Running DropwizardAppRule before each test in a class using junit - testing

Question

I have a test class that has several tests. At the moment I have this to start up the server, wipe the database etc:
#ClassRule
public static final DropwizardAppRule<ServiceConfig> RULE =
new DropwizardAppRule<ServiceConfig>(ServiceApp.class, ResourceHelpers.resourceFilePath("config.yml"));
All my tests work with this individually. But when I run them all together some fail since other tests modify data. I tried doing the following but I'm getting null pointers when calling RULE.getPort():
#ClassRule
public static DropwizardAppRule<ServiceConfig> RULE;
#Before
public void beforeClass() {
RULE = new DropwizardAppRule<ServiceConfig>(ServiceApp.class, ResourceHelpers.resourceFilePath("config.yml"));
}
I would have expected this to work but it doesn't seem to set the values of RULE properly. Any ideas?

Answer 1

Hi,
I don't know how to handle db "from within" DropwizardAppRule, so I may not really answer your question... I'm actually having another issue myself trying with DropwizardAppRule not properly being setup and torn down between tests. (So if you made progress going this way I'd like you insights).
Anyway, I think you need to handle your DB outside DropwizardAppRule and give it in the Rule. We resolved DB clearing by relying on custom and external TestsRules:
public class CockpitApplicationRule implements TestRule {
public static class App extends CockpitApplication<CockpitConfiguration> {
// only needed because of generics
}
public final DropwizardAppRule<CockpitConfiguration> dw;
public final EmbeddedDatabaseRule db;
public CockpitApplicationRule(String config, ConfigOverride... configOverrides) {
this.db = EmbeddedDatabaseRule.builder()
.initializedByPlugin(LiquibaseInitializer.builder().withChangelogResource("migrations.xml").build())
.build();
this.dw = new DropwizardAppRule<>(App.class, ResourceHelpers.resourceFilePath(config),
ConfigOverride.config("database.url", () -> this.db.getConnectionJdbcUrl()));
}
#Override
#Nullable
public Statement apply(#Nullable Statement base, #Nullable Description description) {
assert base != null;
assert description != null;
return RulesHelper.chain(base, description, dw, RulesHelper.dropDbAfter(db), db);
}
public DSLContext db() {
return DSL.using(db.getConnectionJdbcUrl());
}
}
Basically we override TestRule apply(...) to chain custom Statements. There's our RulesHelper if you want to take a look. That way the DB is cleanly handled by the Rules, we can fill our test DB in test classes using #Before setup methods.
org.zapodot.junit.db.EmbeddedDatabaseRule Is an external dependency that allows us to rather easily instantiate a DB for our tests.
The RulesHelper.dropDbAfter does the actual cleaning:
public static TestRule dropDbAfter(EmbeddedDatabaseRule db) {
return after(() -> DSL.using(db.getConnectionJdbcUrl()).execute("DROP ALL OBJECTS"));
}
You should be able to setup and clean the DB from #Before and #After methods without fully using TestRules though, but I'm not sure it's really easier in the end.
Hope this helped !