Add basic implementation of abandoning parent test

Just check that we have the correct number of processes

Fixes #44

test/test_e2e.py

@@ -0,0 +1,29 @@
+from __future__ import annotations
+import json
+from pathlib import Path
+import subprocess
+
+ABANDONING_PARENT = str(Path(__file__).with_name("data") / "abandoning_parent.sh")
+
+
+def test_sanity(temp_output_dir: str) -> None:
+    command = f"duct -p {temp_output_dir}log_ sleep 0.1"
+    subprocess.check_output(command, shell=True)
+
+
+def test_abandoning_parent(temp_output_dir: str) -> None:
+    duct_prefix = f"{temp_output_dir}log_"
+    num_children = 3
+    command = f"duct -p {duct_prefix} {ABANDONING_PARENT} {num_children} sleep 0.1"
+    subprocess.check_output(command, shell=True)
+
+    with open(f"{duct_prefix}usage.json") as usage_file:
+        all_samples = [json.loads(line) for line in usage_file]
+
+    max_processes_sample = {"processes": {}}
+    for sample in all_samples:
+        if len(max_processes_sample) < len(sample.get("processes")):
+            max_processes_sample = sample
+
+    # 1 for each child, 1 for pstree, 1 for parent
+    assert len(max_processes_sample) == num_children + 2