Union types must have at least 1 member, and members can be only of Object types, not scalars etc.

Winsor, Daniel · Winsor, Daniel · commit c3fbc2d59476 · 2016-04-29T18:12:05.000-07:00
diff --git a/src/main/java/graphql/Assert.java b/src/main/java/graphql/Assert.java
@@ -1,5 +1,6 @@
 package graphql;
 
+import java.util.Collection;
 
 public class Assert {
 
@@ -9,4 +10,9 @@ public static void assertNotNull(Object object, String errorMessage) {
         throw new AssertException(errorMessage);
     }
 
+    public static void assertNotEmpty(Collection<?> c, String errorMessage) {
+        if (c == null || c.isEmpty()) throw new AssertException(errorMessage);
+        return;
+    }
+
 }
diff --git a/src/main/java/graphql/schema/GraphQLUnionType.java b/src/main/java/graphql/schema/GraphQLUnionType.java
@@ -4,19 +4,20 @@
 import java.util.ArrayList;
 import java.util.List;
 
-import static graphql.Assert.assertNotNull;
+import static graphql.Assert.*;
 
 public class GraphQLUnionType implements GraphQLType, GraphQLOutputType, GraphQLCompositeType, GraphQLUnmodifiedType, GraphQLNullableType {
 
     private final String name;
     private final String description;
-    private List<GraphQLType> types = new ArrayList<GraphQLType>();
+    private List<GraphQLObjectType> types = new ArrayList<GraphQLObjectType>();
     private final TypeResolver typeResolver;
 
 
-    public GraphQLUnionType(String name, String description, List<GraphQLType> types, TypeResolver typeResolver) {
+    public GraphQLUnionType(String name, String description, List<GraphQLObjectType> types, TypeResolver typeResolver) {
         assertNotNull(name, "name can't be null");
         assertNotNull(types, "types can't be null");
+        assertNotEmpty(types, "A Union type must define one or more member types.");
         assertNotNull(typeResolver, "typeResolver can't be null");
         this.name = name;
         this.description = description;
@@ -25,8 +26,8 @@ public GraphQLUnionType(String name, String description, List<GraphQLType> types
     }
 
 
-    public List<GraphQLType> getTypes() {
-        return new ArrayList<GraphQLType>(types);
+    public List<GraphQLObjectType> getTypes() {
+        return new ArrayList<GraphQLObjectType>(types);
     }
 
     public TypeResolver getTypeResolver() {
@@ -49,7 +50,7 @@ public static Builder newUnionType() {
     public static class Builder {
         private String name;
         private String description;
-        private List<GraphQLType> types = new ArrayList<GraphQLType>();
+        private List<GraphQLObjectType> types = new ArrayList<GraphQLObjectType>();
         private TypeResolver typeResolver;
 
         public Builder name(String name) {
@@ -69,14 +70,14 @@ public Builder typeResolver(TypeResolver typeResolver) {
         }
 
 
-        public Builder possibleType(GraphQLType type) {
+        public Builder possibleType(GraphQLObjectType type) {
             assertNotNull(type, "possible type can't be null");
             types.add(type);
             return this;
         }
 
-        public Builder possibleTypes(GraphQLType... type) {
-            for (GraphQLType graphQLType : type) {
+        public Builder possibleTypes(GraphQLObjectType... type) {
+            for (GraphQLObjectType graphQLType : type) {
                 possibleType(graphQLType);
             }
             return this;
diff --git a/src/test/groovy/graphql/schema/GraphQLUnionTypeTest.groovy b/src/test/groovy/graphql/schema/GraphQLUnionTypeTest.groovy
@@ -0,0 +1,24 @@
+package graphql.schema
+
+import spock.lang.Specification
+
+import graphql.AssertException
+import graphql.schema.TypeResolverProxy
+
+import static graphql.schema.GraphQLUnionType.newUnionType
+
+import static graphql.Scalars.GraphQLString
+
+
+class GraphQLUnionTypeTest extends Specification {
+
+    def "no possible types in union fails"() {
+        when:
+        newUnionType()
+                .name("TestUnionType")
+                .typeResolver(new TypeResolverProxy())
+                .build();
+        then:
+        thrown(AssertException)
+    }
+}

Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,6 @@`
`1`	`1`	`package graphql;`
`2`	`2`
	`3`	`+import java.util.Collection;`
`3`	`4`
`4`	`5`	`public class Assert {`
`5`	`6`
`@@ -9,4 +10,9 @@ public static void assertNotNull(Object object, String errorMessage) {`
`9`	`10`	`throw new AssertException(errorMessage);`
`10`	`11`	`}`
`11`	`12`
	`13`	`+ public static void assertNotEmpty(Collection<?> c, String errorMessage) {`
	`14`	`+ if (c == null \|\| c.isEmpty()) throw new AssertException(errorMessage);`
	`15`	`+ return;`
	`16`	`+ }`
	`17`	`+`
`12`	`18`	`}`