Merge pull request #133 from ktsu-dev/fix-blank-body

Render a body of only blank lines as an empty block

Author: matt-edmondson

CodeBlocker.Test/TemplateTests.cs

@@ -478,6 +478,67 @@ public void ABodyThatWritesNothingRendersAsAnEmptyBlock()
 		Assert.AreEqual("public virtual void Run() { }\n", Render(method));
 	}
 
+	[TestMethod]
+	[DataRow(1)]
+	[DataRow(2)]
+	public void ABodyThatWritesOnlyBlankLinesRendersAsAnEmptyBlock(int newLines)
+	{
+		// A NewLine after a loop over an empty collection used to leave "public void M() " with no
+		// body, which does not compile (CS0501).
+		MethodTemplate method = new()
+		{
+			Type = "void",
+			Name = "M",
+			Keywords = { "public" },
+			BodyFactory = codeBlocker =>
+			{
+				for (int i = 0; i < newLines; i++)
+				{
+					codeBlocker.NewLine();
+				}
+			},
+		};
+
+		Assert.AreEqual("public void M() { }\n", Render(method));
+	}
+
+	[TestMethod]
+	public void AnExpressionBodyBetweenBlankLinesStaysOnTheDeclarationLine() =>
+		Assert.AreEqual(
+			"public void Reset() => count = 0;\n",
+			Render(new MethodTemplate
+			{
+				Type = "void",
+				Name = "Reset",
+				Keywords = { "public" },
+				BodyFactory = codeBlocker =>
+				{
+					codeBlocker.NewLine();
+					codeBlocker.WriteLine("=> count = 0;");
+					codeBlocker.NewLine();
+				},
+			}));
+
+	[TestMethod]
+	public void ABlankLineInsideABracedBodyIsKept()
+	{
+		MethodTemplate method = new()
+		{
+			Type = "void",
+			Name = "Run",
+			Keywords = { "public" },
+			BodyFactory = codeBlocker =>
+			{
+				using Scope scope = new(codeBlocker);
+				codeBlocker.WriteLine("First();");
+				codeBlocker.NewLine();
+				codeBlocker.WriteLine("Second();");
+			},
+		};
+
+		Assert.AreEqual("public void Run()\n{\n\tFirst();\n\n\tSecond();\n}\n", Render(method));
+	}
+
 	[TestMethod]
 	public void AMultiLineBodyIsIndentedToWhereItIsSpliced()
 	{
@@ -568,6 +629,25 @@ public void AConstructorWithNoBaseCallIsAnEmptyBlock() =>
 			"public Widget() { }\n",
 			Render(new ConstructorTemplate { Name = "Widget", Keywords = { "public" } }));
 
+	[TestMethod]
+	[DataRow(1)]
+	[DataRow(2)]
+	public void AConstructorBodyThatWritesOnlyBlankLinesIsAnEmptyBlock(int newLines) =>
+		Assert.AreEqual(
+			"public Widget() { }\n",
+			Render(new ConstructorTemplate
+			{
+				Name = "Widget",
+				Keywords = { "public" },
+				BodyFactory = codeBlocker =>
+				{
+					for (int i = 0; i < newLines; i++)
+					{
+						codeBlocker.NewLine();
+					}
+				},
+			}));
+
 	[TestMethod]
 	public void AConstructorInitialiserIsIndentedOnItsOwnLine()
 	{

CodeBlocker/Templates/TemplateRendering.cs

@@ -223,19 +223,24 @@ internal static void WriteBody(CodeBlocker codeBlocker, Action<CodeBlocker>? bod
 		string body = RenderFragment(codeBlocker, bodyFactory);
 		string[] lines = SplitLines(codeBlocker, body);
 
+		// Blank lines carry no body of their own, so they are left out when deciding its shape. A
+		// factory that only wrote spacing, such as a NewLine after a loop over an empty collection,
+		// would otherwise leave the declaration with no body at all.
+		string[] contentLines = [.. lines.Where(line => line.Length != 0)];
+
 		// A factory that wrote nothing means "declared, but empty" — a virtual base method, or a
 		// constructor that only forwards to its base.
-		if (lines.Length == 0)
+		if (contentLines.Length == 0)
 		{
 			codeBlocker.WriteLine(" { }");
 			return;
 		}
 
-		if (lines.Length == 1)
+		if (contentLines.Length == 1)
 		{
 			// An expression body stays on the declaration line.
 			codeBlocker.Write(" ");
-			codeBlocker.WriteLine(lines[0]);
+			codeBlocker.WriteLine(contentLines[0]);
 			return;
 		}