test: check 377 issue that projection works

relates #377

src/__tests__/github_issues/377-test.ts

@@ -0,0 +1,99 @@
+import { SchemaComposer, graphql } from 'graphql-compose';
+import { composeMongoose } from '../../index';
+import { mongoose } from '../../__mocks__/mongooseCommon';
+import { Schema } from 'mongoose';
+
+const schemaComposer = new SchemaComposer<{ req: any }>();
+
+// mongoose.set('debug', true);
+
+const PrevisitSchema = new Schema(
+  {
+    name: {
+      type: String,
+      required: true,
+      trim: true,
+    },
+    project_id: { type: Schema.Types.ObjectId, required: true },
+  },
+  {
+    collection: 'previsits',
+  }
+);
+const PrevisitModel = mongoose.model<any>('Previsit', PrevisitSchema);
+const PrevisitTC = composeMongoose(PrevisitModel, { schemaComposer });
+
+const ProjectSchema = new Schema(
+  {
+    name: {
+      type: String,
+      required: true,
+      trim: true,
+      unique: true,
+    },
+  },
+  {
+    collection: 'projects',
+  }
+);
+const ProjectModel = mongoose.model<any>('Project', ProjectSchema);
+const ProjectTC = composeMongoose(ProjectModel, { schemaComposer });
+
+PrevisitTC.addRelation('project', {
+  resolver: () => ProjectTC.mongooseResolvers.dataLoader({ lean: true }),
+  prepareArgs: {
+    _id: (source) => source.project_id || null,
+  },
+  projection: { project_id: 1 },
+});
+
+schemaComposer.Query.addFields({
+  previsitMany: PrevisitTC.mongooseResolvers.findMany(),
+});
+
+const schema = schemaComposer.buildSchema();
+
+beforeAll(async () => {
+  await ProjectModel.base.createConnection();
+  const projects = await ProjectModel.create([
+    { name: 'Project1' },
+    { name: 'Project2' },
+    { name: 'Project3' },
+  ]);
+  await PrevisitModel.create([
+    { name: 'Previsit1', project_id: projects[0] },
+    { name: 'Previsit2', project_id: projects[1] },
+    { name: 'Previsit3', project_id: projects[2] },
+  ]);
+});
+afterAll(() => {
+  ProjectModel.base.disconnect();
+});
+
+describe('issue #377 - Missing fields from projection in addRelation', () => {
+  it('check', async () => {
+    const result = await graphql.graphql({
+      schema,
+      contextValue: {},
+      source: `
+        {
+          previsitMany {
+            name
+            project {
+              name
+            }
+          }
+        }
+      `,
+    });
+    expect(result).toEqual({
+      data: {
+        previsitMany: [
+          { name: 'Previsit1', project: { name: 'Project1' } },
+          { name: 'Previsit2', project: { name: 'Project2' } },
+          { name: 'Previsit3', project: { name: 'Project3' } },
+        ],
+      },
+    });
+  });
+});