directory.
@@ -9,12 +9,11 @@ unsafe fn test_remove_nonempty_directory(dir_fd: wasi::Fd) {
     wasi::path_create_directory(dir_fd, "dir/nested").expect("creating a subdirectory");
 
     // Test that attempting to unlink the first directory returns the expected error code.
-    assert_eq!(
+    assert_errno!(
         wasi::path_remove_directory(dir_fd, "dir")
             .expect_err("remove_directory on a directory should return ENOTEMPTY")
             .raw_error(),
-        wasi::ERRNO_NOTEMPTY,
-        "errno should be ERRNO_NOTEMPTY",
+        wasi::ERRNO_NOTEMPTY
     );
 
     // Removing the directories.
diff --git a/crates/test-programs/wasi-tests/src/bin/renumber.rs b/crates/test-programs/wasi-tests/src/bin/renumber.rs
index 9e411cdbd6..8f86f83cc5 100644
--- a/crates/test-programs/wasi-tests/src/bin/renumber.rs
+++ b/crates/test-programs/wasi-tests/src/bin/renumber.rs
@@ -1,6 +1,6 @@
 use more_asserts::assert_gt;
 use std::{env, process};
-use wasi_tests::open_scratch_directory;
+use wasi_tests::{assert_errno, open_scratch_directory};
 
 unsafe fn test_renumber(dir_fd: wasi::Fd) {
     let pre_fd: wasi::Fd = (libc::STDERR_FILENO + 1) as wasi::Fd;
@@ -49,12 +49,11 @@ unsafe fn test_renumber(dir_fd: wasi::Fd) {
     wasi::fd_renumber(fd_from, fd_to).expect("renumbering two descriptors");
 
     // Ensure that fd_from is closed
-    assert_eq!(
+    assert_errno!(
         wasi::fd_close(fd_from)
             .expect_err("closing already closed file descriptor")
             .raw_error(),
         wasi::ERRNO_BADF,
-        "errno should be ERRNO_BADF"
     );
 
     // Ensure that fd_to is still open.
diff --git a/crates/test-programs/wasi-tests/src/bin/symlink_filestat.rs b/crates/test-programs/wasi-tests/src/bin/symlink_filestat.rs
index 2d2cf9a0a6..c2b59221e2 100644
--- a/crates/test-programs/wasi-tests/src/bin/symlink_filestat.rs
+++ b/crates/test-programs/wasi-tests/src/bin/symlink_filestat.rs
@@ -3,7 +3,7 @@ use std::{env, process};
 use wasi_tests::open_scratch_directory;
 
 unsafe fn test_path_filestat(dir_fd: wasi::Fd) {
-    let mut fdstat = wasi::fd_fdstat_get(dir_fd).expect("fd_fdstat_get");
+    let fdstat = wasi::fd_fdstat_get(dir_fd).expect("fd_fdstat_get");
     assert_ne!(
         fdstat.fs_rights_base & wasi::RIGHTS_PATH_FILESTAT_GET,
         0,
diff --git a/crates/test-programs/wasi-tests/src/bin/symlink_loop.rs b/crates/test-programs/wasi-tests/src/bin/symlink_loop.rs
index 6422aad53a..28dd21a1e1 100644
--- a/crates/test-programs/wasi-tests/src/bin/symlink_loop.rs
+++ b/crates/test-programs/wasi-tests/src/bin/symlink_loop.rs
@@ -1,17 +1,16 @@
 use std::{env, process};
-use wasi_tests::open_scratch_directory;
+use wasi_tests::{assert_errno, open_scratch_directory};
 
 unsafe fn test_symlink_loop(dir_fd: wasi::Fd) {
     // Create a self-referencing symlink.
     wasi::path_symlink("symlink", dir_fd, "symlink").expect("creating a symlink");
 
     // Try to open it.
-    assert_eq!(
+    assert_errno!(
         wasi::path_open(dir_fd, 0, "symlink", 0, 0, 0, 0)
             .expect_err("opening a self-referencing symlink")
             .raw_error(),
         wasi::ERRNO_LOOP,
-        "errno should be ERRNO_LOOP",
     );
 
     // Clean up.
diff --git a/crates/test-programs/wasi-tests/src/bin/truncation_rights.rs b/crates/test-programs/wasi-tests/src/bin/truncation_rights.rs
index f846370728..13391d6a77 100644
--- a/crates/test-programs/wasi-tests/src/bin/truncation_rights.rs
+++ b/crates/test-programs/wasi-tests/src/bin/truncation_rights.rs
@@ -1,5 +1,5 @@
 use std::{env, process};
-use wasi_tests::{create_file, open_scratch_directory};
+use wasi_tests::{assert_errno, create_file, open_scratch_directory};
 
 unsafe fn test_truncation_rights(dir_fd: wasi::Fd) {
     // Create a file in the scratch directory.
@@ -64,12 +64,11 @@ unsafe fn test_truncation_rights(dir_fd: wasi::Fd) {
 
         // Test that we can't truncate the file without the
         // wasi_unstable::RIGHT_PATH_FILESTAT_SET_SIZE right.
-        assert_eq!(
+        assert_errno!(
             wasi::path_open(dir_fd, 0, "file", wasi::OFLAGS_TRUNC, 0, 0, 0)
                 .expect_err("truncating a file without path_filestat_set_size right")
                 .raw_error(),
             wasi::ERRNO_NOTCAPABLE,
-            "errno should be ERRNO_NOTCAPABLE",
         );
     }
 
diff --git a/crates/test-programs/wasi-tests/src/bin/unlink_file_trailing_slashes.rs b/crates/test-programs/wasi-tests/src/bin/unlink_file_trailing_slashes.rs
index 72b738cb7a..0079176cd6 100644
--- a/crates/test-programs/wasi-tests/src/bin/unlink_file_trailing_slashes.rs
+++ b/crates/test-programs/wasi-tests/src/bin/unlink_file_trailing_slashes.rs
@@ -1,5 +1,5 @@
 use std::{env, process};
-use wasi_tests::{create_file, open_scratch_directory};
+use wasi_tests::{assert_errno, create_file, open_scratch_directory};
 
 unsafe fn test_unlink_file_trailing_slashes(dir_fd: wasi::Fd) {
     // Create a directory in the scratch directory.
@@ -7,22 +7,20 @@ unsafe fn test_unlink_file_trailing_slashes(dir_fd: wasi::Fd) {
 
     // Test that unlinking it fails.
     // XXX windows errno here is ACCES
-    assert_eq!(
+    assert_errno!(
         wasi::path_unlink_file(dir_fd, "dir")
             .expect_err("unlink_file on a directory should fail")
             .raw_error(),
         wasi::ERRNO_ISDIR,
-        "errno should be ERRNO_ISDIR"
     );
 
     // Test that unlinking it with a trailing flash fails.
     // XXX windows errno here is ACCES
-    assert_eq!(
+    assert_errno!(
         wasi::path_unlink_file(dir_fd, "dir/")
             .expect_err("unlink_file on a directory should fail")
             .raw_error(),
         wasi::ERRNO_ISDIR,
-        "errno should be ERRNO_ISDIR"
     );
 
     // Clean up.
@@ -33,12 +31,11 @@ unsafe fn test_unlink_file_trailing_slashes(dir_fd: wasi::Fd) {
 
     // Test that unlinking it with a trailing flash fails.
     // XXX windows errno here is NOENT
-    assert_eq!(
+    assert_errno!(
         wasi::path_unlink_file(dir_fd, "file/")
             .expect_err("unlink_file with a trailing slash should fail")
             .raw_error(),
         wasi::ERRNO_NOTDIR,
-        "errno should be ERRNO_NOTDIR"
     );
 
     // Test that unlinking it with no trailing flash succeeds.