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Unit Testing a C# or Java function in NUnit or JUnit which doesn't take an input argument. How to

Hi there;

I have been trying to test my functions which I wrote in C# and Java, but when the function takes no input argument and calls other functions in it. I have no clue how I can arrange the test functions. This is same in C# and Java. I am using NUnit and JUnit respectively.

I have 3 basic problems actually:
1) What if the function to be tested receives no input arguments
2) What if the function to be tested calls other functions (should I test the other functions individually or within the target function?)
3) No return values or global variables such as ArrayLists or Dictionaries..

Following code covers, the first 2. I want to test some dummy files apart from the List.txt file, but I don't know how I can set the test case since the filepath is not passed and is not even global to the class..

 public bool Read()
        {
            string line;
            alist = new SortedDictionary<string, string>();

            using (StreamReader sr = new StreamReader("List.txt"))
            {
                while ((line = sr.ReadLine()) != null)
                {
                    try
                    {
                        // Splitting line into atoms where the first atom represents prefix, and third atom represents a operator numerical code                                                        
                        if (!line.StartsWith("O"))
                        {
                            string[] atoms = line.Split(new char[] { ' ', '\t' });
                            Prefix = atoms[0];
                            Price = atoms[2];
                            Search();
                        }
                        else
                        {
                            Display();
                            alist.Clear();
                            Letter = line[line.Length - 2];
                        }
                    }
                    catch (FileNotFoundException e)
                    {
                        return false;
                    }
                }
                sr.Close();
                return true;
            }
        }

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Test case is as follows:

 [Test]
        public void CanRead_Absolute_Path()
        {
            // Arrange
----------->            string path = "ListEmpty.txt";  I cannot pass the file name...What should I do? Should I read it?
            var target = new Routing();
            var expected = true;

            // Actual
            var actual = target.Read();
----------->when you check above read function, there are display function and a arraylist clearing...How can I populate this?
            // Assert
            Assert.AreEqual(expected, actual);
        }

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Regards.

SOLUTION

topdog770

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jazzIIIlove

ASKER

Hi;

Thanks for the comment. Ok, let's see. Following is another code segment, this time in Java and Junit:

It's straight forward, reads a file and inside this function, another function call is made.

public boolean read(String filePath)
	{
		try{
			// Open the file that is the first command line parameter
			FileInputStream fstream = new FileInputStream(filePath);

			// Get the object of DataInputStream
			DataInputStream in = new DataInputStream(fstream);
			BufferedReader br = new BufferedReader(new InputStreamReader(in));

			String strLine;
			//Read File Line By Line
			while ((strLine = br.readLine()) != null)   {
				split(strLine);				
			}			
			//Close the input stream
			in.close();
			return true;

		}catch (Exception e){//Catch exception if any
			System.out.println("Error: " + e.getMessage());
			return false;
		}
	}

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The problem is that split() function causes null pointer exceptions. I just want to skip that line as nothing happens in JUnit. Possible? I googled a lot but couldn't find out any example. Can you help?

Is it the "mock"ing thing in testing world?

Regards.

jazzIIIlove

ASKER

Hi as an update;
I installed mockito jar and try to invoke doNothing function as follows:
      public void readTestRegularTextFile()
      {
            // Arrange
            Routing r = new Routing();            //read and split functions reside in this class
            Mockito.doNothing().when(r).split("");
            boolean actual = r.read("List.txt");
            boolean expected = true;

The problem is that it's not working, and moreover, the split(..) function content changes for every line read. So, what to do? I am just trying to proof the files are read.

Regards.

ASKER CERTIFIED SOLUTION

topdog770

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jazzIIIlove

ASKER

Good points. Thanks.