@Test
    public void testMissingKey() {
        val client = getClient();
        client.setKey(null);
        TestsHelper.expectException(() -> client.getRedirectionAction(
            new CallContext(MockWebContext.create(), new MockSessionStore())),
            TechnicalException.class, "key cannot be blank");
    }
This class tests the {@link OAuth20Client} class.

@author Jerome Leleu
@since 1.0.0
pac4j-oauth/src/test/java/org/pac4j/oauth/client/OAuth20ClientTests.java