Add test for TextureExistsRewriter

tModPorter.Tests/RewriterTests/TextureExistsTest.cs

@@ -0,0 +1,52 @@
+using System.Collections.Generic;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using tModPorter.Rewriters;
+using tModPorter.Rewriters.MemberAccessRewriters;
+using Xunit;
+
+namespace tModPorter.Tests.RewriterTests
+{
+	public class TextureExistsTest
+	{
+		[Theory]
+		[InlineData("TextureExists(\"string\")", 0)]
+		[InlineData("ModContent.TextureExists(\"string\")", 1)]
+		[InlineData("if (ModContent.TextureExists(field)) { Write(ModContent.TextureExists(field)) }", 2)]
+		public void VisitNode_ShouldMatchNodeCount(string statement, int nodeCount)
+		{
+			CreateSimpleRewriter(statement, out TextureExistsRewriter rewriter,
+				out HashSet<(BaseRewriter rewriter, SyntaxNode originalNode)> nodeSet, out CompilationUnitSyntax root);
+
+			foreach (SyntaxNode assigmentNode in root.DescendantNodes())
+				rewriter.VisitNode(assigmentNode);
+
+			Assert.Equal(nodeCount, nodeSet.Count);
+		}
+
+		[Fact]
+		public void RewriteNode_ShouldMatchTarget()
+		{
+			const string statement = "ModContent.TextureExists(\"string\")";
+			const string target = "ModContent.HasAsset(\"string\")";
+
+			CreateSimpleRewriter(statement, out TextureExistsRewriter rewriter,
+				out HashSet<(BaseRewriter rewriter, SyntaxNode originalNode)> nodeSet, out CompilationUnitSyntax root);
+
+			foreach (SyntaxNode assigmentNode in root.DescendantNodes())
+				rewriter.VisitNode(assigmentNode);
+
+			root = root.RewriteMultipleNodes(nodeSet);
+
+			Assert.Equal(target, root.ToFullString());
+		}
+
+		private static void CreateSimpleRewriter(string source, out TextureExistsRewriter rewriter,
+			out HashSet<(BaseRewriter rewriter, SyntaxNode originalNode)> nodeSet, out CompilationUnitSyntax root) {
+			Utils.CreateCSharpCompilation(source, nameof(FindTypeRewriterTest), out _, out root, out SemanticModel model);
+
+			nodeSet = new HashSet<(BaseRewriter rewriter, SyntaxNode originalNode)>();
+			rewriter = new TextureExistsRewriter(model, null, nodeSet);
+		}
+	}
+}