Unit Testing: Scenario

I was forwarded the following question:

Good afternoon! I was hoping that you might have some advice or guidance on unit test coding in C#? I have read a lot on this and researched it on the internet. The internship has me doing a lot of it right now. I am still confused about how to exactly to approach it, what would be a good strategy? I believe it is similar to validation. Any help would be appreciated.

To show a little bit about how unit tests can be applied in C#, consider this actual customer request which I handled today.

We would like to modify how the “Description/Keywords” field functions as follows:

Search by “Description/Keywords”

  1. A search for 1 keyword will display all firms that have the keyword in description field (as it currently functions)
  2. A search for 2 or more keywords will display all firms that have ANY or ALL keywords in description field, depending on user selection.
  3. We will be removing ”Starts with” and ”Contains” radio buttons for this item only.

The field search used to be based on a contains/starts with option that matched entire substrings. Now the user wants to match keywords in any order. Can we implement this change with the assistance of unit testing?

Start by declaring a method signature to accomplish the task desired:

public enum SEARCH_KEYWORDS { All, Any };
bool SearchKeywords(string haystack, 
    string needle, 
    SEARCH_KEYWORDS stype) { ... }

The body of the method may simply throw a NotImplementedException, or return false.

Next, we can create some unit tests describing functionality that is desired.

For example, it should match or not a single word, regardless of any/all.

[TestMethod()]
public void SearchKeywordsSingleWord()
{
    PublicSearchQueryBC target = new PublicSearchQueryBC();
    Assert.AreEqual(true, target.SearchKeywords("word", "word", PublicSearchQueryDTO.SEARCH_KEYWORDS.Any));
    Assert.AreEqual(true, target.SearchKeywords("word", "word", PublicSearchQueryDTO.SEARCH_KEYWORDS.All));
    Assert.AreEqual(false, target.SearchKeywords("words", "word", PublicSearchQueryDTO.SEARCH_KEYWORDS.Any));
    Assert.AreEqual(false, target.SearchKeywords("words", "word", PublicSearchQueryDTO.SEARCH_KEYWORDS.All));
    Assert.AreEqual(false, target.SearchKeywords("word", "words", PublicSearchQueryDTO.SEARCH_KEYWORDS.Any));
    Assert.AreEqual(false, target.SearchKeywords("word", "words", PublicSearchQueryDTO.SEARCH_KEYWORDS.All));
}

It should match or not a phrase, depending on the phrase and whether any/all is selected. (Note: you might instead wish to divide up the tests as “tests for any” and separately, “tests for all”)

[TestMethod()]
public void SearchKeywordsPhrase()
{
    PublicSearchQueryBC target = new PublicSearchQueryBC();
    Assert.AreEqual(true, target.SearchKeywords("lazy fox jumping bridge", "fox jumping lazy bridge", PublicSearchQueryDTO.SEARCH_KEYWORDS.All));
    Assert.AreEqual(true, target.SearchKeywords("lazy fox jumping bridge", "fox jumping lazy bridge", PublicSearchQueryDTO.SEARCH_KEYWORDS.Any));
            
    Assert.AreEqual(false, target.SearchKeywords("lazy fox jumping bridge", "lazy fox jumping goat bridge", PublicSearchQueryDTO.SEARCH_KEYWORDS.All));
    Assert.AreEqual(true, target.SearchKeywords("lazy fox jumping bridge", "lazy fox jumping goat bridge", PublicSearchQueryDTO.SEARCH_KEYWORDS.Any));

    Assert.AreEqual(false, target.SearchKeywords("lazy fox jumping bridge", "fox jumping lazy goat bridge", PublicSearchQueryDTO.SEARCH_KEYWORDS.All));
    Assert.AreEqual(true, target.SearchKeywords("lazy fox jumping bridge", "fox jumping lazy goat bridge", PublicSearchQueryDTO.SEARCH_KEYWORDS.Any));

    Assert.AreEqual(true, target.SearchKeywords("lazy fox goat jumping bridge", "fox jumping lazy  bridge", PublicSearchQueryDTO.SEARCH_KEYWORDS.All));
    Assert.AreEqual(true, target.SearchKeywords("lazy fox goat jumping bridge", "fox jumping lazy  bridge", PublicSearchQueryDTO.SEARCH_KEYWORDS.Any));

    Assert.AreEqual(false, target.SearchKeywords("lazy fox jumping bridge", "goat rubber ducky", PublicSearchQueryDTO.SEARCH_KEYWORDS.All));
    Assert.AreEqual(false, target.SearchKeywords("lazy fox jumping bridge", "goat rubber ducky", PublicSearchQueryDTO.SEARCH_KEYWORDS.Any));

}

You can think about other kinds of special cases that might be encountered. Should the search be case sensitive? Probably not, so better add tests to make sure it isn’t. Should the search consider punctuation? Definitely not, since it’s keywords. What about blank spaces? Blanks should never match (that’s my opinion), so add tests for it.

[TestMethod()]
public void SearchKeywordsPhraseCap()
{
    PublicSearchQueryBC target = new PublicSearchQueryBC();
    Assert.AreEqual(true, target.SearchKeywords("LAZY FOX jUMPING Bridge", "fox jumping lazy bridge", PublicSearchQueryDTO.SEARCH_KEYWORDS.All));
    Assert.AreEqual(true, target.SearchKeywords("LAZY FOX jUMPING Bridge", "fox jumping lazy bridge", PublicSearchQueryDTO.SEARCH_KEYWORDS.Any));

    Assert.AreEqual(false, target.SearchKeywords("LAZY FOX jUMPING Bridge", "fox jumping goat bridge", PublicSearchQueryDTO.SEARCH_KEYWORDS.All));
    Assert.AreEqual(true, target.SearchKeywords("LAZY FOX jUMPING Bridge", "fox jumping goat bridge", PublicSearchQueryDTO.SEARCH_KEYWORDS.Any));

}

[TestMethod()]
public void SearchKeywordsPunc()
{
    PublicSearchQueryBC target = new PublicSearchQueryBC();
    Assert.AreEqual(true, target.SearchKeywords("lazy, fox: jumping-bridge", "fox jumping lazy bridge", PublicSearchQueryDTO.SEARCH_KEYWORDS.All));
    Assert.AreEqual(true, target.SearchKeywords("lazy, fox: jumping-bridge", "fox-jumping. lazy, bridge", PublicSearchQueryDTO.SEARCH_KEYWORDS.All));
            

}


[TestMethod()]
public void SearchKeywordsBlanks()
{
    PublicSearchQueryBC target = new PublicSearchQueryBC();
    Assert.AreEqual(false, target.SearchKeywords("lazy fox jumping bridge", "", PublicSearchQueryDTO.SEARCH_KEYWORDS.All));
    Assert.AreEqual(false, target.SearchKeywords("lazy fox jumping bridge", "", PublicSearchQueryDTO.SEARCH_KEYWORDS.Any));

    Assert.AreEqual(false, target.SearchKeywords("", "", PublicSearchQueryDTO.SEARCH_KEYWORDS.All));
    Assert.AreEqual(false, target.SearchKeywords("", "", PublicSearchQueryDTO.SEARCH_KEYWORDS.Any));

    Assert.AreEqual(false, target.SearchKeywords("  ", "", PublicSearchQueryDTO.SEARCH_KEYWORDS.All));
    Assert.AreEqual(false, target.SearchKeywords("", "    ", PublicSearchQueryDTO.SEARCH_KEYWORDS.Any));

    Assert.AreEqual(false, target.SearchKeywords("", "lazy fox jumping bridge", PublicSearchQueryDTO.SEARCH_KEYWORDS.All));
    Assert.AreEqual(false, target.SearchKeywords("", "lazy fox jumping bridge", PublicSearchQueryDTO.SEARCH_KEYWORDS.Any));
            
}

Now run the tests. They should all (or almost, depending on the naiveness of the original implementation) fail. That’s fine. Next, go ahead and implement the method, and run the tests again.

no blank

Looks like a test is failing. Turns out my initial implementation didn’t handle blanks the way I expected. So I went ahead and fixed it, and ran the tests again.

fixed blanks

This is where the tests really start to shine. I fixed the blank issue, but, in the progress, accidentally introduced another bug! Once all the bugs are resolved, all tests should pass.

This is a good time to refactor the implementation and make it cleaner, if needed. The tests should be used to ensure functionality isn’t damaged. This is a pattern known as Red-Green-Refactor.

Let’s say you then send the implementation to QA, and a bug is reported. The first step is to add a new failing test reproducing the bug. Then, proceed to fix the bug. You’ll have confidence that the bug is fixed and no regression has occurred when all tests are again showing green.