added test case for data label

Author: Harsha-SF4223

maui/src/Charts/Series/FastLineSeries.cs

@@ -16,6 +16,7 @@ namespace Syncfusion.Maui.Toolkit.Charts
 	/// <para> <b>Data Label - </b> Data labels are used to display values related to a chart segment. To render the data labels, you need to set the <see cref="ChartSeries.ShowDataLabels"/> property as <b>true</b> in <see cref="FastLineSeries"/> class. To customize the chart data labels alignment, placement, and label styles, you need to create an instance of <see cref="CartesianDataLabelSettings"/> and set to the <see cref="CartesianSeries.DataLabelSettings"/> property.</para>
 	/// <para> <b>Animation - </b> To animate the series, set <b>True</b> to the <see cref="ChartSeries.EnableAnimation"/> property.</para>
 	/// <para> <b>LegendIcon - </b> To customize the legend icon using the <see cref="ChartSeries.LegendIcon"/> property.</para>
+	/// <para> The FastLineSeries does not support empty points.</para>
 	/// </remarks>
 	/// <example>
 	/// # [Xaml](#tab/tabid-1)

maui/tests/Syncfusion.Maui.Toolkit.UnitTest/Chart/Features/DataLabelUnitTests.cs

@@ -601,6 +601,24 @@ public void GetLabelContent_VariousInputs_ReturnsExpectedContent(double value, s
 			Assert.Equal(expectedContent, result);
 		}
 
+		[Theory]
+		[InlineData(double.NaN, "", "")]
+		[InlineData(0, "0", "")]
+		[InlineData(0, "000", "000")]
+		[InlineData(123.456, "123", "#")]
+		[InlineData(123.456, "123.46", "")]
+		[InlineData(123.456, "123.456", "#.###")]
+		[InlineData(123.0, "123", "0")]
+		public void GetLabelContent_VariousInput_ReturnsExpectedContent(double value, string expectedContent, string format)
+		{
+			var cartesianDataLabelSettings = new CartesianDataLabelSettings
+			{
+				LabelStyle = new ChartDataLabelStyle { LabelFormat = format }
+			};
+			var result = cartesianDataLabelSettings.GetLabelContent(value);
+			Assert.Equal(expectedContent, result);
+		}
+
 		[Fact]
 		public void GetDefaultTextColor_ReturnsExpectedColor()
 		{