diff --git a/tests/run_tests.py b/tests/run_tests.py
new file mode 100644
index 0000000..a73d16e
--- /dev/null
+++ b/tests/run_tests.py
@@ -0,0 +1,127 @@
+import argparse
+import datetime
+import difflib
+import subprocess
+import sys
+import tempfile
+from pathlib import Path
+
+parser = argparse.ArgumentParser(description="Process some integers.")
+parser.add_argument("src", default="src", type=Path, help="src directory", nargs="?")
+parser.add_argument(
+    "tests", default="tests", type=Path, help="tests directory", nargs="?"
+)
+args = parser.parse_args()
+
+
+def make_log_file():
+    time = datetime.datetime.now().strftime("%Y-%m-%d_%H-%M-%S")
+    return (args.tests / time).with_suffix(".log")
+
+
+def log_new_test(in_path):
+    global LOG_FILE
+    with open(LOG_FILE, "a") as f:
+        f.write("# ======================================\n")
+        f.write(f"# Test: {in_path}\n")
+        f.write("# ======================================\n")
+
+
+def log_message(message):
+    global LOG_FILE
+    with open(LOG_FILE, "a") as f:
+        f.write(message)
+        f.write("\n")
+
+
+def log_return(ret):
+    if ret[0]:
+        log_message("Passed")
+    else:
+        log_message(f"Error: {ret[1]}")
+
+    log_message("# ======================================\n")
+    return ret
+
+
+def attempt_decode(out):
+    try:
+        return out.decode("utf-8")
+    except UnicodeDecodeError:
+        return "Invalid utf-8 in output"
+
+
+def diff_files(file1, file2):
+    with open(file1, "r") as f1, open(file2, "r") as f2:
+        diff = difflib.unified_diff(
+            f1.readlines(),
+            f2.readlines(),
+            fromfile=str(file1),
+            tofile=str(file2),
+        )
+        return "".join(diff)
+
+
+def run_test(exe_path, in_path):
+    expected_file = in_path.with_suffix(".out")
+    log_new_test(in_path)
+
+    with tempfile.TemporaryDirectory() as tmp:
+        temp = Path(tmp)
+        out_path = temp / "output"
+
+        test = subprocess.Popen(
+            [sys.executable, str(exe_path), str(in_path), "--out", str(out_path)],
+            stdout=subprocess.DEVNULL,
+            stderr=subprocess.PIPE,
+        )
+
+        try:
+            _, stderr = test.communicate(1)
+        except subprocess.TimeoutExpired:
+            return [False, "Timed out"]
+
+        if test.returncode != 0:
+            log_message(attempt_decode(stderr))
+            return log_return(
+                [
+                    False,
+                    f"Expected returncode 0 got: {test.returncode}",
+                ]
+            )
+
+        diff = diff_files(expected_file, out_path)
+
+        if diff != "":
+            log_message(diff)
+            return log_return([False, "Output did not match"])
+
+    return log_return([True])
+
+
+if __name__ == "__main__":
+    LOG_FILE = make_log_file()
+    PASS_MESSAGE = "✅ Passed"
+    ERROR_MESSAGE = "❌ Error:"
+
+    tests = list(Path(args.tests).glob("**/*.in"))
+    max_len = max(len(str(t)) for t in tests)
+
+    for test in tests:
+        print(f"{test}...", end="")
+        res = run_test(args.src / "main.py", test)
+
+        if res[0]:
+            dots = 80 - len(str(test)) - 3 - len(PASS_MESSAGE)
+
+            if dots > 0:
+                print("." * dots, end="")
+            print(PASS_MESSAGE)
+        else:
+            dots = 80 - len(str(test)) - 3 - len(ERROR_MESSAGE) - len(res[1])
+
+            if dots > 0:
+                print("." * dots, end="")
+            print(f"{ERROR_MESSAGE} {res[1]}")
+
+    print(f"Log file at: {LOG_FILE}")