Use default Query type if it isn't defined in the introspection result (#537)

Author: vepanimas

src/main/com/intellij/lang/jsgraphql/ide/introspection/GraphQLIntrospectionResultToSchema.java

@@ -39,15 +39,16 @@ public Document createSchemaDefinition(@NotNull Map<String, Object> introspectio
         assertTrue(introspectionResult.get("__schema") != null, () -> "__schema expected");
         Map<String, Object> schema = (Map<String, Object>) introspectionResult.get("__schema");
 
+        SchemaDefinition.Builder schemaDefinition = SchemaDefinition.newSchemaDefinition();
 
         Map<String, Object> queryType = (Map<String, Object>) schema.get("queryType");
-        assertNotNull(queryType, () -> "queryType expected");
-        TypeName query = TypeName.newTypeName().name((String) queryType.get("name")).build();
-        boolean nonDefaultQueryName = !"Query".equals(query.getName());
-
-        SchemaDefinition.Builder schemaDefinition = SchemaDefinition.newSchemaDefinition();
-        schemaDefinition.operationTypeDefinition(
-            OperationTypeDefinition.newOperationTypeDefinition().name("query").typeName(query).build());
+        boolean nonDefaultQueryName = false;
+        if (queryType != null) {
+            TypeName query = TypeName.newTypeName().name((String) queryType.get("name")).build();
+            nonDefaultQueryName = !"Query".equals(query.getName());
+            schemaDefinition.operationTypeDefinition(
+                OperationTypeDefinition.newOperationTypeDefinition().name("query").typeName(query).build());
+        }
 
         Map<String, Object> mutationType = (Map<String, Object>) schema.get("mutationType");
         boolean nonDefaultMutationName = false;

src/test/com/intellij/lang/jsgraphql/introspection/GraphQLIntrospectionServiceTest.java

@@ -55,6 +55,14 @@ public void testPrintIntrospectionWithUndefinedDirectives() {
         doTest("schemaWithUndefinedDirectives.json", "schemaWithUndefinedDirectives.graphql");
     }
 
+    public void testPrintIntrospectionWithoutRootTypes() {
+        doTest("schemaWithoutRootTypes.json", "schemaWithoutRootTypes.graphql");
+    }
+
+    public void testPrintIntrospectionWithCustomRootTypes() {
+        doTest("schemaWithCustomRootTypes.json", "schemaWithCustomRootTypes.graphql");
+    }
+
     private void doTest(@NotNull String source, @NotNull String expected) {
         myFixture.configureByText(
             "result.graphql",

test-resources/testData/graphql/introspection/schemaWithCustomRootTypes.graphql

@@ -0,0 +1,21 @@
+schema {
+    query: CustomQuery
+    mutation: CustomMutation
+    subscription: CustomSubscription
+}
+
+type CustomMutation {
+    createUser: User
+}
+
+type CustomQuery {
+    user: User
+}
+
+type CustomSubscription {
+    users: [User]
+}
+
+type User {
+    name: String
+}