fix: awkward_form breadcrumbs class issue 880 (#886)

* fix: awkward_form breadcrumbs class issue 879

* Add local file for testing before using scikit-hep-testdata.

* style: pre-commit fixes

* Fix test imports.

* Get test data from skhep_testdata.

* Make a copy of the breadcrumbs before changing them.

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

src/uproot/behaviors/TBranch.py

@@ -2490,7 +2490,7 @@ def _awkward_check(self, interpretation):
 
     {}
 
-instead, try library="np" instead of library="ak" or globally set uproot.default_library
+instead, try library="np" rather than library="ak" or globally set uproot.default_library
 
 in file {}
 in object {}""".format(

src/uproot/models/TAtt.py

@@ -526,6 +526,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -679,6 +680,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:

src/uproot/models/TGraph.py

@@ -249,6 +249,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -455,6 +456,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -666,6 +668,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:

src/uproot/models/TH.py

@@ -338,6 +338,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -814,6 +815,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -1119,6 +1121,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -1328,6 +1331,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -1517,6 +1521,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -1679,6 +1684,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -1836,6 +1842,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -1993,6 +2000,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -2155,6 +2163,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -2317,6 +2326,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -2480,6 +2490,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -2638,6 +2649,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -2801,6 +2813,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -2964,6 +2977,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -3127,6 +3141,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -3291,6 +3306,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -3450,6 +3466,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -3614,6 +3631,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -3778,6 +3796,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -3978,6 +3997,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -4217,6 +4237,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:
@@ -4458,6 +4479,7 @@ def awkward_form(cls, file, context):
             raise uproot.interpretation.objects.CannotBeAwkward(
                 "classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded"
             )
+        context = context.copy()
         context["breadcrumbs"] = context["breadcrumbs"] + (cls,)
         contents = {}
         if context["header"]:

src/uproot/streamers.py

@@ -242,6 +242,7 @@ def class_code(self):
             "        from awkward.forms import NumpyForm, ListOffsetForm, RegularForm, RecordForm",
             "        if cls in context['breadcrumbs']:",
             "            raise uproot.interpretation.objects.CannotBeAwkward('classes that can contain members of the same type cannot be Awkward Arrays because the depth of instances is unbounded')",
+            "        context = context.copy()",
             "        context['breadcrumbs'] = context['breadcrumbs'] + (cls,)",
             "        contents = {}",
             "        if context['header']:",

tests/test_0886-fix-awkward-form-breadcrumbs.py

@@ -0,0 +1,10 @@
+# BSD 3-Clause License; see https://github.com/scikit-hep/uproot5/blob/main/LICENSE
+
+import uproot
+import skhep_testdata
+
+
+def test_fix_awkward_form_breadcrumbs():
+    file = uproot.open(skhep_testdata.data_path("uproot-issue-880.root"))
+    tree = file["Z"]
+    assert tree.num_entries == 116