Adds null/empty checks to date math parsing

Ensures that the `DateMath.Parse` and `TimeUnit.Parse` methods handle null or empty expressions gracefully by throwing `ArgumentException` or `ArgumentNullException` as appropriate. This prevents unexpected behavior and improves the robustness of the date parsing logic. Also updates `TryParse` methods to accept nullable string parameters.

Author: niemyjski

src/Exceptionless.DateTimeExtensions/DateMath.cs

@@ -49,6 +49,8 @@ public static partial class DateMath
     /// <exception cref="ArgumentException">Thrown when the expression is invalid or cannot be parsed</exception>
     public static DateTimeOffset Parse(string expression, DateTimeOffset relativeBaseTime, bool isUpperLimit = false)
     {
+        ArgumentException.ThrowIfNullOrEmpty(expression);
+
         if (!TryParse(expression, relativeBaseTime, isUpperLimit, out DateTimeOffset result))
             throw new ArgumentException($"Invalid date math expression: {expression}", nameof(expression));
 
@@ -63,7 +65,7 @@ public static DateTimeOffset Parse(string expression, DateTimeOffset relativeBas
     /// <param name="isUpperLimit">Whether this is for an upper limit (affects rounding behavior)</param>
     /// <param name="result">The parsed DateTimeOffset if successful</param>
     /// <returns>True if parsing succeeded, false otherwise</returns>
-    public static bool TryParse(string expression, DateTimeOffset relativeBaseTime, bool isUpperLimit, out DateTimeOffset result)
+    public static bool TryParse(string? expression, DateTimeOffset relativeBaseTime, bool isUpperLimit, out DateTimeOffset result)
     {
         result = default;
 
@@ -90,6 +92,7 @@ public static bool TryParse(string expression, DateTimeOffset relativeBaseTime,
     /// <exception cref="ArgumentNullException">Thrown when timeZone is null</exception>
     public static DateTimeOffset Parse(string expression, TimeZoneInfo timeZone, bool isUpperLimit = false)
     {
+        ArgumentException.ThrowIfNullOrEmpty(expression);
         ArgumentNullException.ThrowIfNull(timeZone);
 
         if (!TryParse(expression, timeZone, isUpperLimit, out DateTimeOffset result))
@@ -107,7 +110,7 @@ public static DateTimeOffset Parse(string expression, TimeZoneInfo timeZone, boo
     /// <param name="result">The parsed DateTimeOffset if successful</param>
     /// <returns>True if parsing succeeded, false otherwise</returns>
     /// <exception cref="ArgumentNullException">Thrown when timeZone is null</exception>
-    public static bool TryParse(string expression, TimeZoneInfo timeZone, bool isUpperLimit, out DateTimeOffset result)
+    public static bool TryParse(string? expression, TimeZoneInfo timeZone, bool isUpperLimit, out DateTimeOffset result)
     {
         ArgumentNullException.ThrowIfNull(timeZone);
 
@@ -216,7 +219,7 @@ public static bool TryParseFromMatch(Match match, TimeZoneInfo timeZone, bool is
     /// </summary>
     /// <param name="expression">The expression to validate</param>
     /// <returns>True if the expression is valid date math, false otherwise</returns>
-    public static bool IsValidExpression(string expression)
+    public static bool IsValidExpression(string? expression)
     {
         if (String.IsNullOrEmpty(expression))
             return false;

src/Exceptionless.DateTimeExtensions/DateTimeRange.cs

@@ -123,7 +123,7 @@ public static IReadOnlyList<IPartParser> PartParsers
     /// Parses the date range from the passed in content.
     /// </summary>
     /// <param name="content">String date range</param>
-    public static DateTimeRange Parse(string content)
+    public static DateTimeRange Parse(string? content)
     {
         return Parse(content, DateTimeOffset.Now);
     }
@@ -133,7 +133,7 @@ public static DateTimeRange Parse(string content)
     /// </summary>
     /// <param name="content">String date range</param>
     /// <param name="relativeBaseTime">Relative dates will be base on this time.</param>
-    public static DateTimeRange Parse(string content, DateTimeOffset relativeBaseTime)
+    public static DateTimeRange Parse(string? content, DateTimeOffset relativeBaseTime)
     {
         if (String.IsNullOrEmpty(content))
             return Empty;

src/Exceptionless.DateTimeExtensions/TimeUnit.cs

@@ -4,8 +4,7 @@ public static class TimeUnit
 {
     public static TimeSpan Parse(string value)
     {
-        if (String.IsNullOrEmpty(value))
-            throw new ArgumentNullException(nameof(value));
+        ArgumentException.ThrowIfNullOrEmpty(value);
 
         var time = ParseTime(value);
         if (time.HasValue)
@@ -14,7 +13,7 @@ public static TimeSpan Parse(string value)
         throw new ArgumentException($"Unable to parse value '{value}' as a valid time value.");
     }
 
-    public static bool TryParse(string value, out TimeSpan? time)
+    public static bool TryParse(string? value, out TimeSpan? time)
     {
         time = null;
         if (String.IsNullOrEmpty(value))

tests/Exceptionless.DateTimeExtensions.Tests/DateMathTests.cs

@@ -305,7 +305,6 @@ public void Parse_ExplicitDateWithOperations_ReturnsCorrectResult(string express
     }
 
     [Theory]
-    [InlineData("")]
     [InlineData("   ")]
     [InlineData("invalid")]
     [InlineData("now+1x")] // Invalid unit
@@ -332,13 +331,19 @@ public void Parse_InvalidExpressions_ThrowsArgumentException(string expression)
     }
 
     [Fact]
-    public void Parse_NullExpression_ThrowsArgumentException()
+    public void Parse_NullExpression_ThrowsArgumentNullException()
     {
-        _logger.LogDebug("Testing Parse with null expression, expecting ArgumentException");
+        _logger.LogDebug("Testing Parse with null expression, expecting ArgumentNullException");
 
-        var exception = Assert.Throws<ArgumentException>(() => DateMath.Parse(null!, _baseTime));
+        Assert.Throws<ArgumentNullException>(() => DateMath.Parse(null!, _baseTime));
+    }
 
-        _logger.LogDebug("Exception thrown as expected: {Message}", exception.Message);
+    [Fact]
+    public void Parse_EmptyExpression_ThrowsArgumentException()
+    {
+        _logger.LogDebug("Testing Parse with empty expression, expecting ArgumentException");
+
+        Assert.Throws<ArgumentException>(() => DateMath.Parse("", _baseTime));
     }
 
     [Theory]