Test suites and code QA fixes

library/tests/setup.cfg

@@ -0,0 +1,8 @@
+[flake8]
+exclude =
+	__pycache__
+ignore =
+    D100 # Do not require docstrings
+	E501
+	F403
+	F405

library/tests/test_setup.py

@@ -0,0 +1,57 @@
+import sys
+import mock
+import pytest
+import bme680
+
+
+class MockSMBus:
+    """Mock a basic non-presence SMBus device to cause BME680 to fail.
+
+    Returns 0 in all cases, so that CHIP_ID will never match.
+
+    """
+
+    def __init__(self, bus):  # noqa D107
+        pass
+
+    def read_byte_data(self, addr, register):
+        """Return 0 for all read attempts."""
+        return 0
+
+
+class MockSMBusPresent:
+    """Mock enough of the BME680 for the library to initialise and test."""
+
+    def __init__(self, bus):
+        """Initialise with test data."""
+        self.regs = [0 for _ in range(256)]
+        self.regs[bme680.CHIP_ID_ADDR] = bme680.CHIP_ID
+
+    def read_byte_data(self, addr, register):
+        """Read a single byte from fake registers."""
+        return self.regs[register]
+
+    def write_byte_data(self, addr, register, value):
+        """Write a single byte to fake registers."""
+        self.regs[register] = value
+
+    def read_i2c_block_data(self, addr, register, length):
+        """Read up to length bytes from register."""
+        return self.regs[register:register + length]
+
+
+def test_setup_not_present():
+    """Mock the adbsence of a BME680 and test initialisation."""
+    sys.modules['smbus'] = mock.MagicMock()
+    sys.modules['smbus'].SMBus = MockSMBus
+
+    with pytest.raises(RuntimeError):
+        sensor = bme680.BME680()  # noqa F841
+
+
+def test_setup_mock_present():
+    """Mock the presence of a BME680 and test initialisation."""
+    sys.modules['smbus'] = mock.MagicMock()
+    sys.modules['smbus'].SMBus = MockSMBusPresent
+
+    sensor = bme680.BME680()  # noqa F841