Use list of tuples for multiple parameter BIP21 encoding tests

Dicts don't have guaranteed ordering.

Also now tests both with dicts and list of tuples for single parameter
tests.

All the actual code still use dicts, parameter order in BIP21 URI's in
real life should not matter.

jmbitcoin/test/test_bip21.py

@@ -68,37 +68,47 @@ def test_bip21_encode():
         }) ==
         'bitcoin:175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W?label=Luke-Jr'
     )
+    # Both dictionary and list of tuples should work
     assert(
-        btc.encode_bip21_uri('175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W', {
-            'amount': 20.3,
-            'label': 'Luke-Jr'
-        }) ==
+        btc.encode_bip21_uri('175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W', [
+            ('label', 'Luke-Jr')
+        ]) ==
+        'bitcoin:175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W?label=Luke-Jr'
+    )
+    # Use list of tuples version for multiple parameter tests, as dicts don't
+    # have guaranteed ordering.
+    assert(
+        btc.encode_bip21_uri('175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W', [
+            ('amount', 20.3),
+            ('label', 'Luke-Jr')
+        ]) ==
         'bitcoin:175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W?amount=20.3&label=Luke-Jr'
     )
     assert(
-        btc.encode_bip21_uri('175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W', {
-            'amount': 50,
-            'label': 'Luke-Jr',
-            'message': 'Donation for project xyz'
-        }) ==
+        btc.encode_bip21_uri('175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W', [
+            ('amount', 50),
+            ('label', 'Luke-Jr'),
+            ('message', 'Donation for project xyz')
+        ]) ==
         'bitcoin:175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W?amount=50&label=Luke-Jr&message=Donation%20for%20project%20xyz'
     )
     assert(
-        btc.encode_bip21_uri('175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W', {
-            'req-somethingyoudontunderstand': 50,
-            'req-somethingelseyoudontget': 999
-        }) ==
+        btc.encode_bip21_uri('175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W', [
+            ('req-somethingyoudontunderstand', 50),
+            ('req-somethingelseyoudontget', 999)
+        ]) ==
         'bitcoin:175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W?req-somethingyoudontunderstand=50&req-somethingelseyoudontget=999'
     )
     assert(
-        btc.encode_bip21_uri('175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W', {
-            'somethingyoudontunderstand': 50,
-            'somethingelseyoudontget': 999
-        }) ==
+        btc.encode_bip21_uri('175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W', [
+            ('somethingyoudontunderstand', 50),
+            ('somethingelseyoudontget', 999)
+        ]) ==
         'bitcoin:175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W?somethingyoudontunderstand=50&somethingelseyoudontget=999'
     )
     # Invalid amounts must raise ValueError
     with pytest.raises(ValueError):
+        # test dicts
         btc.encode_bip21_uri('175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W', {
             'amount': ''
         })
@@ -114,3 +124,20 @@ def test_bip21_encode():
         btc.encode_bip21_uri('175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W', {
             'amount': '100000000'
         })
+        # test list of tuples
+        btc.encode_bip21_uri('175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W', [
+            ('amount', '')
+        ])
+        btc.encode_bip21_uri('175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W', [
+            ('amount', 'XYZ')
+        ])
+        btc.encode_bip21_uri('175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W', [
+            ('amount', '100\'000')
+        ])
+        btc.encode_bip21_uri('175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W', [
+            ('amount', '100,000')
+        ])
+        btc.encode_bip21_uri('175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W', [
+            ('amount', '100000000')
+        ])
+