Add test for Test module.

Fixtures/SwiftTesting/SingleTarget/Sources/Foo/Foo.swift

@@ -0,0 +1,3 @@
+func ten() -> Int {
+    return 10
+}

Fixtures/SwiftTesting/SingleTarget/Tests/Foo/Test.swift

@@ -0,0 +1,17 @@
+@testable import Foo
+import XCTest
+
+class SimpleGetTests: XCTestCase {
+
+    func testGetRequestStatusCode() {
+        XCTAssertEqual(ten(), 10)
+    }
+}
+
+extension SimpleGetTests {
+    static var allTests : [(String, SimpleGetTests -> () throws -> Void)]  {
+        return [
+            ("testGetRequestStatusCode", testGetRequestStatusCode),
+        ]
+    }
+}

Fixtures/SwiftTesting/SingleTarget/Tests/LinuxMain.swift

@@ -0,0 +1,7 @@
+import XCTest
+
+@testable import FooTestSuite
+
+XCTMain([
+    testCase(SimpleGetTests.allTests),
+])

Tests/Functional/TestMiscellaneous.swift

@@ -349,4 +349,18 @@ class MiscellaneousTestCase: XCTestCase {
             XCTAssertFileExists(prefix, ".build/debug/libBar.a")
         }
     }
+
+    func testModuleWithTests() {
+        fixture(name: "SwiftTesting/SingleTarget") { prefix in
+            XCTAssertBuilds(prefix)
+            XCTAssertFileExists(prefix, ".build", "debug", "Foo.swiftmodule")
+            XCTAssertTests(prefix)
+            #if os(OSX)
+                XCTAssertDirectoryExists(prefix, ".build", "debug", "Package.xctest")
+            #else
+                XCTAssertFileExists(prefix, ".build", "debug", "test-Package")
+            #endif
+
+        }
+    }
 }

Tests/Functional/TestValidLayouts.swift

@@ -181,6 +181,7 @@ extension MiscellaneousTestCase {
             ("testInternalDependencyEdges", testInternalDependencyEdges),
             ("testExternalDependencyEdges1", testExternalDependencyEdges1),
             ("testExternalDependencyEdges2", testExternalDependencyEdges2),
+            ("testModuleWithTests", testModuleWithTests),
         ]
     }
 }

Tests/Functional/Utilities.swift

@@ -133,6 +133,43 @@ func executeSwiftBuild(chdir: String, configuration: Configuration = .Debug, pri
     }
 }
 
+//FIXME: rafactor to use a common dir for swift-build and swift-test
+func swiftTestPath() -> String {
+    #if os(OSX)
+        for bundle in NSBundle.allBundles() where bundle.bundlePath.hasSuffix(".xctest") {
+            return Path.join(bundle.bundlePath.parentDirectory, "swift-test")
+        }
+        fatalError()
+    #else
+        return Path.join(try! Process.arguments.first!.abspath().parentDirectory, "swift-test")
+    #endif
+}
+
+//TODO: refactor swift-build and swift-test tools runing
+func executeSwiftTest(dir: String, printIfError: Bool = false) throws -> String {
+    let toolPath = swiftTestPath()
+    let env = [String:String]()
+    let args = [toolPath]
+
+    var out = ""
+    do {
+        // FIXME: this probably should be refactored to --chdir arg in swift-test
+        let cwd = try getcwd()
+        defer { _ = try? POSIX.chdir(cwd) }
+        try POSIX.chdir(dir)
+
+        try popen(args, redirectStandardError: true, environment: env) {
+            out += $0
+        }
+        return out
+    } catch {
+        if printIfError {
+            print(out)
+        }
+        throw error
+    }
+}
+
 func mktmpdir(file: StaticString = #file, line: UInt = #line, @noescape body: (String) throws -> Void) {
     do {
         try POSIX.mkdtemp("spm-tests") { dir in
@@ -171,6 +208,16 @@ func XCTAssertBuildFails(paths: String..., file: StaticString = #file, line: UIn
     }
 }
 
+func XCTAssertTests(paths: String..., file: StaticString = #file, line: UInt = #line) {
+    let prefix = Path.join(paths)
+    do {
+        print("    Testing")
+        try executeSwiftTest(prefix, printIfError: true)
+    } catch {
+        XCTFail("swift-test failed:\n\n\(error)\n", file: file, line: line)
+    }
+}
+
 func XCTAssertFileExists(paths: String..., file: StaticString = #file, line: UInt = #line) {
     let path = Path.join(paths)
     if !path.isFile {