Possible null reference assignment.

Public method 'Single_element_in_list_of_elements_in_a_structure' on test class 'LazyColumnEnumeratorTest' should be marked as a Fact. Reduce the visibility of the method, or add a Fact attribute to the method. (https://xunit.net/xunit.analyzers/rules/xUnit1013)

Public method 'List_of_one_element' on test class 'LazyColumnEnumeratorTest' should be marked as a Fact. Reduce the visibility of the method, or add a Fact attribute to the method. (https://xunit.net/xunit.analyzers/rules/xUnit1013)

Null should not be used for type parameter 'el1' of type 'object'. Use a non-null value, or convert the parameter to a nullable type. (https://xunit.net/xunit.analyzers/rules/xUnit1012)

Null should not be used for type parameter 'el2' of type 'object'. Use a non-null value, or convert the parameter to a nullable type. (https://xunit.net/xunit.analyzers/rules/xUnit1012)

Null should not be used for type parameter 'el1' of type 'object'. Use a non-null value, or convert the parameter to a nullable type. (https://xunit.net/xunit.analyzers/rules/xUnit1012)

Do not use Assert.Equal() to check for collection size. Use Assert.Single instead. (https://xunit.net/xunit.analyzers/rules/xUnit2013)

Possible null reference assignment.

Public method 'Single_element_in_list_of_elements_in_a_structure' on test class 'LazyColumnEnumeratorTest' should be marked as a Fact. Reduce the visibility of the method, or add a Fact attribute to the method. (https://xunit.net/xunit.analyzers/rules/xUnit1013)