LibJS: Implement basic for..in and for..of loops

Libraries/LibJS/Tests/Array.prototype-generic-functions.js

@@ -73,67 +73,47 @@ try {
     const o = { length: 5, 0: "foo", 1: "bar", 3: "baz" };
 
     {
-        const visited = [];
-        Array.prototype.every.call(o, function (value) {
-            visited.push(value);
-            return true;
-        });
-        assert(visited.length === 3);
-        assert(visited[0] === "foo");
-        assert(visited[1] === "bar");
-        assert(visited[2] === "baz");
+        assertVisitsAll(visit => {
+            Array.prototype.every.call(o, function (value) {
+                visit(value);
+                return true;
+            });
+        }, ["foo", "bar", "baz"]);
     }
 
     ["find", "findIndex"].forEach(name => {
-        const visited = [];
-        Array.prototype[name].call(o, function (value) {
-            visited.push(value);
-            return false;
-        });
-        assert(visited.length === 5);
-        assert(visited[0] === "foo");
-        assert(visited[1] === "bar");
-        assert(visited[2] === undefined);
-        assert(visited[3] === "baz");
-        assert(visited[4] === undefined);
+        assertVisitsAll(visit => {
+            Array.prototype[name].call(o, function (value) {
+                visit(value);
+                return false;
+            });
+        }, ["foo", "bar", undefined, "baz", undefined]);
     });
 
     ["filter", "forEach", "map", "some"].forEach(name => {
-        const visited = [];
-        Array.prototype[name].call(o, function (value) {
-            visited.push(value);
-            return false;
-        });
-        assert(visited.length === 3);
-        assert(visited[0] === "foo");
-        assert(visited[1] === "bar");
-        assert(visited[2] === "baz");
+        assertVisitsAll(visit => {
+            Array.prototype[name].call(o, function (value) {
+                visit(value);
+                return false;
+            });
+        }, ["foo", "bar", "baz"]);
     });
-
     {
-        const visited = [];
-        Array.prototype.reduce.call(o, function (_, value) {
-            visited.push(value);
-            return false;
-        }, "initial");
-
-        assert(visited.length === 3);
-        assert(visited[0] === "foo");
-        assert(visited[1] === "bar");
-        assert(visited[2] === "baz");
+        assertVisitsAll(visit => {
+            Array.prototype.reduce.call(o, function (_, value) {
+                visit(value);
+                return false;
+            }, "initial");
+        }, ["foo", "bar", "baz"]);
     }
 
     {
-        const visited = [];
-        Array.prototype.reduceRight.call(o, function (_, value) {
-            visited.push(value);
-            return false;
-        }, "initial");
-
-        assert(visited.length === 3);
-        assert(visited[2] === "foo");
-        assert(visited[1] === "bar");
-        assert(visited[0] === "baz");
+        assertVisitsAll(visit => {
+            Array.prototype.reduceRight.call(o, function (_, value) {
+                visit(value);
+                return false;
+            }, "initial");
+        }, ["baz", "bar", "foo"]);
     }
 
     console.log("PASS");

Libraries/LibJS/Tests/for-in-basic.js

@@ -0,0 +1,41 @@
+load("test-common.js");
+
+try {
+    assertVisitsAll(visit => {
+        for (const property in "") {
+            visit(property);
+        }
+    }, []);
+
+    assertVisitsAll(visit => {
+        for (const property in 123) {
+            visit(property);
+        }
+    }, []);
+
+    assertVisitsAll(visit => {
+        for (const property in {}) {
+            visit(property);
+        }
+    }, []);
+
+    assertVisitsAll(visit => {
+        for (const property in "hello") {
+            visit(property);
+        }
+    }, ["0", "1", "2", "3", "4"]);
+
+    assertVisitsAll(visit => {
+        for (const property in {a: 1, b: 2, c: 2}) {
+            visit(property);
+        }
+    }, ["a", "b", "c"]);
+
+    var property;
+    for (property in "abc");
+    assert(property === "2");
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}

Libraries/LibJS/Tests/for-of-basic.js

@@ -0,0 +1,43 @@
+load("test-common.js");
+
+try {
+    assertThrowsError(() => {
+        for (const _ of 123) {}
+    }, {
+        error: TypeError,
+        message: "for..of right-hand side must be iterable"
+    });
+
+    assertThrowsError(() => {
+        for (const _ of {foo: 1, bar: 2}) {}
+    }, {
+        error: TypeError,
+        message: "for..of right-hand side must be iterable"
+    });
+
+    assertVisitsAll(visit => {
+        for (const num of [1, 2, 3]) {
+            visit(num);
+        }
+    }, [1, 2, 3]);
+
+    assertVisitsAll(visit => {
+        for (const char of "hello") {
+            visit(char);
+        }
+    }, ["h", "e", "l", "l", "o"]);
+
+    assertVisitsAll(visit => {
+        for (const char of new String("hello")) {
+            visit(char);
+        }
+    }, ["h", "e", "l", "l", "o"]);
+
+    var char;
+    for (char of "abc");
+    assert(char === "c");
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}

Libraries/LibJS/Tests/test-common.js

@@ -50,6 +50,13 @@ function assertThrowsError(testFunction, options) {
     }
 }
 
+const assertVisitsAll = (testFunction, expectedOutput) => {
+    const visited = [];
+    testFunction(value => visited.push(value));
+    assert(visited.length === expectedOutput.length);
+    expectedOutput.forEach((value, i) => assert(visited[i] === value));
+};
+
 /**
  * Check whether the difference between two numbers is less than 0.000001.
  * @param {Number} a First number