🎉 Initial commit

tests/test_integration_pymodbus.py

@@ -0,0 +1,87 @@
+"""Integration test: pymodbus as an independent Modbus TCP master.
+
+Verifies the simulator against a third-party client implementation
+(rather than our own codec) — the strongest interop check for FAT use.
+
+Uses the pymodbus 3.15 async client API (device_id= keyword).
+"""
+
+from __future__ import annotations
+
+import asyncio
+
+import pytest
+
+pymodbus = pytest.importorskip("pymodbus")
+from pymodbus.client import AsyncModbusTcpClient  # noqa: E402
+
+
+async def _start(app, port=15021):
+    app.server.host, app.server.port = "127.0.0.1", port
+    await app.server.start()
+    await asyncio.sleep(0.05)
+
+
+class TestPymodbusInterop:
+    async def test_constants_via_pymodbus(self, app):
+        await _start(app)
+        client = AsyncModbusTcpClient("127.0.0.1", port=15021)
+        assert await client.connect()
+        try:
+            rr = await client.read_holding_registers(0x2000, count=9, device_id=1)
+            assert not rr.isError()
+            assert rr.registers == [0x0000, 0xFFFF, 0x1234, 0xAAAA, 0x5555,
+                                    0x7FFF, 0x8000, 0x3FFF, 0x4000]
+        finally:
+            client.close()
+            await app.server.stop()
+
+    async def test_write_read_process_image(self, app):
+        await _start(app)
+        client = AsyncModbusTcpClient("127.0.0.1", port=15021)
+        assert await client.connect()
+        try:
+            # write holding register 0 (-> output %QW0)
+            await client.write_register(0, 0x1234, device_id=1)
+            # read back via the input-register mirror at +0x0200
+            rr = await client.read_input_registers(0x0200, count=1, device_id=1)
+            assert rr.registers == [0x1234]
+            # coil write & read-back mirror at 0x0200
+            await client.write_coil(3, True, device_id=1)
+            rr = await client.read_coils(0x0200, count=8, device_id=1)
+            assert rr.bits[3] is True
+        finally:
+            client.close()
+            await app.server.stop()
+
+    async def test_illegal_address_exception(self, app):
+        await _start(app)
+        client = AsyncModbusTcpClient("127.0.0.1", port=15021)
+        assert await client.connect()
+        try:
+            rr = await client.read_holding_registers(0x0100, count=1, device_id=1)
+            assert rr.isError()
+            assert rr.exception_code == 0x02
+        finally:
+            client.close()
+            await app.server.stop()
+
+    async def test_read_write_multiple_registers(self, app):
+        await _start(app)
+        client = AsyncModbusTcpClient("127.0.0.1", port=15021)
+        assert await client.connect()
+        try:
+            # FC23: read the constant 0x1234 at 0x2002 while writing %QW0
+            rr = await client.readwrite_registers(
+                read_address=0x2002, read_count=1,
+                write_address=0x0000, values=[0xBEEF],
+                device_id=1,
+            )
+            assert not rr.isError()
+            assert rr.registers == [0x1234]
+            # the write part landed in the output image -> mirror at 0x0200
+            rr = await client.read_input_registers(0x0200, count=1, device_id=1)
+            assert rr.registers == [0xBEEF]
+        finally:
+            client.close()
+            await app.server.stop()