feat: add a histrical wit-bindgen

__wasm/wit-bindgen-sample/wit-bindgen/crates/wit-component/tests/interfaces.rs

@@ -0,0 +1,60 @@
+use anyhow::{Context, Result};
+use pretty_assertions::assert_eq;
+use std::fs;
+use wit_component::InterfaceEncoder;
+use wit_parser::Interface;
+
+/// Tests the encoding of individual interface files.
+///
+/// This test looks in the `interfaces/` directory for test cases.
+///
+/// Each test case is a directory containing a `<testcase>.wit` file
+/// and an expected `<testcase>.wat` file.
+///
+/// The test encodes the wit file, prints the resulting component, and
+/// compares the output to the wat file.
+///
+/// Run the test with the environment variable `BLESS` set to update
+/// the wat baseline file.
+#[test]
+fn interface_encoding() -> Result<()> {
+    for entry in fs::read_dir("tests/interfaces")? {
+        let path = entry?.path();
+        if !path.is_dir() {
+            continue;
+        }
+
+        let test_case = path.file_stem().unwrap().to_str().unwrap();
+        let wit_path = path.join(test_case).with_extension("wit");
+
+        let interface = Interface::parse_file(&wit_path)?;
+
+        let encoder = InterfaceEncoder::new(&interface).validate(true);
+
+        let bytes = encoder.encode().with_context(|| {
+            format!(
+                "failed to encode a component from interface `{}` for test case `{}`",
+                wit_path.display(),
+                test_case,
+            )
+        })?;
+
+        let output = wasmprinter::print_bytes(&bytes)?;
+        let wat_path = wit_path.with_extension("wat");
+
+        if std::env::var_os("BLESS").is_some() {
+            fs::write(&wat_path, output)?;
+        } else {
+            assert_eq!(
+                fs::read_to_string(&wat_path)?.replace("\r\n", "\n"),
+                output,
+                "encoding of wit file `{}` did not match the expected wat file `{}` for test case `{}`",
+                wit_path.display(),
+                wat_path.display(),
+                test_case
+            );
+        }
+    }
+
+    Ok(())
+}