Test with larger tables

[inverse-tax] / tax.test.js

diff --git a/tax.test.js b/tax.test.js
index 58995ef74db6ba1541d7eccc10bde6430870c4bd..29f436fa957586671113770afc7cd182ebe9074c 100644 (file)
--- a/tax.test.js
+++ b/tax.test.js
@@ -16,7 +16,7 @@ function rand(limit = 99) {
 
 function make_random_tax_table() {
   function make_random_table(min_threshold) {
-    if (rand(2)) return [];
+    if (rand(4) == 0) return [];
     const start = min_threshold === undefined ? rand() : min_threshold;
     const end = start + 1 + rand();
     return [[start, rand()]].concat(make_random_table(end));
@@ -61,4 +61,14 @@ test("invert", () => {
   assert.strictEqual(invert([[0, 100, .1], [100, Infinity, .2]])(170), 200);
   assert.strictEqual(invert([[0, 100, .1], [100, Infinity, .2]])(112), 127.5);
   assert.strictEqual(invert([[6, 90, 0.75], [90, Infinity, 0.12]])(27), 90);
+
+  for (var i = 0; i < 1000; i++) {
+    const t = make_random_tax_table();
+    const inverted_t = invert(t);
+    for (var j = 0; j < 20; j++) {
+      const net = rand(250);
+      const gross = inverted_t(net);
+      assert.ok(near(net, gross - tax(t, gross)));
+    }
+  }
 });