1 files changed, 45 insertions, 0 deletions
diff --git a/spec/graphql/resolvers/user_resolver_spec.rb b/spec/graphql/resolvers/user_resolver_spec.rb
new file mode 100644
index 00000000000..45a8816bf26
--- /dev/null
+++ b/spec/graphql/resolvers/user_resolver_spec.rb
@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Resolvers::UserResolver do
+  include GraphqlHelpers
+
+  describe '#resolve' do
+    let_it_be(:user) { create(:user) }
+
+    context 'when neither an ID or a username is provided' do
+      it 'raises an ArgumentError' do
+        expect { resolve_user }
+        .to raise_error(Gitlab::Graphql::Errors::ArgumentError)
+      end
+    end
+
+    it 'raises an ArgumentError when both an ID and username are provided' do
+      expect { resolve_user(id: user.to_global_id, username: user.username) }
+        .to raise_error(Gitlab::Graphql::Errors::ArgumentError)
+    end
+
+    context 'by username' do
+      it 'returns the correct user' do
+        expect(
+          resolve_user(username: user.username)
+        ).to eq(user)
+      end
+    end
+
+    context 'by ID' do
+      it 'returns the correct user' do
+        expect(
+          resolve_user(id: user.to_global_id)
+        ).to eq(user)
+      end
+    end
+  end
+
+  private
+
+  def resolve_user(args = {})
+    sync(resolve(described_class, args: args))
+  end
+end