diff --git a/TODO.md b/TODO.md
index 1d47a70..23decbc 100644
--- a/TODO.md
+++ b/TODO.md
@@ -3,7 +3,7 @@
 ## Tests
 
 - [ ] Commandline
-- [ ] File
+- [x] File
 - [ ] DynamoFile
 - [ ] PythonFile
 - [x] PythonNode
diff --git a/tests/support.py b/tests/support.py
index f8c6224..df7b054 100644
--- a/tests/support.py
+++ b/tests/support.py
@@ -1,4 +1,5 @@
 import pathlib
+import dyn2py
 
 INPUT_DIR = "tests/input_files"
 OUTPUT_DIR = "tests/output_files"
@@ -10,3 +11,15 @@ def cleanup_output_dir():
             f.unlink()
     else:
         output_dir.mkdir()
+
+
+def extract_single_node_dyn():
+    """Extract python from single_node.dyn
+        File will be here: f"{OUTPUT_DIR}/single_node_1c5d99792882409e97e132b3e9f814b0.py"
+    """
+    cleanup_output_dir()
+
+    # Extract py:
+    options = dyn2py.Options(python_folder=OUTPUT_DIR)
+    dyn = dyn2py.DynamoFile(f"{INPUT_DIR}/single_node.dyn")
+    dyn.extract_python(options)
diff --git a/tests/test_File.py b/tests/test_File.py
index 3d0f9d3..5750fce 100644
--- a/tests/test_File.py
+++ b/tests/test_File.py
@@ -8,10 +8,6 @@ from tests.support import *
 
 class TestFile(unittest.TestCase):
 
-    # Methods to test:
-    #  is_dynamo_file
-    #  is_python_file
-
     def test_init(self):
         paths = [
             f"{INPUT_DIR}/python_nodes.dyn",
@@ -65,8 +61,12 @@ class TestFile(unittest.TestCase):
             self.assertFalse(the_file.modified)
 
     def test_newer(self):
+        # Touch a file, so it will be always newer than the others:
+        touched_file = pathlib.Path(f"{OUTPUT_DIR}/touched_file.py")
+        touched_file.touch()
+        newer_file = dyn2py.File(touched_file)
+
         older_file = dyn2py.File(f"{INPUT_DIR}/python_nodes.dyn")
-        newer_file = dyn2py.File(f"{INPUT_DIR}/no_python.dyn")
         nonexisting_file = dyn2py.File(f"{INPUT_DIR}/new_file.dyn")
 
         self.assertTrue(newer_file.is_newer(older_file))
@@ -88,3 +88,21 @@ class TestFile(unittest.TestCase):
 
         with self.assertRaises(TypeError):
             nonexisting_file.write(options)
+
+    def test_is_file(self):
+
+        extract_single_node_dyn()
+
+        paths = [
+            (f"{INPUT_DIR}/python_nodes.dyn", "dyn"),
+            (f"{OUTPUT_DIR}/single_node_1c5d99792882409e97e132b3e9f814b0.py", "py"),
+            (f"README.md", ""),
+        ]
+
+        for path, f in paths:
+            file = dyn2py.File(path)
+            
+            self.assertEqual(file.is_dynamo_file(), f=="dyn")
+            self.assertEqual(file.is_python_file(), f=="py")
+
+            
diff --git a/tests/test_PythonNode.py b/tests/test_PythonNode.py
index 13bf889..e910547 100644
--- a/tests/test_PythonNode.py
+++ b/tests/test_PythonNode.py
@@ -32,12 +32,7 @@ class TestPythonNode(unittest.TestCase):
 
     def test_init_from_py(self):
 
-        cleanup_output_dir()
-
-        # Extract py:
-        options = dyn2py.Options(python_folder=OUTPUT_DIR)
-        dyn = dyn2py.DynamoFile(f"{INPUT_DIR}/single_node.dyn")
-        dyn.extract_python(options)
+        extract_single_node_dyn()
 
         # Open the extracted file and replace a string:
         with open(f"{OUTPUT_DIR}/single_node_1c5d99792882409e97e132b3e9f814b0.py") as orig_py, \