"swiftly uninstall all" command to remove all installed toolchains

Sources/Swiftly/Uninstall.swift

@@ -33,6 +33,10 @@ struct Uninstall: SwiftlyCommand {
         The latest installed stable release can be uninstalled by specifying  'latest':
 
             $ swiftly uninstall latest
+
+        Finally, all installed toolchains can be uninstalled by specifying 'all':
+
+            $ swiftly uninstall all
         """
     ))
     var toolchain: String
@@ -44,9 +48,19 @@ struct Uninstall: SwiftlyCommand {
     var assumeYes: Bool = false
 
     mutating func run() async throws {
-        let selector = try ToolchainSelector(parsing: self.toolchain)
         let startingConfig = try Config.load()
-        let toolchains = startingConfig.listInstalledToolchains(selector: selector)
+
+        let toolchains: [ToolchainVersion]
+        if self.toolchain == "all" {
+            // Sort the uninstalled toolchains such that the in-use toolchain will be uninstalled last.
+            // This avoids printing any unnecessary output from using new toolchains while the uninstall is in progress.
+            toolchains = startingConfig.listInstalledToolchains(selector: nil).sorted { a, b in
+                a != startingConfig.inUse && (b == startingConfig.inUse || a < b)
+            }
+        } else {
+            let selector = try ToolchainSelector(parsing: self.toolchain)
+            toolchains = startingConfig.listInstalledToolchains(selector: selector)
+        }
 
         guard !toolchains.isEmpty else {
             SwiftlyCore.print("No toolchains matched \"\(self.toolchain)\"")

Tests/SwiftlyTests/UninstallTests.swift

@@ -283,4 +283,17 @@ final class UninstallTests: SwiftlyTests {
             )
         }
     }
+
+    /// Tests that providing "all" as an argument to uninstall will uninstall all toolchains.
+    func testUninstallAll() async throws {
+        let toolchains = Set([Self.oldStable, Self.newStable, Self.newMainSnapshot, Self.oldReleaseSnapshot])
+        try await self.withMockedHome(homeName: Self.homeName, toolchains: toolchains, inUse: Self.newMainSnapshot) {
+            var uninstall = try self.parseCommand(Uninstall.self, ["uninstall", "-y", "all"])
+            _ = try await uninstall.run()
+            try await self.validateInstalledToolchains(
+                [],
+                description: "uninstall did not uninstall all toolchains"
+            )
+        }
+    }
 }