Add wasmtime as a default WASI runtime

.github/workflows/swift.yml

@@ -37,9 +37,9 @@ jobs:
 
       - name: Install dependencies for Ubuntu
         if: startsWith(matrix.os, 'ubuntu')
-        run: |
-          sudo apt-get install wabt -y
-          curl https://get.wasmer.io -sSfL | sh
+        run: sudo apt-get install wabt -y
+
+      - uses: bytecodealliance/actions/wasmtime/setup@v1
 
       - name: Build the project
         run: |
@@ -55,11 +55,6 @@ jobs:
           cp -r static $HOME/.carton
 
       - name: Run Tests
-        run: |
-          set -ex
-          if [ -e /home/runner/.wasmer/wasmer.sh ]; then
-            source /home/runner/.wasmer/wasmer.sh
-          fi
-          swift test
+        run: swift test
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

Brewfile

@@ -1,5 +1,4 @@
 brew "pre-commit"
 brew "swiftformat"
 brew "binaryen"
-brew "wasmer"
 brew "wabt"

Sources/CartonCLI/Commands/TestRunners/CommandTestRunner.swift

@@ -16,14 +16,22 @@ import CartonHelpers
 import CartonKit
 import Foundation
 
+struct CommandTestRunnerError: Error, CustomStringConvertible {
+  let description: String
+
+  init(_ description: String) {
+    self.description = description
+  }
+}
+
 struct CommandTestRunner: TestRunner {
   let testFilePath: AbsolutePath
   let listTestCases: Bool
   let testCases: [String]
   let terminal: InteractiveWriter
 
   func run() async throws {
-    let program = ProcessInfo.processInfo.environment["CARTON_TEST_RUNNER"] ?? "wasmer"
+    let program = try ProcessInfo.processInfo.environment["CARTON_TEST_RUNNER"] ?? defaultWASIRuntime()
     terminal.write("\nRunning the test bundle with \"\(program)\":\n", inColor: .yellow)
     var arguments = [program, testFilePath.pathString]
     if listTestCases {
@@ -35,4 +43,11 @@ struct CommandTestRunner: TestRunner {
     try await Process.run(arguments, parser: TestsParser(), terminal)
   }
 
+  func defaultWASIRuntime() throws -> String {
+    let candidates = ["wasmtime", "wasmer"]
+    guard let found = candidates.lazy.compactMap({ Process.findExecutable($0) }).first else {
+      throw CommandTestRunnerError("No WASI runtime found. Please install one of the following: \(candidates.joined(separator: ", "))")
+    }
+    return found.pathString
+  }
 }