LibJS: Add tests for Math constants

Author: https://github.com/linusg
Commit: https://github.com/SerenityOS/serenity/commit/402fd5a3a39
Pull-request: https://github.com/SerenityOS/serenity/pull/1529
Reviewed-by: https://github.com/awesomekling

Libraries/LibJS/Tests/Math-constants.js

@@ -0,0 +1,28 @@
+function assert(x) { if (!x) throw 1; }
+
+// FIXME: The parser seems to have issues with decimals,
+// so we multiply everything and compare with whole numbers.
+// I.e. 1233 < X * 1000 < 1235 instead of 1.233 < X < 1.235
+
+try {
+    // approx. 2.718
+    assert(2717 < Math.E * 1000 < 2719);
+    // approx. 0.693MATH
+    assert(692 < Math.LN2 * 1000 < 694);
+    // approx. 2.303
+    assert(2302 < Math.LN10 * 1000 < 2304);
+    // approx. 1.443
+    assert(1442 < Math.LOG2E * 1000 < 1444);
+    // approx. 0.434
+    assert(433 < Math.LOG10E * 1000 < 435);
+    // approx. 3.1415
+    assert(31414 < Math.PI * 10000 < 31416);
+    // approx. 0.707
+    assert(706 < Math.SQRT1_2 * 1000 < 708);
+    // approx. 1.414
+    assert(1413 < Math.SQRT2 * 1000 < 1415);
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}