Clean up Widgets

* Move /Widgets/Live/* to /Live/*
* Move /Widgets/Prompt/* to /Prompts/*
* Move tests and expectations to match the new locations

test/Spectre.Console.Tests/Unit/Widgets/TreeTests.cs

@@ -0,0 +1,85 @@
+using System.Linq;
+using System.Threading.Tasks;
+using Shouldly;
+using Spectre.Console.Testing;
+using Spectre.Verify.Extensions;
+using VerifyXunit;
+using Xunit;
+
+namespace Spectre.Console.Tests.Unit
+{
+    [UsesVerify]
+    [ExpectationPath("Widgets/Tree")]
+    public class TreeTests
+    {
+        [Fact]
+        [Expectation("Render")]
+        public Task Should_Render_Tree_Correctly()
+        {
+            // Given
+            var console = new TestConsole();
+
+            var tree = new Tree(new Text("Root node")).Guide(TreeGuide.DoubleLine);
+
+            var nestedChildren = Enumerable.Range(0, 10).Select(x => new Text($"multiple\nline {x}"));
+            var child2 = new TreeNode(new Text("child2"));
+            var child2Child = new TreeNode(new Text("child2-1"));
+            child2.AddNode(child2Child);
+            child2Child.AddNode(new TreeNode(new Text("Child2-1-1\nchild")));
+            var child3 = new TreeNode(new Text("child3"));
+            var child3Child = new TreeNode(new Text("single leaf\nmultiline"));
+            child3Child.AddNode(new TreeNode(new Calendar(2021, 01)));
+            child3.AddNode(child3Child);
+
+            tree.AddNode("child1").AddNodes(nestedChildren);
+            tree.AddNode(child2);
+            tree.AddNode(child3);
+            tree.AddNode("child4");
+
+            // When
+            console.Write(tree);
+
+            // Then
+            return Verifier.Verify(console.Output);
+        }
+
+        [Fact]
+        [Expectation("Render_NoChildren")]
+        public Task Should_Render_Tree_With_No_Child_Nodes_Correctly()
+        {
+            // Given
+            var console = new TestConsole();
+            var tree = new Tree(new Text("Root node"));
+
+            // When
+            console.Write(tree);
+
+            // Then
+            return Verifier.Verify(console.Output);
+        }
+
+        [Fact]
+        public void Should_Throw_If_Tree_Contains_Cycles()
+        {
+            // Given
+            var console = new TestConsole();
+
+            var child2 = new TreeNode(new Text("child 2"));
+            var child3 = new TreeNode(new Text("child 3"));
+            var child1 = new TreeNode(new Text("child 1"));
+            child1.AddNodes(child2, child3);
+            var root = new TreeNode(new Text("Branch Node"));
+            root.AddNodes(child1);
+            child2.AddNode(root);
+
+            var tree = new Tree("root node");
+            tree.AddNodes(root);
+
+            // When
+            var result = Record.Exception(() => console.Write(tree));
+
+            // Then
+            result.ShouldBeOfType<CircularTreeException>();
+        }
+    }
+}