Show friendly error and prevent NPE when setting invalid QuerySpec op…

…tions in katharsis boot #373

katharsis-core/src/main/java/io/katharsis/core/internal/boot/KatharsisBoot.java

@@ -4,6 +4,7 @@
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.SerializationFeature;
+import net.jodah.typetools.TypeResolver;
 
 import io.katharsis.core.internal.dispatcher.ControllerRegistry;
 import io.katharsis.core.internal.dispatcher.ControllerRegistryBuilder;
@@ -46,7 +47,6 @@
 import io.katharsis.resource.registry.ConstantServiceUrlProvider;
 import io.katharsis.resource.registry.ResourceRegistry;
 import io.katharsis.resource.registry.ServiceUrlProvider;
-import net.jodah.typetools.TypeResolver;
 
 /**
  * Facilitates the startup of Katharsis in various environments (Spring, CDI,
@@ -101,12 +101,26 @@ public void setServiceDiscovery(ServiceDiscovery serviceDiscovery) {
 		moduleRegistry.setServiceDiscovery(serviceDiscovery);
 	}
 
+	/**
+	 * Set the {@link QueryParamsBuilder} to use to parse and handle query parameters.
+	 * When invoked, overwrites previous QueryParamsBuilders and {@link QuerySpecDeserializer}s.
+	 *
+	 * @param queryParamsBuilder
+	 */
 	public void setQueryParamsBuilds(QueryParamsBuilder queryParamsBuilder) {
+		PreconditionUtil.assertNotNull("A query params builder must be provided, but is null", queryParamsBuilder);
 		this.queryParamsBuilder = queryParamsBuilder;
 		this.querySpecDeserializer = null;
 	}
 
+	/**
+	 * Set the {@link QuerySpecDeserializer} to use to parse and handle query parameters.
+	 * When invoked, overwrites previous {@link QueryParamsBuilder}s and QuerySpecDeserializers.
+	 *
+	 * @param querySpecDeserializer
+	 */
 	public void setQuerySpecDeserializer(QuerySpecDeserializer querySpecDeserializer) {
+		PreconditionUtil.assertNotNull("A query spec deserializer must be provided, but is null", querySpecDeserializer);
 		this.querySpecDeserializer = querySpecDeserializer;
 		this.queryParamsBuilder = null;
 	}
@@ -353,11 +367,36 @@ public ServiceDiscovery getServiceDiscovery() {
 		return moduleRegistry.getServiceDiscovery();
 	}
 
+	/**
+	 * Sets the default page limit for requests that return a collection of elements. If the api user does not
+	 * specify the page limit, then this default value will be used.
+	 * <p>
+	 * This is important to prevent denial of service attacks on the server.
+	 * <p>
+	 * NOTE: This using this feature requires a {@link QuerySpecDeserializer} and it does not work with the
+	 * deprecated {@link QueryParamsBuilder}.
+	 *
+	 * @param defaultPageLimit
+	 */
 	public void setDefaultPageLimit(Long defaultPageLimit) {
+		PreconditionUtil.assertNotNull("Setting the default page limit requires using the QuerySpecDeserializer, but " +
+				"it is null. Are you using QueryParams instead?", this.querySpecDeserializer);
 		((DefaultQuerySpecDeserializer) this.querySpecDeserializer).setDefaultLimit(defaultPageLimit);
 	}
 
+	/**
+	 * Sets the maximum page limit allowed for paginated requests.
+	 * <p>
+	 * This is important to prevent denial of service attacks on the server.
+	 * <p>
+	 * NOTE: This using this feature requires a {@link QuerySpecDeserializer} and it does not work with the
+	 * deprecated {@link QueryParamsBuilder}.
+	 *
+	 * @param maxPageLimit
+	 */
 	public void setMaxPageLimit(Long maxPageLimit) {
+		PreconditionUtil.assertNotNull("Setting the max page limit requires using the QuerySpecDeserializer, but " +
+				"it is null. Are you using QueryParams instead?", this.querySpecDeserializer);
 		((DefaultQuerySpecDeserializer) this.querySpecDeserializer).setMaxPageLimit(maxPageLimit);
 	}
 

katharsis-core/src/test/java/io/katharsis/core/internal/boot/KatharsisBootTest.java

@@ -4,15 +4,12 @@
 import java.util.List;
 import java.util.Properties;
 
+import com.fasterxml.jackson.databind.ObjectMapper;
 import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.Mockito;
 
-import com.fasterxml.jackson.databind.ObjectMapper;
-
-import io.katharsis.core.internal.boot.KatharsisBoot;
-import io.katharsis.core.internal.boot.PropertiesProvider;
 import io.katharsis.core.internal.dispatcher.RequestDispatcher;
 import io.katharsis.core.internal.query.QueryAdapterBuilder;
 import io.katharsis.core.internal.query.QuerySpecAdapterBuilder;
@@ -109,6 +106,23 @@ public void setQueryParamsBuilder() {
 		Assert.assertTrue(queryAdapterBuilder instanceof QueryParamsAdapterBuilder);
 	}
 
+
+	@Test(expected = IllegalStateException.class)
+	public void setQueryParamsBuilderErrorsWhenSettingMaxPage() {
+		KatharsisBoot boot = new KatharsisBoot();
+		QueryParamsBuilder deserializer = Mockito.mock(QueryParamsBuilder.class);
+		boot.setQueryParamsBuilds(deserializer);
+		boot.setMaxPageLimit(10L);
+	}
+
+	@Test(expected = IllegalStateException.class)
+	public void setQueryParamsBuilderErrorsWhenSettingDefaultPage() {
+		KatharsisBoot boot = new KatharsisBoot();
+		QueryParamsBuilder deserializer = Mockito.mock(QueryParamsBuilder.class);
+		boot.setQueryParamsBuilds(deserializer);
+		boot.setDefaultPageLimit(10L);
+	}
+
 	@Test
 	public void testServiceDiscovery() {
 		KatharsisBoot boot = new KatharsisBoot();