work on review comments

src/System.Text.Json/src/System/Text/Json/Node/JsonNumber.cs

@@ -26,6 +26,7 @@ public class JsonNumber : JsonNode, IEquatable<JsonNumber>
         /// <exception cref="ArgumentException">
         ///   Provided value is not in a legal JSON number format.
         /// </exception>
+        /// <remarks>Provided value is stored in the same format as passed.</remarks> 
         public JsonNumber(string value) => SetFormattedValue(value);
 
         /// <summary>
@@ -162,6 +163,12 @@ public class JsonNumber : JsonNode, IEquatable<JsonNumber>
         /// <exception cref="FormatException">
         ///   <see cref="JsonNumber"/> represents a number in a format not compliant with <see cref="float"/>.
         /// </exception>
+        /// <remarks> 
+        ///   On .NET Core this method does not return <see langword="false"/> for values larger than 
+        ///   <see cref="float.MaxValue"/> (or smaller than <see cref="float.MinValue"/>), 
+        ///   instead <see langword="true"/> is returned and <see cref="float.PositiveInfinity"/> (or 
+        ///   <see cref="float.NegativeInfinity"/>) is emitted. 
+        /// </remarks> 
         public float GetSingle() => float.Parse(_value);
 
         /// <summary>
@@ -174,6 +181,12 @@ public class JsonNumber : JsonNode, IEquatable<JsonNumber>
         /// <exception cref="FormatException">
         ///   <see cref="JsonNumber"/> represents a number in a format not compliant with <see cref="double"/>.
         /// </exception>
+        /// <remarks> 
+        ///   On .NET Core this method does not return <see langword="false"/> for values larger than 
+        ///   <see cref="float.MaxValue"/> (or smaller than <see cref="float.MinValue"/>), 
+        ///   instead <see langword="true"/> is returned and <see cref="float.PositiveInfinity"/> (or 
+        ///   <see cref="float.NegativeInfinity"/>) is emitted. 
+        /// </remarks> 
         public double GetDouble() => double.Parse(_value);
 
         /// <summary>
@@ -308,6 +321,12 @@ public class JsonNumber : JsonNode, IEquatable<JsonNumber>
         ///  <see langword="true"/> if instance was converted successfully; 
         ///  otherwise, <see langword="false"/>
         /// </returns>
+        /// <remarks> 
+        ///   On .NET Core this method does not return <see langword="false"/> for values larger than 
+        ///   <see cref="float.MaxValue"/> (or smaller than <see cref="float.MinValue"/>), 
+        ///   instead <see langword="true"/> is returned and <see cref="float.PositiveInfinity"/> (or 
+        ///   <see cref="float.NegativeInfinity"/>) is emitted. 
+        /// </remarks> 
         public bool TryGetSingle(out float value) => float.TryParse(_value, out value);
 
         /// <summary>
@@ -322,6 +341,12 @@ public class JsonNumber : JsonNode, IEquatable<JsonNumber>
         ///  <see langword="true"/> if instance was converted successfully; 
         ///  otherwise, <see langword="false"/>
         /// </returns>
+        /// <remarks> 
+        ///   On .NET Core this method does not return <see langword="false"/> for values larger than 
+        ///   <see cref="float.MaxValue"/> (or smaller than <see cref="float.MinValue"/>), 
+        ///   instead <see langword="true"/> is returned and <see cref="float.PositiveInfinity"/> (or 
+        ///   <see cref="float.NegativeInfinity"/>) is emitted. 
+        /// </remarks> 
         public bool TryGetDouble(out double value) => double.TryParse(_value, out value);
 
         /// <summary>
@@ -408,6 +433,7 @@ public class JsonNumber : JsonNode, IEquatable<JsonNumber>
         /// <exception cref="ArgumentException">
         ///   Provided value is not in a legal JSON number format.
         /// </exception>
+        /// <remarks>Provided value is stored in the same format as passed.</remarks> 
         public void SetFormattedValue(string value)
         {
             if (string.IsNullOrEmpty(value))
@@ -587,7 +613,7 @@ public void SetFormattedValue(string value)
         ///   <see langword="true"/> if the numeric value of this instance matches <paramref name="other"/>,
         ///   <see langword="false"/> otherwise.
         /// </returns>
-        public bool Equals(JsonNumber other) => _value == other._value;
+        public bool Equals(JsonNumber other) => !(other is null) && _value == other._value;
 
         /// <summary>
         ///   Compares numeric values of two JSON numbers. 
@@ -598,7 +624,7 @@ public void SetFormattedValue(string value)
         ///   <see langword="true"/> if the numeric value of instances matches,
         ///   <see langword="false"/> otherwise.
         /// </returns>
-        public static bool operator ==(JsonNumber left, JsonNumber right) => left._value == right._value;
+        public static bool operator ==(JsonNumber left, JsonNumber right) => left?._value == right?._value;
 
         /// <summary>
         ///   Compares numeric values of two JSON numbers. 
@@ -609,6 +635,6 @@ public void SetFormattedValue(string value)
         ///   <see langword="true"/> if the numeric value of instances does not match,
         ///   <see langword="false"/> otherwise.
         /// </returns>
-        public static bool operator !=(JsonNumber left, JsonNumber right) => left._value != right._value;
+        public static bool operator !=(JsonNumber left, JsonNumber right) => left?._value != right?._value;
     }
 }

src/System.Text.Json/tests/JsonNodeTests.JsonNumber.cs

@@ -8,6 +8,41 @@ namespace System.Text.Json.Tests
 {
     public static partial class JsonNodeTests
     {
+        private delegate bool TryGetValue<T>(out T result);
+
+        private static void SimpleNumberTests<T>(
+                T value,
+                Func<JsonNumber, T> ctor,
+                Action<JsonNumber, T> setter,
+                Func<T, JsonNumber> getter, TryGetValue<T> tryGetter,
+                Func<T, JsonNumber> implicitCaster)
+        {
+            JsonNumber number = new JsonNumber();
+            setter(number, value);
+            AssertValue(value, number, getter, tryGetter);
+
+            number = ctor(value);
+            AssertValue(value, number, getter, tryGetter);
+
+            number = new JsonNumber(value.ToString());
+            AssertValue(value, number, getter, tryGetter);
+
+            number = implicitCaster(value);
+            AssertValue(value, number, getter, tryGetter);
+        }
+
+        private static void AssertValue<T>(
+                T value,
+                JsonNumber number,
+                Func<T, JsonNumber> getter,
+                TryGetValue<T> tryGetter)
+        {
+            Assert.Equal(value, getter(number));
+            Assert.True(tryGetter(number, out T result));
+            Assert.Equal(value, result);
+        }
+
+
         [Fact]
         public static void TestDefaultCtor()
         {
@@ -31,30 +66,13 @@ public static void TestDefaultCtor()
         [InlineData(byte.MaxValue)]
         public static void TestByte(byte value)
         {
-            // Default constructor:
-            var jsonNumber = new JsonNumber();
-            jsonNumber.SetByte(value);
-            Assert.Equal(value, jsonNumber.GetByte());
-            Assert.True(jsonNumber.TryGetByte(out byte result));
-            Assert.Equal(value, result);
-
-            // Numeric type constructor:
-            jsonNumber = new JsonNumber(value);
-            Assert.Equal(value, jsonNumber.GetByte());
-            Assert.True(jsonNumber.TryGetByte(out result));
-            Assert.Equal(value, result);
-
-            // Implicit cast:
-            jsonNumber = value;
-            Assert.Equal(value, jsonNumber.GetByte());
-            Assert.True(jsonNumber.TryGetByte(out result));
-            Assert.Equal(value, result);
-
-            // String constructor:
-            jsonNumber = new JsonNumber(value.ToString());
-            Assert.Equal(value, jsonNumber.GetByte());
-            Assert.True(jsonNumber.TryGetByte(out result));
-            Assert.Equal(value, result);
+            SimpleNumberTests(
+                value,
+                v => new JsonNumber(v),
+                (number, v) => number.SetInt16(v),
+                number => number.GetInt16(),
+                (number, out v) => number.TryGetValue(out v),
+                v => v);
         }
 
         [Theory]
@@ -453,6 +471,8 @@ public static void TestNullString()
 
         [Theory]
         [InlineData("0")]
+        [InlineData("1.1e1")]
+        [InlineData("0.0")]
         [InlineData("-17")]
         [InlineData("17")]
         [InlineData("3.14")]