tests: verify ECPair loops until within interval

test/ecpair.js

@@ -169,6 +169,16 @@ describe('ECPair', function () {
 
       assert.strictEqual(keyPair.toWIF(), exWIF)
     })
+
+    it('loops until d is within interval [1, n - 1]', sinon.test(function () {
+      var rng = this.mock()
+      rng.exactly(3)
+      rng.onCall(0).returns(new BigInteger('0').toBuffer(32)) // < 1
+      rng.onCall(1).returns(curve.n.toBuffer(32)) // > n-1
+      rng.onCall(2).returns(new BigInteger('42').toBuffer(32)) // valid
+
+      ECPair.makeRandom({ rng: rng })
+    }))
   })
 
   describe('getAddress', function () {