Add unit test for get_pretty_snapshot_diff(...).

invokeai/backend/model_management/memory_snapshot.py

@@ -65,10 +65,8 @@ class MemorySnapshot:
 def get_pretty_snapshot_diff(snapshot_1: MemorySnapshot, snapshot_2: MemorySnapshot) -> str:
     """Get a pretty string describing the difference between two `MemorySnapshot`s."""
 
-    def get_msg_line(prefix: str, val1: Optional[int], val2: Optional[int]):
+    def get_msg_line(prefix: str, val1: int, val2: int):
-        diff = None
+        diff = val2 - val1
-        if val1 is not None and val2 is not None:
-            diff = val2 - val1
         return f"{prefix: <30} ({(diff/GB):+5.3f}): {(val1/GB):5.3f}GB -> {(val2/GB):5.3f}GB\n"
 
     msg = ""
@@ -90,6 +88,7 @@ def get_pretty_snapshot_diff(snapshot_1: MemorySnapshot, snapshot_2: MemorySnaps
         libc_total_used_2 = snapshot_2.malloc_info.uordblks + snapshot_2.malloc_info.hblkhd
         msg += get_msg_line("libc total used", libc_total_used_1, libc_total_used_2)
 
-    msg += get_msg_line("VRAM", snapshot_1.vram, snapshot_2.vram)
+    if snapshot_1.vram is not None and snapshot_2.vram is not None:
+        msg += get_msg_line("VRAM", snapshot_1.vram, snapshot_2.vram)
 
     return msg

tests/backend/model_management/test_memory_snapshot.py

@@ -0,0 +1,35 @@
+import pytest
+
+from invokeai.backend.model_management.libc_util import Struct_mallinfo2
+from invokeai.backend.model_management.memory_snapshot import MemorySnapshot, get_pretty_snapshot_diff
+
+
+def test_memory_snapshot_capture():
+    """Smoke test of MemorySnapshot.capture()."""
+    snapshot = MemorySnapshot.capture()
+
+    # We just check process_ram, because it is the only field that should be supported on all platforms.
+    assert snapshot.process_ram > 0
+
+
+snapshots = [
+    MemorySnapshot(process_ram=1.0, vram=2.0, malloc_info=Struct_mallinfo2()),
+    MemorySnapshot(process_ram=1.0, vram=2.0, malloc_info=None),
+    MemorySnapshot(process_ram=1.0, vram=None, malloc_info=Struct_mallinfo2()),
+    MemorySnapshot(process_ram=1.0, vram=None, malloc_info=None),
+]
+
+
+@pytest.mark.parametrize("snapshot_1", snapshots)
+@pytest.mark.parametrize("snapshot_2", snapshots)
+def test_get_pretty_snapshot_diff(snapshot_1, snapshot_2):
+    """Test that get_pretty_snapshot_diff() works with various combinations of missing MemorySnapshot fields."""
+    msg = get_pretty_snapshot_diff(snapshot_1, snapshot_2)
+
+    expected_lines = 1
+    if snapshot_1.vram is not None and snapshot_2.vram is not None:
+        expected_lines += 1
+    if snapshot_1.malloc_info is not None and snapshot_2.malloc_info is not None:
+        expected_lines += 5
+
+    assert len(msg.splitlines()) == expected_lines