Add validation tests for OS, get_main_dir, timestamp, timestamp_as_sec helper functions

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

test/validation/items/common/helper_lib.py

@@ -0,0 +1,29 @@
+import libs.testium as libtm
+
+
+def check_os(expected_os):
+    result = libtm.OS()
+    assert result == expected_os, f"Expected {expected_os!r}, got {result!r}"
+    return 0
+
+
+def check_get_main_dir():
+    d = libtm.get_main_dir()
+    assert isinstance(d, str) and len(d) > 0
+    return 0
+
+
+def check_timestamp_as_sec_conversion():
+    assert libtm.timestamp_as_sec(0) == 0.0
+    assert libtm.timestamp_as_sec(10000) == 1.0
+    assert libtm.timestamp_as_sec(5000) == 0.5
+    return 0
+
+
+def check_timestamp():
+    libtm.init_timestamp()
+    t = libtm.timestamp()
+    assert isinstance(t, int) and t >= 0
+    ts = libtm.timestamp_as_sec()
+    assert isinstance(ts, float) and ts >= 0.0
+    return 0