Merge 1c251dc into 7af287c

src/quantuminspire/projectq/backend_qx.py

@@ -30,6 +30,7 @@
                           Measure, Ph, Rx, Ry, Rz, S, Sdag, Swap, T, Tdag, X,
                           Y, Z, Command)
 from projectq.types import Qubit
+from quantuminspire.exceptions import ApiError
 from quantuminspire.api import QuantumInspireAPI
 from quantuminspire.exceptions import ProjectQBackendError
 
@@ -47,7 +48,7 @@ def __init__(self, num_runs: int = 1024, verbose: int = 0, quantum_inspire_api:
         Args:
             num_runs: Number of runs to collect statistics (default is 1024).
             verbose: Verbosity level, defaults to 0, which produces no extra output.
-            quantum_inspire_api: Connection to QI platform, required parameter.
+            quantum_inspire_api: Connection to QI platform, optional parameter.
             backend_type: Backend to use for execution. When no backend_type is provided, the default backend will be
                           used.
         """
@@ -63,8 +64,12 @@ def __init__(self, num_runs: int = 1024, verbose: int = 0, quantum_inspire_api:
         self._measured_ids: List[int] = []
         self._allocated_qubits: Set[int] = set()
         self._max_qubit_id: int = -1
-        if not quantum_inspire_api:
-            raise RuntimeError("Api is required")
+        if quantum_inspire_api is None:
+            try:
+                quantum_inspire_api = QuantumInspireAPI()
+            except ApiError as ex:
+                raise ApiError('Make sure you have saved your token credentials on disk (see README.md) or '
+                               'provide a QuantumInspireAPI instance as parameter to QIBackend') from ex
         self.quantum_inspire_api: QuantumInspireAPI = quantum_inspire_api
         self.backend_type: Optional[Union[Dict[str, Any], int, str]] = backend_type
 

src/tests/quantuminspire/projectq/test_backend_qx.py

@@ -18,6 +18,9 @@
 import io
 import unittest
 import warnings
+import json
+import os
+import coreapi
 from collections import OrderedDict
 from unittest.mock import MagicMock, patch
 
@@ -27,7 +30,7 @@
                           Ph, Rx, Ry, Rz, S, Sdag, Swap, T, Tdag, Toffoli, X,
                           Y, Z)
 
-from quantuminspire.exceptions import ProjectQBackendError
+from quantuminspire.exceptions import ProjectQBackendError, ApiError
 from quantuminspire.projectq.backend_qx import QIBackend
 
 
@@ -51,9 +54,23 @@ def test_init_has_correct_values(self):
         self.assertEqual(backend.quantum_inspire_api, api)
         self.assertIsNone(backend.backend_type)
 
-    def test_init_raises_runtime_error(self):
-        api = None
-        self.assertRaises(RuntimeError, QIBackend, quantum_inspire_api=api)
+    def test_init_without_api_has_correct_values(self):
+        os.environ.get = MagicMock()
+        os.environ.get.return_value = 'token'
+        coreapi.Client.get = MagicMock()
+        backend = QIBackend()
+        self.assertIsInstance(backend.qasm, str)
+        self.assertNotEqual(backend.quantum_inspire_api, None)
+        self.assertIsNone(backend.backend_type)
+
+    def test_init_raises_no_account_api_error(self):
+        json.load = MagicMock()
+        json.load.return_value = {'faulty_key': 'faulty_token'}
+        os.environ.get = MagicMock()
+        os.environ.get.return_value = None
+        self.assertRaisesRegex(ApiError, 'Make sure you have saved your token credentials on disk \(see README\.md\) '
+                                         'or provide a QuantumInspireAPI instance as parameter to QIBackend',
+                               QIBackend)
 
     def test_cqasm_returns_correct_cqasm_data(self):
         api = MockApiClient()