Interpret issue/pr links like GitHub does in markdown

Lambdas/GHHooks/Extensions/String+Document.swift

@@ -15,8 +15,23 @@ extension String {
         assert(hardLimit > 0, "Hard length limit must be greater than zero (got \(hardLimit)).")
         assert(hardLimit >= maxVisualLength, "maxVisualLength '\(maxVisualLength)' can't be more than hardLimit '\(hardLimit)'.")
 
+        /// Interpret urls like GitHub does.
+        /// For example GitHub changes `https://github.com/vapor/penny-bot/issues/99` to
+        /// `[vapor/penny-bot#99](https://github.com/vapor/penny-bot/issues/99)` which
+        /// ends up looking like a blue `vapor/penny-bot#99` text linked to the url.
+        let regex = #/
+            https://(?:www\.)?github\.com
+            /(?<org>[A-Za-z0-9](?:[A-Za-z0-9\-]*[A-Za-z0-9])?)
+            /(?<repo>[A-Za-z0-9.\-_]+)
+            /(?:pull|issues)
+            /(?<number>\d+)
+        /#
+        let withModifiedLinks = self.replacing(regex) { match in
+            "[\(match.output.org)/\(match.output.repo)#\(match.output.number)](\(self[match.range]))"
+        }
+
         /// Remove all HTML elements and all links lacking a destination; they don't look good in Discord.
-        let document1 = Document(parsing: self)
+        let document1 = Document(parsing: withModifiedLinks)
         var htmlRemover = HTMLAndImageRemover()
         guard let markup1 = htmlRemover.visit(document1) else { return "" }
         var emptyLinksRemover = EmptyLinksRemover()

Tests/PennyTests/Tests/+XCTest.swift

@@ -28,8 +28,8 @@ extension XCTestCase {
                         XCTFail(
                             """
                             Not equal at line \(idx + 1):
-                            Expected: \(line1.debugDescription)
-                            Got:      \(line2.debugDescription)
+                            Got:      \(line1.debugDescription)
+                            Expected: \(line2.debugDescription)
                             """,
                             file: file,
                             line: line

Tests/PennyTests/Tests/GHHooksTests.swift

@@ -502,6 +502,27 @@ class GHHooksTests: XCTestCase {
             There should be no more `Sendable` warnings in Vapor, even with complete concurrency checking turned on.
             """)
         }
+
+        /// Test modifying GitHub links
+        do {
+            let text = """
+            Final stage of Vapor’s `Sendable` journey as `Request` is now `Sendable` at https://github.com/swift-server/swiftly/pull/9.
+
+            There should https://github.com/vapor-bad-link/issues/44 be no more `Sendable` warnings in Vaporhttps://github.com/vapor/penny-bot/issues/98, even with complete concurrency checking turned on.
+            """
+
+            let formatted = text.formatMarkdown(
+                maxVisualLength: 512,
+                hardLimit: 2_048,
+                trailingTextMinLength: 128
+            )
+
+            XCTAssertMultilineStringsEqual(formatted, """
+            Final stage of Vapor’s `Sendable` journey as `Request` is now `Sendable` at [swift-server/swiftly#9](https://github.com/swift-server/swiftly/pull/9).
+
+            There should https://github.com/vapor-bad-link/issues/44 be no more `Sendable` warnings in Vapor[vapor/penny-bot#98](https://github.com/vapor/penny-bot/issues/98), even with complete concurrency checking turned on.
+            """)
+        }
     }
 
     func testHeadingFinder() async throws {