test: consolidate, standardize and improve test suite

- Remove unused Moq package reference
- Fix blank lines between [TestMethod] and public void (artifacts of previously removed [TestCategory] attributes) in ExceptionGuardTests, PolylineEncodingTests, CoordinateDeltaTests, Pow10Tests
- Consolidate Pow10Tests: 13 individual tests -> 2 data-driven [DataRow] methods
- Consolidate CoordinateDeltaTests: 8+ repeated Next/ToString tests -> 3 DataRow methods covering all input combinations
- Consolidate PolylineEncodingTests (1424 -> 681 lines): Normalize non-finite, Normalize value, Denormalize value, GetRequiredBufferSize, ValidateCharRange, ValidateBlockLength all converted to [DataRow]
- Add XML doc comments to LogDebugExtensionsTests and LogWarningExtensionsTests methods
- Rewrite AbstractPolylineDecoderTests: add copyright header, file-scoped namespace, XML docs, explicit types
- Add using System.Globalization to CoordinateDeltaTests

Agent-Logs-Url: https://github.com/petesramek/polyline-algorithm-csharp/sessions/2ffb0731-b271-46b2-8126-78f2f97d1f21

Co-authored-by: petesramek <2333452+petesramek@users.noreply.github.com>

Author: Copilot

tests/PolylineAlgorithm.Tests/Abstraction/AbstractPolylineDecoderTests.cs

@@ -1,39 +1,59 @@
+//
+// Copyright © Pete Sramek. All rights reserved.
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+//
+
+namespace PolylineAlgorithm.Tests.Abstraction;
+
 using PolylineAlgorithm.Abstraction;
+using System;
+using System.Collections.Generic;
+
+/// <summary>
+/// Tests for <see cref="AbstractPolylineDecoder{TPolyline, TCoordinate}"/>.
+/// </summary>
+[TestClass]
+public sealed class AbstractPolylineDecoderTests {
+    private sealed class TestStringDecoder : AbstractPolylineDecoder<string, (double Latitude, double Longitude)> {
+        protected override ReadOnlyMemory<char> GetReadOnlyMemory(in string polyline) => polyline.AsMemory();
+        protected override (double Latitude, double Longitude) CreateCoordinate(double latitude, double longitude) => (latitude, longitude);
+    }
+
+    /// <summary>
+    /// Tests that Decode with a null polyline throws <see cref="ArgumentNullException"/>.
+    /// </summary>
+    [TestMethod]
+    public void Decode_With_Null_Polyline_Throws_ArgumentNullException() {
+        // Arrange
+        TestStringDecoder decoder = new();
+
+        // Act & Assert
+        ArgumentNullException ex = Assert.ThrowsExactly<ArgumentNullException>(() => decoder.Decode((string?)null!).ToList());
+        Assert.AreEqual("polyline", ex.ParamName);
+    }
+
+    /// <summary>
+    /// Tests that Decode with an empty polyline throws <see cref="InvalidPolylineException"/>.
+    /// </summary>
+    [TestMethod]
+    public void Decode_With_Empty_Polyline_Throws_InvalidPolylineException() {
+        // Arrange
+        TestStringDecoder decoder = new();
+
+        // Act & Assert
+        Assert.ThrowsExactly<InvalidPolylineException>(() => decoder.Decode(string.Empty).ToList());
+    }
+
+    /// <summary>
+    /// Tests that Decode with a polyline containing an invalid character throws <see cref="InvalidPolylineException"/>.
+    /// </summary>
+    [TestMethod]
+    public void Decode_With_Invalid_Character_Polyline_Throws_InvalidPolylineException() {
+        // Arrange
+        TestStringDecoder decoder = new();
 
-namespace PolylineAlgorithm.Tests.Abstraction {
-    [TestClass]
-    public sealed class AbstractPolylineDecoderTests {
-        private sealed class TestStringDecoder : AbstractPolylineDecoder<string, (double Latitude, double Longitude)> {
-            protected override ReadOnlyMemory<char> GetReadOnlyMemory(in string polyline) => polyline.AsMemory();
-            protected override (double Latitude, double Longitude) CreateCoordinate(double latitude, double longitude) => (latitude, longitude);
-        }
-
-        [TestMethod]
-        public void Decode_Null_Polyline_Throws_ArgumentNullException() {
-            // Arrange
-            var decoder = new TestStringDecoder();
-
-            // Act & Assert
-            var ex = Assert.ThrowsExactly<ArgumentNullException>(() => decoder.Decode((string?)null!).ToList());
-            Assert.AreEqual("polyline", ex.ParamName);
-        }
-
-        [TestMethod]
-        public void Decode_Empty_Polyline_Throws_InvalidPolylineException() {
-            // Arrange
-            var decoder = new TestStringDecoder();
-
-            // Act & Assert - empty string is too short (min block length = 1)
-            Assert.ThrowsExactly<InvalidPolylineException>(() => decoder.Decode(string.Empty).ToList());
-        }
-
-        [TestMethod]
-        public void Decode_Invalid_Character_Polyline_Throws_InvalidPolylineException() {
-            // Arrange
-            var decoder = new TestStringDecoder();
-
-            // '!' (33) is below allowed range ('?' == 63) and should trigger invalid polyline character
-            Assert.ThrowsExactly<InvalidPolylineException>(() => decoder.Decode("!").ToList());
-        }
+        // '!' (33) is below allowed range ('?' == 63)
+        // Act & Assert
+        Assert.ThrowsExactly<InvalidPolylineException>(() => decoder.Decode("!").ToList());
     }
-}
+}