System.Tests.StringTests.Format_Invalid C# (CSharp) Method

        public static void Format_Invalid()
        {
            var formatter = new TestFormatter();
            var obj1 = new object();
            var obj2 = new object();
            var obj3 = new object();
            var obj4 = new object();

            // Format is null
            Assert.Throws<ArgumentNullException>("format", () => string.Format(null, obj1));
            Assert.Throws<ArgumentNullException>("format", () => string.Format(null, obj1, obj2));
            Assert.Throws<ArgumentNullException>("format", () => string.Format(null, obj1, obj2, obj3));
            Assert.Throws<ArgumentNullException>("format", () => string.Format(null, obj1, obj2, obj3, obj4));

            Assert.Throws<ArgumentNullException>("format", () => string.Format(formatter, null, obj1));
            Assert.Throws<ArgumentNullException>("format", () => string.Format(formatter, null, obj1, obj2));
            Assert.Throws<ArgumentNullException>("format", () => string.Format(formatter, null, obj1, obj2, obj3));

            // Args is null
            Assert.Throws<ArgumentNullException>("args", () => string.Format("", null));
            Assert.Throws<ArgumentNullException>("args", () => string.Format(formatter, "", null));

            // Args and format are null
            Assert.Throws<ArgumentNullException>("format", () => string.Format(null, (object[])null));
            Assert.Throws<ArgumentNullException>("format", () => string.Format(formatter, null, null));

            // Format has value < 0
            Assert.Throws<FormatException>(() => string.Format("{-1}", obj1));
            Assert.Throws<FormatException>(() => string.Format("{-1}", obj1, obj2));
            Assert.Throws<FormatException>(() => string.Format("{-1}", obj1, obj2, obj3));
            Assert.Throws<FormatException>(() => string.Format("{-1}", obj1, obj2, obj3, obj4));
            Assert.Throws<FormatException>(() => string.Format(formatter, "{-1}", obj1));
            Assert.Throws<FormatException>(() => string.Format(formatter, "{-1}", obj1, obj2));
            Assert.Throws<FormatException>(() => string.Format(formatter, "{-1}", obj1, obj2, obj3));
            Assert.Throws<FormatException>(() => string.Format(formatter, "{-1}", obj1, obj2, obj3, obj4));

            // Format has out of range value
            Assert.Throws<FormatException>(() => string.Format("{1}", obj1));
            Assert.Throws<FormatException>(() => string.Format("{2}", obj1, obj2));
            Assert.Throws<FormatException>(() => string.Format("{3}", obj1, obj2, obj3));
            Assert.Throws<FormatException>(() => string.Format("{4}", obj1, obj2, obj3, obj4));
            Assert.Throws<FormatException>(() => string.Format(formatter, "{1}", obj1));
            Assert.Throws<FormatException>(() => string.Format(formatter, "{2}", obj1, obj2));
            Assert.Throws<FormatException>(() => string.Format(formatter, "{3}", obj1, obj2, obj3));
            Assert.Throws<FormatException>(() => string.Format(formatter, "{4}", obj1, obj2, obj3, obj4));
        }