Testerina is the test framework built for the Ballerina language. This will be a part of ballerina-tools-<release-version>.zip distribution [1].

Testerina provides ballerina test command.

Once you run tests using ballerina test command, Testerina will print a summary of test results on the console.

To test a file written in Ballerina language, use the test command as follows.
./ballerina test <package_name>

package ballerina.test;

• startService(string servicename)
• assertTrue(boolean condition)
• assertTrue(boolean condition, string message)
• assertFalse(boolean condition)
• assertFalse(boolean condition, string message)
• assertEquals(string actual, string expected)
• assertEquals(string actual, string expected, string message)
• assertEquals(int actual, int expected)
• assertEquals(int actual, int expected, string message)
• assertEquals(float actual, float expected)
• assertEquals(float actual, float expected, string message)
• assertEquals(boolean actual, boolean expected)
• assertEquals(boolean actual, boolean expected, string message)
• assertEquals(string[] actual, string[] expected)
• assertEquals(string[] actual, string[] expected, string message)
• assertEquals(float[] actual, float[] expected)
• assertEquals(float[] actual, float[] expected, string message)
• assertEquals(int[] actual, int[] expected)
• assertEquals(int[] actual, int[] expected, string message)

package ballerina.mock;

• setValue(string pathExpressionToMockableConnector)

• Test files should contain _test.bal suffix.
• Test functions should contain test prefix.
  e.g.: testAddTwoNumbers()
• Each test function may contain one or more asserts.
  e.g. 1:

import ballerina.test;
function testAddTwoNumbers() {
    test:assertEquals(addTwoNumbers(1, 2), 3, "Number addition failed for positive numbers");
    test:assertEquals(addTwoNumbers(-1, -2), -3, "Number addition failed for negative numbers");
    test:assertEquals(addTwoNumbers(0, 0), 0, "Number addition failed for number zero");
}

e.g. 2: This example shows how to test ballerina service with the back-end mocking support.

import ballerina.mock;
import ballerina.test;
import ballerina.lang.messages;

function testService() {
    string serviceURL = test:startService("helloWorld");
    string mockedTwitterServiceURL = test:startService("mockedTwitterService");
    mock:setValue("helloWorld.myTwitterConnectorInstance.myHttpConnector.serviceUri", mockedTwitterServiceURL);
    
    http:ClientConnector client = create http:ClientConnector(serviceURL);
    message request = {};
    message response = {};
    response = http:ClientConnector.get(client, "/", request);
    string payload = messages:getStringPayload(response);
    test:assertEquals(payload, "<expectedOutput/>");
}

A complete sample can be found at samples/mock/ directory.

If at least one assert fails, whole test function will be marked as failed. Detailed information is shown in the test result summary.

One package may contain more than one *._test.bal file.

1 Download [1] ballerina-tools-<release-version>.zip distribution and unzip.
2 Unzip and go to ballerina-tools-<release-version>.
3 Create a directory samples/foo/bar.
4 Create the following two files inside this directory.

e.g.: sample.bal

package samples.foo.bar;

import ballerina.lang.system;
 
function main (string[] args) {
    int i = intAdd(1, 2);
    system:println("Result: " + i);
}
 
function intAdd(int a, int b) (int) {
    return a + b;
}

e.g.: sample_test.bal

package samples.foo.bar;
 
import ballerina.test;
 
function testInt() {	
    int answer = 0;
    answer = intAdd(1, 2);
    test:assertEquals(answer, 3, "IntAdd function failed");
	
}

Note the package hierarchy in above files.

5 Run tests using following command.
> ./bin/ballerina test samples/foo/bar/

Following is a sample console output.

test 'testInt' failed: <Detail error message>
 
result:  
tests run: 1, passed: 0, failed: 1
failed tests:
 testInt: <Detail error message>

• Download ballerina-tools-<release-version>.zip distribution and unzip.
• Copy samples/mock directory to ballerina-tools-<release-version>.
• Run tests as follows.
  > ./bin/ballerina test mock/

[1] https://github.com/ballerinalang/distribution