Add test to look for wei precision.

test/unit/components/bn-as-decimal-input-test.js

@@ -48,4 +48,40 @@ describe('BnInput', function () {
       checkValidity () { return true } },
     })
   })
+  
+  it('can tolerate wei precision', function (done) {
+    const renderer = ReactTestUtils.createRenderer()
+
+    let valueStr = '1000000000000000000'
+
+    const value = new BN(valueStr, 10)
+
+    const inputStr = '1000000000.000000001'
+
+    let targetStr = '1000000000000000001'
+
+    const target = new BN(targetStr, 10)
+
+    const precision = 9 // ether precision
+    const scale = 9
+
+    const props = {
+      value,
+      scale,
+      precision,
+      onChange: (newBn) => {
+        assert.equal(newBn.toString(), target.toString(), 'should tolerate increase')
+        done()
+      },
+    }
+
+    const inputComponent = h(BnInput, props)
+    const component = additions.renderIntoDocument(inputComponent)
+    renderer.render(inputComponent)
+    const input = additions.find(component, 'input.hex-input')[0]
+    ReactTestUtils.Simulate.change(input, { preventDefault () {}, target: {
+      value: inputStr,
+      checkValidity () { return true } },
+    })
+  })
 })