Testing multiple exceptions in JUnit - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to test that the method throws NullPointerException.

JUnit

assertThrows([1].class, () -> myObject.myMethod(null));

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ANullPointerException

BIllegalArgumentException

CIOException

DRuntimeException

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong exception class like IllegalArgumentException.

Not specifying the exception class at all.

The assertThrows method expects the exception class that should be thrown. Here, NullPointerException.class is correct to test for a null argument.

2fill in blank

medium

Complete the code to test that the method throws either IOException or SQLException.

JUnit

assertThrows([1].class, () -> myObject.myMethod());

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AException

BIOException

CSQLException

DRuntimeException

Attempts:

3 left

💡 Hint

Common Mistakes

Testing only one exception when multiple can be thrown.

Using RuntimeException which does not cover checked exceptions.

Using Exception.class covers multiple checked exceptions like IOException and SQLException in one test.

3fill in blank

hard

Fix the error in the test that expects multiple exceptions using assertThrows.

JUnit

assertThrows([1].class, () -> myObject.myMethod());

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AIOException | SQLException

BException

CSQLException

DIOException

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to use 'IOException | SQLException.class' which is invalid syntax.

Using only one exception class when multiple exceptions can be thrown.

You cannot use the '|' operator inside assertThrows. Instead, use the common superclass Exception.class to catch multiple exceptions.

4fill in blank

hard

Fill both blanks to correctly test that either IllegalArgumentException or NullPointerException is thrown.

JUnit

Throwable thrown = assertThrows([1].class, () -> myObject.myMethod([2]));

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ARuntimeException

Bnull

C"invalid"

DException

Attempts:

3 left

💡 Hint

Common Mistakes

Using Exception.class which is too broad.

Passing a string instead of null to trigger the exception.

Both IllegalArgumentException and NullPointerException extend RuntimeException, so using RuntimeException.class works. Passing null triggers NullPointerException.

5fill in blank

hard

Fill all three blanks to test multiple exceptions and check the exception message.

JUnit

Exception exception = assertThrows([1].class, () -> myObject.myMethod([2]));
assertTrue(exception.getMessage().[3]("error"));

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AException

Bnull

Ccontains

DstartsWith

Attempts:

3 left

💡 Hint

Common Mistakes

Using startsWith() which is more restrictive.

Passing a non-null argument that does not cause exception.

Using Exception.class covers multiple exceptions. Passing null triggers an exception. Checking if the message contains the word "error" verifies the error details.