Merge pull request #351 from wordpress-mobile/iangmaia/prototype-load…

…-swiftlint-version-on-spm

RFC: Load SwiftLint version in the Package Description

Package.swift

@@ -1,5 +1,6 @@
 // swift-tools-version:5.5
 
+import Foundation
 import PackageDescription
 
 let package = Package(
@@ -14,7 +15,7 @@ let package = Package(
         // See https://github.com/erikdoe/ocmock/issues/500#issuecomment-1002700625
         .package(url: "https://github.com/erikdoe/ocmock", revision: "afd2c6924e8a36cb872bc475248b978f743c6050"),
         .package(url: "https://github.com/Quick/Quick", from: "6.0.0"),
-        .package(url: "https://github.com/realm/SwiftLint", from: "0.54.0")
+        .package(url: "https://github.com/realm/SwiftLint", .exactItem(loadSwiftLintVersion()))
     ],
     targets: [
         .target(
@@ -60,3 +61,25 @@ let package = Package(
         ),
     ]
 )
+
+func loadSwiftLintVersion() -> Version {
+    guard let yamlString = try? String(contentsOf: URL(fileURLWithPath: #file)
+        .deletingLastPathComponent()
+        .appendingPathComponent(".swiftlint.yml")) else {
+        fatalError("Failed to read YAML file.")
+    }
+
+    guard let versionLine = yamlString.components(separatedBy: .newlines)
+        .first(where: { $0.contains("swiftlint_version") }) else {
+        fatalError("SwiftLint version not found in YAML file.")
+    }
+
+    // Assumes the format `swiftlint_version: <version>`
+    guard let version = Version(versionLine.components(separatedBy: ":")
+        .last?
+        .trimmingCharacters(in: .whitespaces) ?? "") else {
+        fatalError("Failed to extract SwiftLint version.")
+    }
+
+    return version
+}