Adjust for when key is possibly null due to ViewBag

Author: Joshua-Lester3

EssentialCSharp.Web.Tests/SiteMappingTests.cs

@@ -85,18 +85,16 @@ public void FindPercentComplete_KeyIsNull_ThrowsArgumentNullException()
         // Arrange
 
         // Act
+        string? percent = GetSiteMap().FindPercentComplete(null!);
 
         // Assert
-        Assert.Throws<ArgumentNullException>(() =>
-        {
-            GetSiteMap().FindPercentComplete(null!);
-        });
+        Assert.Null(percent);
     }
 
     [Theory]
     [InlineData("   ")]
     [InlineData("")]
-    public void FindPercentComplete_KeyIsWhiteSpace_ThrowsArgumentException(string key)
+    public void FindPercentComplete_KeyIsWhiteSpace_ThrowsArgumentException(string? key)
     {
         // Arrange
 
@@ -112,12 +110,12 @@ public void FindPercentComplete_KeyIsWhiteSpace_ThrowsArgumentException(string k
     [Theory]
     [InlineData("hello-world", "50.00")]
     [InlineData("c-syntax-fundamentals", "100.00")]
-    public void FindPercentComplete_ValidKey_Success(string key, string result)
+    public void FindPercentComplete_ValidKey_Success(string? key, string result)
     {
         // Arrange
 
         // Act
-        string percent = GetSiteMap().FindPercentComplete(key);
+        string? percent = GetSiteMap().FindPercentComplete(key);
 
         // Assert
         Assert.Equal(result, percent);
@@ -130,7 +128,7 @@ public void FindPercentComplete_EmptySiteMappings_ReturnsZeroPercent()
         IList<SiteMapping> siteMappings = new List<SiteMapping>();
 
         // Act
-        string percent = siteMappings.FindPercentComplete("test");
+        string? percent = siteMappings.FindPercentComplete("test");
 
         // Assert
         Assert.Equal("0.00", percent);

EssentialCSharp.Web/Extensions/SiteMappingListExtensions.cs

@@ -32,9 +32,16 @@ public static class SiteMappingListExtensions
     /// <param name="siteMappings">IList of SiteMappings</param>
     /// <param name="key">If null, uses the first key in the list</param>
     /// <returns>Returns a formatted double for use as the percent complete.</returns>
-    public static string FindPercentComplete(this IList<SiteMapping> siteMappings, string key)
+    public static string? FindPercentComplete(this IList<SiteMapping> siteMappings, string? key)
     {
-        ArgumentNullException.ThrowIfNullOrWhiteSpace(key);
+        if (key is null)
+        {
+            return null;
+        }
+        if (key.Trim().Length is 0)
+        {
+            throw new ArgumentException("Parameter key is whitespace or empty: ", nameof(key));
+        }
         int currentMappingCount = 0;
         int overallMappingCount = 0;
         bool currentPageFound = false;