Improve unit tests

[vldtecno]

Improve unit tests so that they better reflect the requirements of each component.

Select and use one of the unit test naming conventions mentioned here: https://dzone.com/articles/7-popular-unit-test-naming

MethodName_StateUnderTest_ExpectedBehavior: There are arguments against this strategy that if method names change as part of code refactoring than test name like this should also change or it becomes difficult to comprehend at a later stage. Following are some of the example:
    isAdult_AgeLessThan18_False
    withdrawMoney_InvalidAccount_ExceptionThrown
    admitStudent_MissingMandatoryFields_FailToAdmit
MethodName_ExpectedBehavior_StateUnderTest: Slightly tweeked from above, but a section of developers also recommend using this naming technique. This technique also has disadvantage that if method names get changed, it becomes difficult to comprehend at a later stage. Following is how tests in first example would read like if named using this technique:
    isAdult_False_AgeLessThan18
    withdrawMoney_ThrowsException_IfAccountIsInvalid
    admitStudent_FailToAdmit_IfMandatoryFieldsAreMissing
test[Feature being tested]: This one makes it easy to read the test as the feature to be tested is written as part of test name. Although, there are arguments that the “test” prefix is redundant. However, some sections of developer love to use this technique. Following is how the above tests would read like if named using this technique:
    testIsNotAnAdultIfAgeLessThan18
    testFailToWithdrawMoneyIfAccountIsInvalid
    testStudentIsNotAdmittedIfMandatoryFieldsAreMissing
Feature to be tested: Many suggests that it is better to simply write the feature to be tested because one is anyway using annotations to identify method as test methods. It is also recommended for the reason that it makes unit tests as alternate form of documentation and avoid code smells. Following is how tests in first example would read like if named using this technique:
    IsNotAnAdultIfAgeLessThan18
    FailToWithdrawMoneyIfAccountIsInvalid
    StudentIsNotAdmittedIfMandatoryFieldsAreMissing
Should_ExpectedBehavior_When_StateUnderTest: This technique is also used by many as it makes it easy to read the tests. Following is how tests in first example would read like if named using this technique:
    Should_ThrowException_When_AgeLessThan18
    Should_FailToWithdrawMoney_ForInvalidAccount
    Should_FailToAdmit_IfMandatoryFieldsAreMissing
When_StateUnderTest_Expect_ExpectedBehavior: Following is how tests in first example would read like if named using this technique:
    When_AgeLessThan18_Expect_isAdultAsFalse
    When_InvalidAccount_Expect_WithdrawMoneyToFail
    When_MandatoryFieldsAreMissing_Expect_StudentAdmissionToFail
Given_Preconditions_When_StateUnderTest_Then_ExpectedBehavior: This approach is based on naming convention developed as part of Behavior-Driven Development (BDD). The idea is to break down the tests into three part such that one could come up with preconditions, state under test and expected behavior to be written in above format. Following is how tests in first example would read like if named using this technique:
    Given_UserIsAuthenticated_When_InvalidAccountNumberIsUsedToWithdrawMoney_Then_TransactionsWillFail