Tests: Migrate PackageCommandTests to Swift Testing and Augment

Migrate the `PackageCommandTests` to Swift Testing and augment the suite
to run against the Native and SwiftBuild build system, in addition to
the `debug` and `release` build configurations.

Relates to: #8997
issue: rdar://157669245

Author: bkhouri

.gitignore

@@ -1,4 +1,5 @@
 .build
+.test
 .index-build
 DerivedData
 /.previous-build

Fixtures/Miscellaneous/Plugins/BuildToolPluginCompilationError/Package.swift

@@ -0,0 +1,17 @@
+// swift-tools-version: 5.6
+import PackageDescription
+let package = Package(
+    name: "MyPackage",
+    targets: [
+        .target(
+            name: "MyLibrary",
+            plugins: [
+                "MyPlugin",
+            ]
+        ),
+        .plugin(
+            name: "MyPlugin",
+            capability: .buildTool()
+        ),
+    ]
+)

Fixtures/Miscellaneous/Plugins/BuildToolPluginCompilationError/Plugins/MyPlugin/plugin.swift

@@ -0,0 +1,15 @@
+import PackagePlugin
+import Foundation
+@main
+struct MyBuildToolPlugin: BuildToolPlugin {
+    func createBuildCommands(
+        context: PluginContext,
+        target: Target
+    ) throws -> [Command] {
+        print("This is text from the plugin")
+        throw "This is an error from the plugin"
+        return []
+    }
+
+}
+extension String : Error {}

Fixtures/Miscellaneous/Plugins/BuildToolPluginCompilationError/Sources/MyLibrary/library.swift

@@ -0,0 +1 @@
+public func Foo() { }

Fixtures/Miscellaneous/Plugins/CommandPluginCompilationError/Package.swift

@@ -0,0 +1,34 @@
+// swift-tools-version: 5.6
+import PackageDescription
+let package = Package(
+    name: "MyPackage",
+    products: [
+        .library(
+            name: "MyLibrary",
+            targets: ["MyLibrary"]
+        ),
+        .executable(
+            name: "MyExecutable",
+            targets: ["MyExecutable"]
+        ),
+    ],
+    targets: [
+        .target(
+            name: "MyLibrary"
+        ),
+        .executableTarget(
+            name: "MyExecutable",
+            dependencies: ["MyLibrary"]
+        ),
+        .plugin(
+            name: "MyBuildToolPlugin",
+            capability: .buildTool()
+        ),
+        .plugin(
+            name: "MyCommandPlugin",
+            capability: .command(
+                intent: .custom(verb: "my-build-tester", description: "Help description")
+            )
+        ),
+    ]
+)

Fixtures/Miscellaneous/Plugins/CommandPluginCompilationError/Plugins/MyBuildToolPlugin/plugin.swift

@@ -0,0 +1,9 @@
+import PackagePlugin
+@main struct MyBuildToolPlugin: BuildToolPlugin {
+    func createBuildCommands(
+        context: PluginContext,
+        target: Target
+    ) throws -> [Command] {
+        return []
+    }
+}

Fixtures/Miscellaneous/Plugins/CommandPluginCompilationError/Plugins/MyCommandPlugin/plugin.swift

@@ -0,0 +1,9 @@
+import PackagePlugin
+@main struct MyCommandPlugin: CommandPlugin {
+    func performCommand(
+        context: PluginContext,
+        arguments: [String]
+    ) throws {
+        this is an error
+    }
+}

Fixtures/Miscellaneous/Plugins/CommandPluginCompilationError/Sources/MyExecutable/main.swift

@@ -0,0 +1,2 @@
+import MyLibrary
+print("\\(GetGreeting()), World!")

Fixtures/Miscellaneous/Plugins/CommandPluginCompilationError/Sources/MyLibrary/library.swift

@@ -0,0 +1 @@
+public func GetGreeting() -> String { return "Hello" }

Sources/PackageModel/Toolchain+SupportedFeatures.swift

@@ -70,7 +70,7 @@ public enum SwiftCompilerFeature {
 }
 
 extension Toolchain {
-    public var supportesSupportedFeatures: Bool {
+    public var supportsSupportedFeatures: Bool {
         guard let features = try? swiftCompilerSupportedFeatures else {
             return false
         }