public void IndexOfTests()
        {
            var testContext = _propertyTestData.GetContext();
            var a           = testContext.GetChildElement("a");
            var b           = testContext.GetChildElement("b");
            var c           = testContext.GetChildElement("c");

            var x = new ReadOnlyConfigurationCollection <IChildElement>(null, testContext.ReadOnlyChildConfigurationCollectionPropertyDef,
                                                                        testContext.Configuration.ConfigurationRoot, new ConfigurationObjectSettings());

            Assert.True(x.IndexOf(a) < 0);
            Assert.True(x.IndexOf(b) < 0);
            Assert.True(x.IndexOf(c) < 0);

            x = new ReadOnlyConfigurationCollection <IChildElement>(null, testContext.ReadOnlyChildConfigurationCollectionPropertyDef,
                                                                    testContext.Configuration.ConfigurationRoot, new ConfigurationObjectSettings(), a, b);

            Assert.Equal(0, x.IndexOf(a));
            Assert.Equal(1, x.IndexOf(b));
            Assert.True(x.IndexOf(c) < 0);

            x = new ReadOnlyConfigurationCollection <IChildElement>(null, testContext.ReadOnlyChildConfigurationCollectionPropertyDef,
                                                                    testContext.Configuration.ConfigurationRoot, new ConfigurationObjectSettings(), a, b, c);

            Assert.Equal(0, x.IndexOf(a));
            Assert.Equal(1, x.IndexOf(b));
            Assert.Equal(2, x.IndexOf(c));

            Assert.True(x.IndexOf(null) < 0);

            x.Dispose();
            Assert.Throws <ObjectDisposedException>(() => x.IndexOf(a));
        }
        public void DisposeTests()
        {
            var testContext = _propertyTestData.GetContext();
            var x           = new ReadOnlyConfigurationCollection <IChildElement>(null, testContext.ReadOnlyChildConfigurationCollectionPropertyDef,
                                                                                  testContext.Configuration.ConfigurationRoot, new ConfigurationObjectSettings());

            x.Dispose();
            Assert.Throws <ObjectDisposedException>(() => x.IndexOf(null));
        }