1 files changed, 95 insertions, 0 deletions
diff --git a/tools/wasi-headers/tests/verify.rs b/tools/wasi-headers/tests/verify.rs
new file mode 100644
index 0000000..faae763
--- /dev/null
+++ b/tools/wasi-headers/tests/verify.rs
@@ -0,0 +1,95 @@
+use std::fs;
+use std::path::Path;
+
+#[test]
+fn assert_same_as_src() {
+    let actual_header =
+        fs::read_to_string(wasi_headers::libc_wasi_api_header()).expect("read libc wasi/api.h");
+    let actual_source =
+        fs::read_to_string(wasi_headers::libc_wasi_api_source()).expect("read libc wasi/api.h");
+    let witx_files = wasi_headers::snapshot_witx_files().expect("parse snapshot witx files");
+    let expected = wasi_headers::generate(&witx_files).expect("header generation");
+    if actual_header == expected.header && actual_source == expected.source {
+        return;
+    }
+
+    if actual_header != expected.header {
+        diff(
+            &wasi_headers::libc_wasi_api_header(),
+            &actual_header,
+            &expected.header,
+        );
+    }
+    if actual_header != expected.header {
+        diff(
+            &wasi_headers::libc_wasi_api_source(),
+            &actual_header,
+            &expected.header,
+        );
+    }
+}
+
+fn diff(path: &Path, actual: &str, expected: &str) {
+    eprintln!("The following diff was found between the generated copy and the");
+    eprintln!("source copy of {:?} in the tree:", path);
+    eprintln!();
+
+    let mut expected_line = 1;
+    let mut actual_line = 1;
+    let mut separated = false;
+    let mut any_lines = false;
+    for diff in diff::lines(&expected, &actual) {
+        match diff {
+            diff::Result::Left(l) => {
+                eprintln!("line {}: -{}", expected_line, l);
+                expected_line += 1;
+                separated = false;
+                any_lines = true;
+            }
+            diff::Result::Both(_, _) => {
+                expected_line += 1;
+                actual_line += 1;
+                if !separated {
+                    eprintln!("...");
+                    separated = true;
+                }
+            }
+            diff::Result::Right(r) => {
+                eprintln!("line {}: +{}", actual_line, r);
+                actual_line += 1;
+                separated = false;
+                any_lines = true;
+            }
+        }
+    }
+
+    if !any_lines {
+        eprintln!();
+        eprintln!(
+            "Somehow there was a diff with no lines differing. Lengths: {} and {}.",
+            expected.len(),
+            actual.len()
+        );
+        for (index, (a, b)) in actual.chars().zip(expected.chars()).enumerate() {
+            if a != b {
+                eprintln!("char difference at index {}: '{}' != '{}'", index, a, b);
+            }
+        }
+        for (index, (a, b)) in actual.bytes().zip(expected.bytes()).enumerate() {
+            if a != b {
+                eprintln!("byte difference at index {}: b'{}' != b'{}'", index, a, b);
+            }
+        }
+        eprintln!();
+        eprintln!("actual: {}", actual);
+        eprintln!();
+        eprintln!("expected: {}", expected);
+    }
+
+    eprintln!();
+    eprintln!(
+        "To regenerate the files, run `cd tools/wasi-headers && cargo run -- generate-libc`."
+    );
+    eprintln!();
+    panic!();
+}