Correctly handling single string constraints (#670)

* correctly handling single string contraints

* formatted changes with black

* Switch to a more systemic fix | update tests

* including null values for in_range checks

Co-authored-by: Gonzalez Avilés, Ruben <ruben.gonzalez_aviles@baloise.com>

pandera/checks.py

@@ -51,9 +51,7 @@ def _wrapper(cls, *args, **kwargs):
             args_dict = {**dict(zip(arg_names, args)), **kwargs}
             check = class_method(cls, *args, **kwargs)
             check.statistics = {
-                stat: args_dict.get(stat)
-                for stat in statistics_args
-                if args_dict.get(stat) is not None
+                stat: args_dict.get(stat) for stat in statistics_args
             }
             check.statistics_args = statistics_args
             return check

tests/io/test_io.py

@@ -126,6 +126,8 @@ def _create_schema(index="single"):
       in_range:
         min_value: 0
         max_value: 10
+        include_min: null
+        include_max: null
     unique: false
     coerce: false
     required: true
@@ -139,6 +141,8 @@ def _create_schema(index="single"):
       in_range:
         min_value: -10
         max_value: 20
+        include_min: null
+        include_max: null
     unique: false
     coerce: false
     required: true
@@ -763,6 +767,8 @@ def datetime_check(pandas_obj, *, stat):
       in_range:
         min_value: 10
         max_value: 99
+        include_min: null
+        include_max: null
     unique: true
     coerce: true
     required: true
@@ -800,7 +806,9 @@ def datetime_check(pandas_obj, *, stat):
     dtype: {STR_DTYPE}
     nullable: true
     checks:
-      str_length: 3
+      str_length:
+        min_value: 3
+        max_value: null
     unique: false
     coerce: true
     required: true
@@ -809,7 +817,9 @@ def datetime_check(pandas_obj, *, stat):
     dtype: {STR_DTYPE}
     nullable: true
     checks:
-      str_length: 3
+      str_length:
+        min_value: null
+        max_value: 3
     unique: false
     coerce: true
     required: true