execution test of actor keypaths

Author: kavon

test/Concurrency/Runtime/actor_keypaths.swift

@@ -0,0 +1,77 @@
+// RUN: %target-run-simple-swift(-Xfrontend -enable-experimental-concurrency %import-libdispatch)
+
+// REQUIRES: executable_test
+// REQUIRES: concurrency
+// REQUIRES: libdispatch
+
+actor Page {
+    let initialNumWords : Int
+
+    @actorIndependent(unsafe)
+    var numWords : Int
+
+    init(_ words : Int) {
+        numWords = words
+        initialNumWords = words
+    }
+}
+
+actor Book {
+    let pages : [Page]
+
+    init(_ numPages : Int) {
+        var stack : [Page] = []
+        for i in 0 ..< numPages {
+            stack.append(Page(i))
+        }
+        pages = stack
+    }
+
+    @actorIndependent
+    subscript(_ page : Int) -> Page {
+        return pages[page]
+    }
+}
+
+func bookHasChanged(_ b : Book,
+                    currentGetter : KeyPath<Page, Int>,
+                    initialGetter : (Page) -> Int) -> Bool {
+    let numPages = b[keyPath: \.pages.count]
+
+    for i in 0 ..< numPages {
+        let pageGetter = \Book.[i]
+        let currentWords = pageGetter.appending(path: currentGetter)
+
+        if (b[keyPath: currentWords] != initialGetter(b[keyPath: pageGetter])) {
+            return true
+        }
+    }
+
+    return false
+}
+
+func enumeratePageKeys(from : Int, to : Int) -> [KeyPath<Book, Page>] {
+    var keys : [KeyPath<Book, Page>] = []
+    for i in from ..< to {
+        keys.append(\Book.[i])
+    }
+    return keys
+}
+
+func erasePages(_ book : Book, badPages: [KeyPath<Book, Page>]) {
+    for page in badPages {
+        book[keyPath: page].numWords = 0
+    }
+}
+
+let book = Book(100)
+
+if bookHasChanged(book, currentGetter: \Page.numWords, initialGetter: \Page.initialNumWords) {
+    fatalError("book should not be changed")
+}
+
+erasePages(book, badPages: enumeratePageKeys(from: 0, to: 100))
+
+guard bookHasChanged(book, currentGetter: \Page.numWords, initialGetter: \Page.initialNumWords) else {
+    fatalError("book should be wiped!")
+}