单元测试一种创建带有索引的表的方法

Question

I created this fake db for the test, but i don't know how to continue from here. I know that i need to create expected scenarios with yield return and compare the results with expected resulsts and so forth but i can't figure out how to start, I just need a starting point. This is all new to me, so apologies from everyone if this is a dumb question.

public class IndexTests : DataAccessFixture
{
    [Test]
    public void CreateTableWithIndex()
    {
        var db = this.database.Create();
        var table = db.DefineTable("IndexedTable");

        table.Columns.Add("Id", FieldType.Guid, false, true);
        table.Columns.Add("CustomerNumber", FieldType.VarChar, 50);
        table.Columns.Add("Name", FieldType.VarChar, 50);

        table.Indices.Add("IX_Name", false, "Name");
        table.Indices.Add("IX_CustomerNumber", true, "CustomerNumber");

        db.Execute();

        this.database.DropTable(table.Name);
    }
}

Answer 1

First of all you should avoid having a database field in your test class. This can interfere with other tests that may be running concurrently using the same object which may or may not mess with your results (but probably will).

Which one is your fake db? The field database or the results from database.Create() ? If the latter is the case then your test is really just testing your fake code and not your product code.

Since it is not clear if you are using custom types or bcl types i'll just go ahead and assume that you are testing your custom types. If database , db and table are in fact bcl types then read no further. There is no point in testing those classes. That being said, what exactly does db.Execute() do?

You are currently testing multiple things at the same time which should be avoided. Start with a test that creates the table and check if it's there. You also need a test that makes sure there is no exception thrown.

[Test]
public void DefineTableDoesNotThrow() {

    // arrange
    var database = // create your instance here
    var db = database.Create();
    var table = null;

    // act & assert
    Assert.DoesNotThrow(() => table = db.DefineTable("IndexedTable"));

    // clean up
    database.DropTable("IndexedTable");

}

[Test]
public void DefineTable() {

    // arrange
    var database = // create your instance here
    var db = database.Create();

    // act
    var table = db.DefineTable("IndexedTable");

    // assert
    // check if your table was created and exists.
    // do not care about the actual columns in here.

    // clean up
    database.DropTable("IndexedTable");

}

Next you want to test if your columns are created the way you want it. This is another functionality so it should be another test. It works just like DefineTable where you want to make sure it doesn't throw exceptions first and then you worry about if it worked correctly.

[Test]
public void ColumnAddDoesNotThrow() {

    // arrange
    var database = // create your instance here
    var db = database.Create();
    var table = db.DefineTable("IndexedTable");

    // act & assert
    Assert.DoesNotThrow(() => table.Columns.Add("Id", FieldType.Guid, false, true));

    // clean up
    database.DropTable("IndexedTable");

}

[Test]
public void ColumnAdd() {

    // arrange
    var database = // create your instance here
    var db = database.Create();
    var table = db.DefineTable("IndexedTable");

    // act
    table.Columns.Add("Id", FieldType.Guid, false, true);

    // assert
    // check if your table now has the correct column

    // cleanup
    database.DropTable("IndexedTable");

}

The next best thing to do is make that last test use multiple inputs. This allows you to test edge cases with the same code by just adding another line of code. Decorate the test with [TestCaseAttribute(...)] and add the required parameters to your test method. This has to be done for every possible overload of table.Column.Add(...) . Needless to say that this goes for table.Indices.Add(...) just as well.