Add 'ShellError', which may be thrown from completed shell commands.

SwiftShell/Command.swift

@@ -42,6 +42,7 @@ extension ShellContextType {
 	}
 }
 
+
 extension ShellContextType {
 
 	private func outputFromRun (task: NSTask) -> String {
@@ -82,6 +83,22 @@ extension ShellContextType {
 	}
 }
 
+
+/** Error type for completed shell commands. */
+public enum ShellError: ErrorType, Equatable {
+
+	/** Exit code was not zero. */
+	case ReturnedErrorCode (errorcode: Int32)
+}
+
+public func == (e1: ShellError, e2: ShellError) -> Bool {
+	switch (e1, e2) {
+	case (.ReturnedErrorCode(let c1), .ReturnedErrorCode(let c2)):
+		return c1 == c2
+	}
+}
+
+/** Output from the 'runAsync' methods. */
 public struct AsyncShellTask {
 	public let stdout: NSFileHandle
 	public let stderror: NSFileHandle
@@ -104,10 +121,13 @@ public struct AsyncShellTask {
 	/** 
    Wait for this shell task to finish.
 
-   - throws: a TaskError if the return code is anything but 0.
+   - throws: a ShellError if the return code is anything but 0.
 	*/
 	public func finish() throws {
 		task.waitUntilExit()
+		if task.terminationStatus != 0 {
+			throw ShellError.ReturnedErrorCode(errorcode: task.terminationStatus)
+		}
 	}
 }
 

SwiftShellTests/Command_Tests.swift

@@ -44,8 +44,10 @@ class RunAsync_Tests: XCTestCase {
 		XCTAssertEqual( asynctask.stdout.read(), "" )
 	}
 
+	func testThrowsErrorOnExitcodeNotZero () {
+		let asynctask = main.runAsync(bash: "echo errormessage > /dev/stderr; exit 1" )
 
-		XCTAssertEqual( asynctask.stderror.read(), "one two\n" )
-		XCTAssertEqual( asynctask.stdout.read(), "" )
+		AssertThrows(ShellError.ReturnedErrorCode(errorcode: 1)) { try asynctask.finish() }
+		XCTAssertEqual( asynctask.stderror.read(), "errormessage\n" )
 	}
 }