From 9d32489993177b3584676b6715192252872123e3 Mon Sep 17 00:00:00 2001
From: Eric <eric@dgren.dev>
Date: Wed, 4 Mar 2026 03:19:28 +0000
Subject: [PATCH] feat: add phase 4 bun_test bootstrap

---
 README.md                           |  6 +++
 bun/defs.bzl                        |  2 +
 internal/bun_test.bzl               | 59 ++++++++++++++++++++++++++++-
 tests/bun_test_test/BUILD.bazel     | 19 ++++++++++
 tests/bun_test_test/failing.test.ts |  5 +++
 tests/bun_test_test/passing.test.ts |  5 +++
 6 files changed, 94 insertions(+), 2 deletions(-)
 create mode 100644 tests/bun_test_test/BUILD.bazel
 create mode 100644 tests/bun_test_test/failing.test.ts
 create mode 100644 tests/bun_test_test/passing.test.ts

diff --git a/README.md b/README.md
index 67d7abf..e81d03f 100644
--- a/README.md
+++ b/README.md
@@ -22,3 +22,9 @@ Phase 3 bootstrap is in place:
 - Executable `bun_binary` rule (`/internal/bun_binary.bzl`)
 - Public export via `bun/defs.bzl`
 - Focused JS/TS runnable tests (`//tests/binary_test:all`)
+
+Phase 4 bootstrap is in place:
+
+- Test rule `bun_test` (`/internal/bun_test.bzl`)
+- Public export via `bun/defs.bzl`
+- Focused passing/failing test targets (`//tests/bun_test_test:all`)
diff --git a/bun/defs.bzl b/bun/defs.bzl
index 48cd3f7..0664176 100644
--- a/bun/defs.bzl
+++ b/bun/defs.bzl
@@ -1,5 +1,6 @@
 load("//internal:bun_binary.bzl", "bun_binary")
 load("//internal:bun_install.bzl", "bun_install")
+load("//internal:bun_test.bzl", "bun_test")
 load(":repositories.bzl", "bun_register_toolchains", "bun_repositories")
 load(":toolchain.bzl", "BunToolchainInfo", "bun_toolchain")
 
@@ -7,6 +8,7 @@ __all__ = [
     "BunToolchainInfo",
     "bun_binary",
     "bun_install",
+    "bun_test",
     "bun_register_toolchains",
     "bun_repositories",
     "bun_toolchain",
diff --git a/internal/bun_test.bzl b/internal/bun_test.bzl
index f013b9e..6f4a5a4 100644
--- a/internal/bun_test.bzl
+++ b/internal/bun_test.bzl
@@ -1,2 +1,57 @@
-def bun_test(**_kwargs):
-    fail("bun_test is not implemented yet")
+"""Rule for running test suites with Bun."""
+
+
+def _bun_test_impl(ctx):
+    toolchain = ctx.toolchains["//bun:toolchain_type"]
+    bun_bin = toolchain.bun.bun_bin
+
+    src_args = " ".join(["\"{}\"".format(src.path) for src in ctx.files.srcs])
+    launcher = ctx.actions.declare_file(ctx.label.name)
+    ctx.actions.write(
+        output = launcher,
+        is_executable = True,
+        content = """#!/usr/bin/env bash
+set -euo pipefail
+
+extra_args=()
+if [[ -n "${{TESTBRIDGE_TEST_ONLY:-}}" ]]; then
+  extra_args+=("--test-name-pattern" "${{TESTBRIDGE_TEST_ONLY}}")
+fi
+if [[ -n "${{COVERAGE_DIR:-}}" ]]; then
+  extra_args+=("--coverage")
+fi
+
+exec "{}" test {} "${{extra_args[@]}}" "$@"
+""".format(bun_bin.path, src_args),
+    )
+
+    transitive_files = []
+    if ctx.attr.node_modules:
+        transitive_files.append(ctx.attr.node_modules[DefaultInfo].files)
+
+    runfiles = ctx.runfiles(
+        files = [bun_bin] + ctx.files.srcs + ctx.files.data,
+        transitive_files = depset(transitive = transitive_files),
+    )
+
+    return [
+        DefaultInfo(
+            executable = launcher,
+            runfiles = runfiles,
+        ),
+    ]
+
+
+bun_test = rule(
+    implementation = _bun_test_impl,
+    attrs = {
+        "srcs": attr.label_list(
+            mandatory = True,
+            allow_files = [".js", ".ts", ".jsx", ".tsx", ".mjs", ".cjs"],
+        ),
+        "node_modules": attr.label(),
+        "data": attr.label_list(allow_files = True),
+    },
+    test = True,
+    toolchains = ["//bun:toolchain_type"],
+)
diff --git a/tests/bun_test_test/BUILD.bazel b/tests/bun_test_test/BUILD.bazel
new file mode 100644
index 0000000..9b27da4
--- /dev/null
+++ b/tests/bun_test_test/BUILD.bazel
@@ -0,0 +1,19 @@
+load("//bun:defs.bzl", "bun_test")
+
+bun_test(
+    name = "passing_suite",
+    srcs = ["passing.test.ts"],
+    target_compatible_with = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:linux",
+    ],
+)
+
+bun_test(
+    name = "failing_suite",
+    srcs = ["failing.test.ts"],
+    target_compatible_with = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:linux",
+    ],
+)
diff --git a/tests/bun_test_test/failing.test.ts b/tests/bun_test_test/failing.test.ts
new file mode 100644
index 0000000..cb462d0
--- /dev/null
+++ b/tests/bun_test_test/failing.test.ts
@@ -0,0 +1,5 @@
+import { expect, test } from "bun:test";
+
+test("failing suite", () => {
+  expect(1 + 1).toBe(3);
+});
diff --git a/tests/bun_test_test/passing.test.ts b/tests/bun_test_test/passing.test.ts
new file mode 100644
index 0000000..b5e066a
--- /dev/null
+++ b/tests/bun_test_test/passing.test.ts
@@ -0,0 +1,5 @@
+import { expect, test } from "bun:test";
+
+test("passing suite", () => {
+  expect(1 + 1).toBe(2);
+});