qml: refactor invoice amount checks, msat precision for lightning.

add qeconfig unit tests for conversion methods.

tests/test_qml_qeconfig.py

@@ -0,0 +1,66 @@
+from electrum import SimpleConfig
+from electrum.gui.qml.qeconfig import QEConfig
+from tests.qt_util import QETestCase, qt_test
+
+
+class TestConfig(QETestCase):
+    @classmethod
+    def setUpClass(cls):
+        QEConfig(SimpleConfig())
+
+    def setUp(self):
+        super().setUp()
+        self.q: QEConfig = QEConfig.instance
+        # raise Exception()  # NOTE: exceptions in setUp() will block the test
+
+    @qt_test
+    def test_satstounits(self):
+        self.q.config.BTC_AMOUNTS_DECIMAL_POINT = 5
+        self.assertEqual(self.q.satsToUnits(100_000), 1.0)
+        self.assertEqual(self.q.satsToUnits(1), 0.00001)
+        self.assertEqual(self.q.satsToUnits(0.001), 0.00000001)
+
+    @qt_test
+    def test_unitstosats(self):
+        qa = self.q.unitsToSats('')
+        self.assertTrue(qa.isEmpty)
+        qa = self.q.unitsToSats('0')
+        self.assertTrue(qa.isEmpty)
+        qa = self.q.unitsToSats('0.000')
+        self.assertTrue(qa.isEmpty)
+
+        self.q.config.BTC_AMOUNTS_DECIMAL_POINT = 5
+
+        qa = self.q.unitsToSats('1')
+        self.assertFalse(qa.isEmpty)
+        self.assertEqual(qa.satsInt, 100_000)
+        self.assertEqual(qa.msatsInt, 100_000_000)
+
+        qa = self.q.unitsToSats('1.001')
+        self.assertFalse(qa.isEmpty)
+        self.assertEqual(qa.satsInt, 100_100)
+        self.assertEqual(qa.msatsInt, 100_100_000)
+
+        qa = self.q.unitsToSats('1.000001')
+        self.assertFalse(qa.isEmpty)
+        self.assertEqual(qa.satsInt, 100_000)
+        self.assertEqual(qa.msatsInt, 100_000_100)
+
+        self.q.config.BTC_AMOUNTS_DECIMAL_POINT = 0
+
+        qa = self.q.unitsToSats('1.001')
+        self.assertFalse(qa.isEmpty)
+        self.assertEqual(qa.satsInt, 1)
+        self.assertEqual(qa.msatsInt, 1001)
+
+        qa = self.q.unitsToSats('1.0001')  # outside msat precision
+        self.assertFalse(qa.isEmpty)
+        self.assertEqual(qa.satsInt, 1)
+        self.assertEqual(qa.msatsInt, 1000)
+
+        self.q.config.BTC_AMOUNTS_DECIMAL_POINT = 8
+
+        qa = self.q.unitsToSats('0.00000001001')
+        self.assertFalse(qa.isEmpty)
+        self.assertEqual(qa.satsInt, 1)
+        self.assertEqual(qa.msatsInt, 1001)