add rspec tests

spec/models/meeting_spec.rb

@@ -0,0 +1,19 @@
+require "rails_helper"
+
+describe Meeting, type: :model do
+
+  it "should be valid." do
+    meeting = create(:meeting)
+    expect(meeting).to be_valid
+  end
+
+  it "name should be present." do
+    meeting = build(:meeting, name: nil)
+    expect(meeting).to_not be_valid
+  end
+
+  it "#random_password is random." do
+    meeting = create(:meeting)
+    expect(meeting.send(:random_password, 10)).to_not eql(meeting.send(:random_password, 10))
+  end
+end