feat: work on day 11 part 1

11/PlutonianPebbles.Tests/ObserverTests.cs

@@ -0,0 +1,25 @@
+namespace PlutonianPebbles.Tests;
+
+public class ObserverTests
+{
+  private static readonly string[] ExampleInput = ["125", "17"];
+  
+  [Test]
+  [MethodDataSource(nameof(BlinkTestCases))]
+  public async Task Blink_WhenCalled_ItShouldReturnExpectedValue(BlinkTestCase testCase)
+  {
+    var stones = testCase.Stones.Select(Stone.From).ToList();
+    var observer = Observer.Of(stones);
+
+    var result = observer.Blink(testCase.NumberOfBlinks);
+
+    await Assert.That(result).IsEqualTo(testCase.ExpectedLineOfStones);
+  }
+
+  public static IEnumerable<Func<BlinkTestCase>> BlinkTestCases()
+  {
+    yield return () => new(ExampleInput, 0, "125 17");
+  }
+
+  public record BlinkTestCase(string[] Stones, int NumberOfBlinks, string ExpectedLineOfStones);
+}