Ignore exit code when checking for system-level packages

FreeBSD's pkg returns 1 if a package isn't installed. Across all platforms, we really only care about parsing the tool's output, not whether it exited successfully or not. This allows tests to be properly skipped on FreeBSD when the requisite tool is not installed.

Author: jakepetroules

Sources/SWBTestSupport/SkippedTestSupport.swift

@@ -217,10 +217,17 @@ extension Trait where Self == Testing.ConditionTrait {
                 }
             }
 
+            func runProcessIgnoringExitCode(_ args: [String]) async throws -> String {
+                guard let first = args.first else {
+                    throw StubError.error("Invalid number of arguments")
+                }
+                return try await String(decoding: Process.getOutput(url: URL(filePath: first), arguments: Array(args.dropFirst())).stdout, as: UTF8.self)
+            }
+
             func checkInstalled(hostOS: OperatingSystem, packageManagerPath: Path, args: [String], packages: [String], regex: Regex<(Substring, name: Substring)>) async throws -> Bool {
                 if try ProcessInfo.processInfo.hostOperatingSystem() == hostOS && localFS.exists(packageManagerPath) {
                     var installedPackages: Set<String> = []
-                    for line in try await runProcess([packageManagerPath.str] + args + (packageManagerPath.basenameWithoutSuffix == "pkg_info" ? [] : packages)).split(separator: "\n") {
+                    for line in try await runProcessIgnoringExitCode([packageManagerPath.str] + args + (packageManagerPath.basenameWithoutSuffix == "pkg_info" ? [] : packages)).split(separator: "\n") {
                         if let packageName = try regex.firstMatch(in: line)?.output.name {
                             installedPackages.insert(String(packageName))
                         }