Added SysCommand() tests

tests/syscalls/test_syscommand.py

@@ -0,0 +1,18 @@
+import pytest
+
+def test_SysCommand():
+	import archinstall
+	import subprocess
+
+	if not archinstall.SysCommand('whoami').decode().strip() == subprocess.check_output('whoami').decode().strip():
+		raise AssertionError(f"SysCommand('whoami') did not return expected output: {subprocess.check_output('whoami').decode()}")
+
+	try:
+		archinstall.SysCommand('nonexistingbinary-for-testing').decode().strip()
+	except archinstall.RequirementError:
+		pass # we want to make sure it fails with an exception unique to missing binary
+
+	try:
+		archinstall.SysCommand('ls -veryfaultyparameter').decode().strip()
+	except archinstall.SysCallError:
+		pass # We want it to raise a syscall error when a binary dislikes us