Testing
Ad Hoc Testing
- Very simple testing could work by having a function that tests if the output of our function is equivalent to the expected result we provide outselves.
- However, this testing could be tedious to create if we want to create many different test cases.
- Use JUnit Testing.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
public class TestSort {
/** Tests the sort method of the Sort class. */
public static void testSort() {
String[] input = {"i", "have", "an", "egg"};
String[] expected = {"an", "egg", "have", "i"};
Sort.sort(input);
for (int i = 0; i < input.length; i += 1) {
if (!input[i].equals(expected[i])) {
System.out.println("Mismatch in position " + i + ", expected: " + expected + ", but got: " + input[i] + ".");
break;
}
}
}
public static void main(String[] args) {
testSort();
}
}
JUnit Testing
- Google truth library offers methods to simplify writing tests.
1
%maven com.google.truth:truth:1.1.3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
import static com.google.common.truth.Truth.assertThat;
public class TestSort {
/** Tests the sort method of the Sort class. */
public static void testSort() {
String[] input = {"cows", "dwell", "above", "clouds"};
String[] expected = {"above", "clouds", "cows", "dwell"};
Sort.sort(input);
assertThat(input).isEqualTo(expected);
}
public static void main(String[] args) {
testSort();
}
}
1
2
3
4
5
6
7
8
9
10
11
12
13
| Sort.sort(input);
cannot find symbol
symbol: variable Sort
| assertThat(input).isEqualTo(expected);
cannot access com.google.common.base.Optional
class file for com.google.common.base.Optional not found
1
- As an example, we will write a SelectionSort algorithm to sort an array of strings.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
public class Sort {
private void swap(String[] x, int i, int j) {
String temp = x[i];
x[i] = x[j];
x[j] = temp;
}
public static String findSmallest(String[] x) {
String smallest = x[0];
for (int i = 0; i < x.length; i++) {
if (x[i].compareTo(smallest) < 0) {
smallest = x[i];
}
}
return smallest;
}
public static void sort(String[] x) {
for (int i = 0; i < x.length; i++) {
int minimum = i;
for (int j = i; j < x.length; j++) {
if (x[j].compareTo(x[minimum]) < 0) {
minimum = j;
}
}
swap(x, i, j);
}
}
}
- We may then use JUnit to create a test to validate how our Sort function behaves.
1
2
3
4
5
6
7
8
9
public class TestSort {
@Test
public void testFindSmallest() {
String[] input = {"rawr", "a", "zaza", "newway"};
String expected = "zaza";
String actual = Sort.findSmallest(input);
assertThat(actual).isEqualTo(expected);
}
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
| public class TestSort {
| @Test
| public void testFindSmallest() {
| String[] input = {"rawr", "a", "zaza", "newway"};
| String expected = "zaza";
| String actual = Sort.findSmallest(input);
| assertThat(actual).isEqualTo(expected);
| }
| }
Unresolved dependencies:
- class Test
- method assertThat(java.lang.String)