1 files changed, 142 insertions, 0 deletions
diff --git a/tests/functional/u/use/use_implicit_booleaness_not_comparison.py b/tests/functional/u/use/use_implicit_booleaness_not_comparison.py
new file mode 100644
index 000000000..18ca9c370
--- /dev/null
+++ b/tests/functional/u/use/use_implicit_booleaness_not_comparison.py
@@ -0,0 +1,142 @@
+# pylint: disable=missing-docstring, missing-module-docstring, invalid-name
+# pylint: disable=too-few-public-methods, line-too-long, dangerous-default-value
+# https://github.com/PyCQA/pylint/issues/4774
+
+def github_issue_4774():
+    # Test literals
+    # https://github.com/PyCQA/pylint/issues/4774
+    good_list = []
+    if not good_list:
+        pass
+
+    bad_list = []
+    if bad_list == []: # [use-implicit-booleaness-not-comparison]
+        pass
+
+# Testing for empty literals
+empty_tuple = ()
+empty_list = []
+empty_dict = {}
+
+if empty_tuple == (): # [use-implicit-booleaness-not-comparison]
+    pass
+
+if empty_list == []: # [use-implicit-booleaness-not-comparison]
+    pass
+
+if empty_dict == {}: # [use-implicit-booleaness-not-comparison]
+    pass
+
+if () == empty_tuple: # [use-implicit-booleaness-not-comparison]
+    pass
+
+if [] == empty_list: # [use-implicit-booleaness-not-comparison]
+    pass
+
+if {} == empty_dict: # [use-implicit-booleaness-not-comparison]
+    pass
+
+def bad_tuple_return():
+    t = (1, )
+    return t == () # [use-implicit-booleaness-not-comparison]
+
+def bad_list_return():
+    b = [1]
+    return b == [] # [use-implicit-booleaness-not-comparison]
+
+def bad_dict_return():
+    c = {1: 1}
+    return c == {} # [use-implicit-booleaness-not-comparison]
+
+assert () == empty_tuple # [use-implicit-booleaness-not-comparison]
+assert [] == empty_list # [use-implicit-booleaness-not-comparison]
+assert {} != empty_dict # [use-implicit-booleaness-not-comparison]
+assert () < empty_tuple # [use-implicit-booleaness-not-comparison]
+assert [] <= empty_list # [use-implicit-booleaness-not-comparison]
+assert () > empty_tuple # [use-implicit-booleaness-not-comparison]
+assert [] >= empty_list # [use-implicit-booleaness-not-comparison]
+
+assert [] == []
+assert {} != {}
+assert () == ()
+
+d = {}
+
+if d in {}:
+    pass
+
+class NoBool:
+    def __init__(self):
+        self.a = 2
+
+class YesBool:
+    def __init__(self):
+        self.a = True
+
+    def __bool__(self):
+        return self.a
+
+
+# Should be triggered
+a = NoBool()
+if [] == a: # [use-implicit-booleaness-not-comparison]
+    pass
+
+a = YesBool()
+if a == []:
+    pass
+
+# compound test cases
+
+e = []
+f = {}
+
+if e == [] and f == {}: # [use-implicit-booleaness-not-comparison, use-implicit-booleaness-not-comparison]
+    pass
+
+
+named_fields = [0, "", "42", "forty two"]
+empty = any(field == "" for field in named_fields)
+
+something_else = NoBool()
+empty_literals = [[], {}, ()]
+is_empty = any(field == something_else for field in empty_literals)
+
+# this should work, but it doesn't since, input parameter only get the latest one, not all when inferred()
+h, i, j = 1, None, [1,2,3]
+
+def test(k):
+    print(k == {})
+
+def test_with_default(k={}):
+    print(k == {}) # [use-implicit-booleaness-not-comparison]
+    print(k == 1)
+
+test(h)
+test(i)
+test(j)
+
+test_with_default(h)
+test_with_default(i)
+test_with_default(j)
+
+# pylint: disable=import-outside-toplevel, wrong-import-position, import-error
+# Numpy has its own implementation of __bool__, but base class has list, that's why the comparison check is happening
+import numpy
+numpy_array = numpy.array([0])
+if numpy_array == []: # [use-implicit-booleaness-not-comparison]
+    print('numpy_array')
+if numpy_array != []: # [use-implicit-booleaness-not-comparison]
+    print('numpy_array')
+if numpy_array >= (): # [use-implicit-booleaness-not-comparison]
+    print('b')
+
+# pandas has its own implementations of __bool__ and is not subclass of list, dict, or tuple; that's why comparison check is not happening
+import pandas as pd
+pandas_df = pd.DataFrame()
+if pandas_df == []:
+    pass
+if pandas_df != ():
+    pass
+if pandas_df <= []:
+    print("truth value of a dataframe is ambiguous")