LibJS: Add tests for value to number conversion

Author: https://github.com/linusg
Commit: https://github.com/SerenityOS/serenity/commit/c698cc899d6
Pull-request: https://github.com/SerenityOS/serenity/pull/1528

Libraries/LibJS/Tests/to-number-basic.js

@@ -0,0 +1,33 @@
+function assert(x) { if (!x) throw 1; }
+
+// FIXME: Just "+x" doesn't parse currently,
+// so we use "x - 0", which is effectively the same.
+// "0 + x" would _not_ work in all cases.
+function n(x) { return x - 0; }
+
+try {
+    assert(n(false) === 0);
+    assert(n(true) === 1);
+    assert(n(null) === 0);
+    assert(n([]) === 0);
+    assert(n([[[[[]]]]]) === 0);
+    assert(n([[[[[42]]]]]) === 42);
+    assert(n("") === 0);
+    assert(n("42") === 42);
+    assert(n(42) === 42);
+    // FIXME: returns NaN
+    // assert(n("1.23") === 1.23)
+    // FIXME: chokes on ASSERT
+    // assert(n(1.23) === 1.23);
+
+    assert(isNaN(n(undefined)));
+    assert(isNaN(n({})));
+    assert(isNaN(n({a: 1})));
+    assert(isNaN(n([1, 2, 3])));
+    assert(isNaN(n([[[["foo"]]]])));
+    assert(isNaN(n("foo")));
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}