Stop using XCTest in MMIOFileCheckTests (#138)

Replaces XCTest with Swift-Testing and drops direct use of Dispatch in
MMIOFileCheckTests. This hopefully resolves whatever issue was causing
Dispatch to crash.

.github/workflows/swift.yml

@@ -33,8 +33,8 @@ jobs:
           - name: jammy
             version: "22.04"
         swift:
-          - repo: swift
-            version: "6.0"
+          - repo: swiftlang/swift
+            version: "nightly-6.1"
           - repo: swiftlang/swift
             version: "nightly-main"
     container: ${{ matrix.swift.repo }}:${{ matrix.swift.version }}-${{ matrix.os.name }}

Sources/MMIOUtilities/ShellCommand.swift

@@ -53,7 +53,7 @@ public func sh(
   _ command: String,
   collectStandardOutput: Bool = true,
   collectStandardError: Bool = true
-) throws -> String {
+) throws(ShellCommandError) -> String {
   let process = Process()
   process.executableURL = URL(fileURLWithPath: "/bin/sh")
   process.arguments = ["-c", "export PATH=$PATH:~/bin; \(command)"]

Tests/MMIOFileCheckTests/FileCheck/SimpleFileCheck.swift

@@ -16,18 +16,18 @@ import MMIOUtilities
 ///
 /// SimpleFileCheck is not intended for general use.
 struct SimpleFileCheck {
-  var inputFileURL: URL
-  var outputFileURL: URL
+  var inputFile: URL
+  var outputFile: URL
 }
 
 extension SimpleFileCheck {
   func run() -> [LLVMDiagnostic] {
     // Load the input file and split it into lines. If we can't load the file,
     // return and report diagnostics.
-    let inputPath = self.inputFileURL.path
+    let inputPath = self.inputFile.path
     let input: String
     do {
-      input = try String(contentsOf: self.inputFileURL, encoding: .utf8)
+      input = try String(contentsOf: self.inputFile, encoding: .utf8)
     } catch {
       return [.failedToLoadFile(at: inputPath, error: error)]
     }
@@ -37,10 +37,10 @@ extension SimpleFileCheck {
 
     // Load the output file and split it into lines. If we can't load the file,
     // return and report diagnostics.
-    let outputPath = self.outputFileURL.path
+    let outputPath = self.outputFile.path
     let output: String
     do {
-      output = try String(contentsOf: self.outputFileURL, encoding: .utf8)
+      output = try String(contentsOf: self.outputFile, encoding: .utf8)
     } catch {
       return [.failedToLoadFile(at: outputPath, error: error)]
     }