DefDescriptor<ThemeDef> t1 = addSourceAutoCleanup(ThemeDef.class, "<aura:theme/>");
DefDescriptor<ThemeDef> t2 = addSourceAutoCleanup(ThemeDef.class, "<aura:theme/>");
DefDescriptor<ThemeDef> t3 = addSourceAutoCleanup(ThemeDef.class, "<aura:theme/>");
ctx.appendThemeDescriptor(t1);
ctx.appendThemeDescriptor(t2);
ctx.appendThemeDescriptor(t3);
ThemeList explicit = ctx.getThemeList();
assertEquals(explicit.get(0), t1);
assertEquals(explicit.get(1), t2);
assertEquals(explicit.get(2), t3);