split tests into multiple files, and fixed tests to work with refactor

test/test_helpers.py

@@ -0,0 +1,21 @@
+import tempfile
+
+class MockSubprocess():
+  def __init__(self):
+      self.last_call = None
+
+  def call(self, args):
+      self.last_call = args
+
+  def last_call_args(self):
+      return self.last_call
+
+def write_tempfile(text):
+    tempdir = tempfile.mkdtemp()
+    path = tempdir + "/test-file.txt"
+    with open(path, "w") as f:
+      f.write(text)
+      f.close()
+    return path
+
+