1 files changed, 54 insertions, 0 deletions
diff --git a/spec/models/experiment_subject_spec.rb b/spec/models/experiment_subject_spec.rb
new file mode 100644
index 00000000000..4850814c5f5
--- /dev/null
+++ b/spec/models/experiment_subject_spec.rb
@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe ExperimentSubject, type: :model do
+  describe 'associations' do
+    it { is_expected.to belong_to(:experiment) }
+    it { is_expected.to belong_to(:user) }
+    it { is_expected.to belong_to(:group) }
+    it { is_expected.to belong_to(:project) }
+  end
+
+  describe 'validations' do
+    it { is_expected.to validate_presence_of(:experiment) }
+
+    describe 'must_have_one_subject_present' do
+      let(:experiment_subject) { build(:experiment_subject, user: nil, group: nil, project: nil) }
+      let(:error_message) { 'Must have exactly one of User, Group, or Project.' }
+
+      it 'fails when no subject is present' do
+        expect(experiment_subject).not_to be_valid
+        expect(experiment_subject.errors[:base]).to include(error_message)
+      end
+
+      it 'passes when user subject is present' do
+        experiment_subject.user = build(:user)
+        expect(experiment_subject).to be_valid
+      end
+
+      it 'passes when group subject is present' do
+        experiment_subject.group = build(:group)
+        expect(experiment_subject).to be_valid
+      end
+
+      it 'passes when project subject is present' do
+        experiment_subject.project = build(:project)
+        expect(experiment_subject).to be_valid
+      end
+
+      it 'fails when more than one subject is present', :aggregate_failures do
+        # two subjects
+        experiment_subject.user = build(:user)
+        experiment_subject.group = build(:group)
+        expect(experiment_subject).not_to be_valid
+        expect(experiment_subject.errors[:base]).to include(error_message)
+
+        # three subjects
+        experiment_subject.project = build(:project)
+        expect(experiment_subject).not_to be_valid
+        expect(experiment_subject.errors[:base]).to include(error_message)
+      end
+    end
+  end
+end