add breaking toJSON test

test/toJSON-test.js

@@ -0,0 +1,28 @@
+'use strict';
+
+var fs = require('fs');
+var path = require('path');
+var assert = require('assert');
+var elliptic = require('../lib/elliptic');
+var curves = elliptic.curves;
+var compare = assert.deepStrictEqual || assert.deepEqual;
+
+function exportPoint (p) {
+  return JSON.parse(JSON.stringify(p.toJSON()));
+}
+
+describe('toJSON <-> pointFromJSON symmetry', function() {
+  it('toJSON matches pointFromJSON', function () {
+    for (var key in curves) {
+      if (key === 'PresetCurve') continue;
+
+      var curve = curves[key];
+      if (!curve.g.toJSON) continue;
+
+      var exported = exportPoint(curve.g);
+      var reimported = curve.curve.pointFromJSON(exported);
+      var reexported = exportPoint(reimported);
+      compare(exported, reexported, 'toJSON is the inverse of pointFromJSON');
+    }
+  });
+});