Updated test and added more comments

Author: seanlaw

tests/test_cache.py

@@ -16,9 +16,9 @@ def test_cache_save_after_clear():
     cache_dir = "stumpy/__pycache__"
 
     cache.clear(cache_dir)
-    cache.save()  # Saves nbi files only until njit funcs are called for the first time
+    stump(T, m)
+    cache.save()  # Enable and save both `.nbi` and `.nbc` cache files
 
-    stump(T, m)  # Saves nbc files, subsequent saves will write both nbi and nbc files
     ref_cache = cache._get_cache(cache_dir)
 
     if numba.config.DISABLE_JIT:
@@ -28,7 +28,9 @@ def test_cache_save_after_clear():
 
     cache.clear(cache_dir)
     assert len(cache._get_cache(cache_dir)) == 0
-    cache.save()  # Save both nbi and nbc files without needing to call `stump` function
+    # Note that `stump(T, m)` has already been called once above and any subsequent
+    # calls to `cache.save()` will automatically save both `.nbi` and `.nbc` cache files
+    cache.save()  # Save both `.nbi` and `.nbc` cache files
 
     comp_cache = cache._get_cache(cache_dir)