test MaskGroup serialization is invertible #172

tests/test_data.py

@@ -9,6 +9,7 @@
 import dataclasses as dc
 import math
 import random
+import string
 
 import numpy as np
 import pytest
@@ -18,6 +19,13 @@
 ZERO_TOL = 1.0e-10  # absolute tolerance for detecting zero-values
 
 
+def random_alphanum(length: int) -> str:
+    return "".join(
+        random.choice(string.ascii_letters + string.digits)
+        for _ in range(length)
+    )
+
+
 @dc.dataclass
 class MomentumExample:
     """Dataclass for representing the four-momentum of a particle, based
@@ -111,3 +119,57 @@ def test_pmu_zero_pt() -> None:
     with pytest.warns(gcl.base.NumericalStabilityWarning):
         phi_invalid = math.isnan(pmu_zero_pt.phi.item())
     assert phi_invalid, "Azimuth is not NaN when pT is low"
+
+
+def generate_tree(
+    max_width: int, max_depth: int, leaf_length: int
+) -> gcl.MaskGroup:
+    """Generates a nested MaskGroup tree structure, with random branch
+    widths and depths.
+
+    Parameters
+    ----------
+    max_width, max_depth : int
+        Maximum limits on the nested tree structure.
+    leaf_length : int
+        The number of elements in the leaf MaskArrays.
+
+    Returns
+    -------
+    MaskGroup
+        Tree structure, with random structure, and random MaskArrays at
+        the leaf levels.
+    """
+    rng = np.random.default_rng()
+
+    def generate_branch(depth: int) -> gcl.base.MaskBase:
+        if (depth == 0) or (
+            random.choice((True, False)) and not (depth == max_depth)
+        ):
+            return gcl.MaskArray(
+                rng.integers(0, 2, size=leaf_length, dtype=np.bool_)
+            )
+        num_children = random.randint(1, max_width)
+        return gcl.MaskGroup(
+            {
+                random_alphanum(10): generate_branch(depth - 1)
+                for _ in range(num_children)
+            }
+        )
+
+    return generate_branch(max_depth)
+
+
+def test_maskgroup_serialize_inverse() -> None:
+    """Tests that instantiating a MaskGroup from its serialization
+    yields identical results to the original.
+    """
+    invertible = True
+    for _ in range(10):
+        maskgroup = generate_tree(
+            max_width=5,
+            max_depth=10,
+            leaf_length=random.randint(0, 1_000),
+        )
+        invertible &= maskgroup.equal_to(gcl.MaskGroup(maskgroup.serialize()))
+    assert invertible, "Serializing MaskGroups is not invertible."