Add read from file test (#121)

Author: markaren

README.md

@@ -109,7 +109,7 @@ class PythonSlave(Fmi2Slave):
 
         # Note:
         # it is also possible to explicitly define getters and setters as lambdas in case the variable is not backed by a Python field.
-        # self.register_variable(Real("myReal", causality=Fmi2Causality.output, getter=lambda: self.realOut, setter=lambda v: self.realOut = v))
+        # self.register_variable(Real("myReal", causality=Fmi2Causality.output, getter=lambda: self.realOut, setter=lambda v: set_real_out(v))
 
     def do_step(self, current_time, step_size):
         return True

pythonfmu/tests/data/hello.txt

@@ -0,0 +1 @@
+Hello world!

pythonfmu/tests/slaves/pythonslave_read_file.py

@@ -0,0 +1,18 @@
+from pythonfmu.fmi2slave import Fmi2Slave, Fmi2Causality, Fmi2Variability, String
+
+
+class PythonSlaveReadFile(Fmi2Slave):
+
+    def __init__(self, **kwargs):
+        super().__init__(**kwargs)
+
+        with (open(f'{self.resources}/hello.txt', 'r')) as file:
+            data = file.read()
+
+        self.register_variable(
+            String("file_content", getter=lambda: data,
+                   causality=Fmi2Causality.output,
+                   variability=Fmi2Variability.constant))
+
+    def do_step(self, current_time, step_size):
+        return True

pythonfmu/tests/test_integration.py

@@ -174,6 +174,24 @@ def test_integration_get(tmp_path):
         assert model_value == value
 
 
+@pytest.mark.integration
+def test_integration_read_from_file(tmp_path):
+    script_file = Path(__file__).parent / "slaves/pythonslave_read_file.py"
+    project_file = Path(__file__).parent / "data/hello.txt"
+    fmu = FmuBuilder.build_FMU(script_file, project_files=[project_file], dest=tmp_path, needsExecutionTool="false")
+    assert fmu.exists()
+    model = pyfmi.load_fmu(str(fmu))
+
+    variables = model.get_model_variables()
+    var = variables["file_content"]
+    model_value = model.get_string([var.value_reference])[0]
+
+    with (open(project_file, 'r')) as file:
+        data = file.read()
+
+    assert model_value == data
+
+
 @pytest.mark.integration
 def test_integration_set(tmp_path):
     script_file = Path(__file__).parent / "slaves/pythonslave.py"