From bea2f9ae6fcc2209b4365bafea5b3c60762286ea Mon Sep 17 00:00:00 2001
From: daxpedda <daxpedda@gmail.com>
Date: Tue, 10 Dec 2024 09:50:45 +0100
Subject: [PATCH] Add test coverage support for Node.js

---
 CHANGELOG.md                                      |  3 +++
 .../cli/src/bin/wasm-bindgen-test-runner/main.rs  |  2 +-
 .../cli/src/bin/wasm-bindgen-test-runner/node.rs  | 15 ++++++++++++++-
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 95b8f96cbfa..b0cc02f21a0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,9 @@
 * Add a `copy_to_uninit()` method to all `TypedArray`s. It takes `&mut [MaybeUninit<T>]` and returns `&mut [T]`.
   [#4340](https://github.com/rustwasm/wasm-bindgen/pull/4340)
 
+* Add test coverage support for Node.js.
+  [#4348](https://github.com/rustwasm/wasm-bindgen/pull/4348)
+
 ### Changed
 
 * Optional parameters are now typed as `T | undefined | null` to reflect the actual JS behavior.
diff --git a/crates/cli/src/bin/wasm-bindgen-test-runner/main.rs b/crates/cli/src/bin/wasm-bindgen-test-runner/main.rs
index 76259378054..b1ebea28c1e 100644
--- a/crates/cli/src/bin/wasm-bindgen-test-runner/main.rs
+++ b/crates/cli/src/bin/wasm-bindgen-test-runner/main.rs
@@ -271,7 +271,7 @@ fn main() -> anyhow::Result<()> {
 
     match test_mode {
         TestMode::Node { no_modules } => {
-            node::execute(module, &tmpdir, &args, &tests, !no_modules)?
+            node::execute(module, &tmpdir, &args, &tests, !no_modules, coverage)?
         }
         TestMode::Deno => deno::execute(module, &tmpdir, &args, &tests)?,
         TestMode::Browser { .. }
diff --git a/crates/cli/src/bin/wasm-bindgen-test-runner/node.rs b/crates/cli/src/bin/wasm-bindgen-test-runner/node.rs
index ba131cf5465..3ac475fcb3e 100644
--- a/crates/cli/src/bin/wasm-bindgen-test-runner/node.rs
+++ b/crates/cli/src/bin/wasm-bindgen-test-runner/node.rs
@@ -1,7 +1,7 @@
 use std::env;
 use std::ffi::OsString;
 use std::fs;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 use std::process::Command;
 
 use anyhow::{Context, Error};
@@ -44,10 +44,12 @@ pub fn execute(
     args: &[OsString],
     tests: &[String],
     module_format: bool,
+    coverage: PathBuf,
 ) -> Result<(), Error> {
     let mut js_to_execute = format!(
         r#"
         {exit};
+        {fs};
         {wasm};
 
         {console_override}
@@ -62,6 +64,11 @@ pub fn execute(
             cx.args(process.argv.slice(2));
 
             const ok = await cx.run(tests.map(n => wasm.__wasm[n]));
+
+            const coverage = wasm.__wbgtest_cov_dump();
+            if (coverage !== undefined)
+                await fs.writeFile('{coverage}', coverage);
+
             if (!ok)
                 exit(1);
         }}
@@ -78,6 +85,12 @@ pub fn execute(
         } else {
             r"import { exit } from 'node:process'".to_string()
         },
+        fs = if !module_format {
+            r"const fs = require('node:fs/promises')".to_string()
+        } else {
+            r"import fs from 'node:fs/promises'".to_string()
+        },
+        coverage = coverage.display(),
         console_override = SHARED_SETUP,
     );