Eclipse: enable assertions

1. Go to the menu Run, and then to the menu item Run Configurations.

2. In the left panel, go to Java Application, and then go to Assertions.

3. In the right panel, choose the tab Arguments.

4. Under the field for VM arguments, type -ea to enable assertions.

5. Click on the Apply and then Run button.

To globally set it as the default for everything:

1. Go to menu Window (if you are on Windows), or go to menu Eclipse (if you are on Mac). For Linux it might be something similar.

2. Go to Preferences.

3. Choose Java, and then Installed JREs from the left panel.

4. Select your JRE, and then click the Edit... button in the right panel.

5. In the Default VM arguments field, add -ea.

If you want to solve this issue globally for all JUnit tests then go to Preferences > Java > JUnit and at the top click the checkbox for "Add 'ea' to VM arguments when creating new JUnit launch configuration" Now Eclipse won't bug you for every new test you want to run. For existing tests you have to remove their's run configurations in Run Configuration > JUnit.

To do this globally for all Java runs, edit the Installed JREs properties.

For example: Windows -> Preferences -> highlight the default JRE -> click Edit... -> In the Default VM arguments input box, enter -ea -> click the finish button.

This worked on Eclipse Kepler SR2.