Add pyiron_workflow test (#156)

* Add pyiron_workflow test

* write functions to file

Author: jan-janssen

tests/test_pyiron_workflow.py

@@ -0,0 +1,43 @@
+import unittest
+import os
+from pyiron_workflow import Workflow, to_function_node
+from python_workflow_definition.pyiron_workflow import load_workflow_json, write_workflow_json
+
+function_str = """
+def get_prod_and_div(x, y):
+    return {"prod": x * y, "div": x / y}
+
+
+def get_sum(x, y):
+    return x + y
+
+
+def get_square(x):
+    return x ** 2
+"""
+
+
+class TestPyironWorkflow(unittest.TestCase):
+    def test_pyiron_workflow(self):
+        workflow_json_filename = "pyiron_workflow_arithmetic.json"
+        with open("workflow.py", "w") as f:
+            f.write(function_str)
+
+        from workflow import get_prod_and_div as _get_prod_and_div
+        from workflow import get_sum as _get_sum
+        from workflow import get_square as _get_square
+
+        get_prod_and_div = to_function_node("get_prod_and_div", _get_prod_and_div, "get_prod_and_div")
+        get_sum = to_function_node("get_sum", _get_sum, "get_sum")
+        get_square = to_function_node("get_square", _get_square, "get_square")
+        wf = Workflow("my_workflow")
+        wf.x = 1
+        wf.y = 2
+        wf.prod_and_div = get_prod_and_div(x=wf.x, y=wf.y)
+        wf.tmp_sum = get_sum(x=wf.prod_and_div["prod"], y=wf.prod_and_div["div"])
+        wf.square_result = get_square(x=wf.tmp_sum)
+        write_workflow_json(graph_as_dict=wf.graph_as_dict, file_name=workflow_json_filename)
+        wf = load_workflow_json(file_name=workflow_json_filename)
+        wf.run()
+
+        self.assertTrue(os.path.exists(workflow_json_filename))