Add inlineHTML method. (#200)

Sources/Slipstream/Rendering/Render.swift

@@ -28,3 +28,23 @@ public func renderHTML(_ view: any View) throws -> String {
   try view.render(document, environment: EnvironmentValues())
   return try document.html()
 }
+
+/// Renders the given view as an HTML document and returns the HTML.
+///
+/// This is a non-throwing alternative to ``renderHTML(_:)`` that can be used more easily in
+/// string concatenation, such as ``MarkdownText`` content.
+///
+/// Note that this method creates a new environment context.
+///
+/// - Parameter builder: A block that constructs the view or set of views to be rendered.
+/// - Returns: The generated and formatted HTML string. If an error occurs during rendering, then the
+/// error will be returned as an HTML comment.
+public func inlineHTML<Content: View>(@ViewBuilder _ builder: () -> Content) -> String {
+  let document = Document("/")
+  do {
+    try builder().render(document, environment: EnvironmentValues())
+    return try document.html()
+  } catch let error {
+    return "<!-- \(error) -->"
+  }
+}

Tests/SlipstreamTests/Rendering/InlineHTMLTests.swift

@@ -0,0 +1,21 @@
+import Foundation
+import Testing
+
+import Slipstream
+
+final class InlineHTMLTests {
+
+  @Test func stringConcatenation() async throws {
+    #expect("""
+This is some text.
+
+\(inlineHTML {
+  Text("Foo")
+})
+""" == """
+This is some text.
+
+<p>Foo</p>
+""")
+  }
+}