diff --git a/e2e/binary/sum/BUILD.bazel b/e2e/binary/sum/BUILD.bazel
index 60c1d1fa86b7cc85fa071a2dbf0d9de661e82aaf..cf42fdaed1672303d5f19208b050a63e4c2e0017 100644
--- a/e2e/binary/sum/BUILD.bazel
+++ b/e2e/binary/sum/BUILD.bazel
@@ -1,11 +1,30 @@
-load("@bazel_skylib//rules:build_test.bzl", "build_test")
+load("@rules_python_pytest//python_pytest:defs.bzl", "py_pytest_test")
+load("@bazel_skylib//rules:native_binary.bzl", "native_test")
 
-# TODO: write an _actual_ test for `sum`
+py_pytest_test(
+    name = "pytest",
+    size = "small",
+    srcs = ["sum.py"],
+    data = [
+        "@ape//ape:sum",
+    ],
+    deps = [
+        "//binary:pytest",
+    ],
+)
 
-build_test(
-    name = "sum",
+native_test(
+    name = "version",
     size = "small",
-    tags = ["stub"],
-    targets = ["@ape//ape:sum"],
+    src = "@ape//ape:sum",
+    args = ["--version"],
+)
+
+test_suite(
+    name = "sum",
+    tests = [
+        "pytest",
+        "version",
+    ],
     visibility = ["//:__subpackages__"],
 )
diff --git a/e2e/binary/sum/sum.py b/e2e/binary/sum/sum.py
new file mode 100644
index 0000000000000000000000000000000000000000..9264550b6282460a00028a868124ba47c7acb8b3
--- /dev/null
+++ b/e2e/binary/sum/sum.py
@@ -0,0 +1,21 @@
+from __future__ import annotations
+
+from subprocess import run
+from pathlib import Path
+
+from binary.tool import Tool
+
+
+def test_sum(tool: Tool, tmp_path: Path) -> None:
+    binary = tool("sum")
+    input_path = tmp_path / "input_file"
+
+    with open(input_path, "w") as file:
+        file.write("hello")
+    cmd = (binary, input_path)
+    result = run(cmd, check=True, timeout=30, capture_output=True, text=True)
+
+    # Remove path from output
+    actual = result.stdout.rsplit(" ", 1)[0]
+    expected = "08403     1"
+    assert actual == expected