Assignment Finished

src/StringCalculator.java

@@ -1,9 +1,94 @@
-
 public class StringCalculator {
-	public int add(String numbersStr) {
-		// Returns the sum of the numbers given in numbersStr
-
-		// not yet implemented
-		return 0;
+
+    // public add method to be implemented and tested - main code 
+	// Returns the sum of the numbers given in numbersStr
+	public int add(String numbersStr) throws StringCalculatorException {
+		int res;
+		if (numbersStr.isEmpty()) // Checking if input is empty
+			return 0;             // Yes - return 0
+		else {
+			res = getSingleNumber(numbersStr); // Calling private method for single number
+			if (res != -1)                     // If ok? -1 is not ok
+				return res;                    // Yes - return method's result
+			else if (numbersStr.contains("\n"))       // If new lines in input
+				return processNewLines(numbersStr);   // then call private method to process
+			else { // Split input into array of numbers, separated by comma
+				String[] numbers = numbersStr.split(",");  
+				if (numbers.length == 0)   // If array's length = 0 - exception 
+					throw new StringCalculatorException();
+				else if (numbers.length == 2)  // exactly 2 numbers
+					return addTwoNum(numbers);  
+				else
+					// And at last - private method for unknown amount of numbers in input
+					return addUnknownAmountNum(numbers);  
+			}
+		}
+	} // End of add method
+
+	// ------------------------------------------------------------------------------------
+	// private methods to use from add method
+	// Note - in case we need to test these methods separately, we should redefine them as public 
+
+
+	// Get an integer number from string input. Returns -1, if input is not number
+	private int getSingleNumber(String str) throws StringCalculatorException {
+		try {
+				int res = Integer.parseInt(str); // Convert string to int
+				if (res < 0)                     // Negative - exception
+					throw new StringCalculatorException();
+				else
+					return res;
+			} catch (NumberFormatException ex) {  // Not number - return -1
+				return -1;
+			}
+	}
+
+	// Process New Lines
+	private int processNewLines(String numbersStr) throws StringCalculatorException {
+		String[] numbers = numbersStr.split("[,\n]");  // Split input into string array,
+		                                               // Separator is comma + new line
+		if (numbers.length == 0)                       // Empty array - exception
+			throw new StringCalculatorException();
+		else if (numbers.length == 2)
+			return addTwoNum(numbers);  
+		else
+			return addUnknownAmountNum(numbers);
 	}
-}
+
+
+	// Returns the sum of two numbers given in string numbers array
+	private int addTwoNum(String[] numbers) throws StringCalculatorException {
+		try {
+			int x1, x2;
+			// Convert both strings to ints and check for negatives
+			// For negatives - StringCalculatorException
+			// For not numbers Integer.parseInt - NumberFormatException
+			if ((x1 = Integer.parseInt(numbers[0])) < 0) 
+				throw new StringCalculatorException();
+			else if ((x2 = Integer.parseInt(numbers[1])) < 0)
+				throw new StringCalculatorException();
+			else
+				return x1 + x2; // All ok - return sum of 2 numbers
+			} catch (NumberFormatException ex) {
+				throw new StringCalculatorException();
+			}
+	}
+
+
+	// Returns the sum of the numbers given in string numbers array
+	private int addUnknownAmountNum(String[] numbers) throws StringCalculatorException {
+		int sum = 0; // Initialize sum
+		for (int i = 0; i < numbers.length; i++) // Loop through...
+			try {
+				int n = Integer.parseInt(numbers[i]); // Convert string to int
+				if (n < 0) // Negative - exception
+					throw new StringCalculatorException();
+				else sum += n; // add to sum
+			} catch (NumberFormatException ex) { // Check for not number - exception
+				throw new StringCalculatorException();
+			}
+		return sum;
+	}
+
+
+} // End of class

tests/StringCalculatorTest.java

@@ -1,12 +1,103 @@
 import static org.junit.Assert.*;
 
+import org.junit.Before;
 import org.junit.Test;
 
 public class StringCalculatorTest {
 
+	private StringCalculator stcalc; // Define an object
+
+	@Before
+	public void init() {
+		stcalc = new StringCalculator(); // and create it
+	}
+
+
+	// Set of test cases below
+
 	@Test
-	public void test() {
-		fail("Not yet implemented");
+	public void test_empty_string() throws StringCalculatorException {
+		assertEquals(0, stcalc.add(""));
 	}
-
-}
+
+	@Test
+	public void test_single_number() throws StringCalculatorException {
+		assertEquals(10, stcalc.add("10"));
+	}
+
+	@Test
+	public void test_two_numbers() throws StringCalculatorException {
+		assertEquals(10, stcalc.add("6,4"));
+		assertEquals(3, stcalc.add("1,2"));
+		assertEquals(2, stcalc.add("0,2"));
+	}
+
+	@Test
+	public void test_any_numbers() throws StringCalculatorException {
+		assertEquals(8, stcalc.add("1,3,4"));
+		assertEquals(0, stcalc.add("0,0,0"));
+		assertEquals(10, stcalc.add("1,2,3,4"));
+	}
+
+	@Test(expected = StringCalculatorException.class)
+	public void test_single_not_number() throws StringCalculatorException {
+		stcalc.add("abc");
+
+	}
+
+	@Test(expected = StringCalculatorException.class)
+	public void test_single_not_number2() throws StringCalculatorException {
+		stcalc.add(",");
+	}
+
+	@Test(expected = StringCalculatorException.class)
+	public void test_two_not_number() throws StringCalculatorException {
+		stcalc.add("abc,def");
+	}
+
+	@Test(expected = StringCalculatorException.class)
+	public void test_two_not_number2() throws StringCalculatorException {
+		stcalc.add("10,aaa");
+	}
+
+	@Test(expected = StringCalculatorException.class)
+	public void test_single_negative_number() throws StringCalculatorException {
+		stcalc.add("-1");
+	}
+
+	@Test(expected = StringCalculatorException.class)
+	public void test_two_negative_numbers() throws StringCalculatorException {
+		stcalc.add("-1,-2");
+	}
+
+	@Test(expected = StringCalculatorException.class)
+	public void test_two_negative_numbers2() throws StringCalculatorException {
+		stcalc.add("-2,4");
+	}
+
+	@Test(expected = StringCalculatorException.class)
+	public void test_two_negative_numbers3() throws StringCalculatorException {
+		stcalc.add("5,-6");
+	}
+
+	@Test(expected = StringCalculatorException.class)
+	public void test_more_than_two_negative_numbers() throws StringCalculatorException {
+		stcalc.add("-5,-8,2,-1");
+	}
+
+	@Test
+	public void test_two_numbers_line_break() throws StringCalculatorException {
+		assertEquals(10, stcalc.add("4\n6"));
+		assertEquals(5, stcalc.add("0\n5"));
+	}
+
+	@Test
+	public void more_than_two_numbers_line_break() throws StringCalculatorException {
+		assertEquals(6, stcalc.add("1\n2,3"));
+		assertEquals(6, stcalc.add("1,2\n3"));
+		assertEquals(6, stcalc.add("1\n2\n3"));
+	}
+
+	// More tests can go here
+
+} // End of test class