tools/setup: replace generated args.gn unless handcrafted

tools/setup_test.py

@@ -0,0 +1,61 @@
+# Copyright 2018 the Deno authors. All rights reserved. MIT license.
+
+import os
+from setup import read_gn_args, write_gn_args
+from shutil import rmtree
+from tempfile import mktemp
+
+
+def read_gn_args_test():
+    # Args file doesn't exist.
+    (args, hand_edited) = read_gn_args("/baddir/hopefully/nonexistent/args.gn")
+    assert args is None
+    assert hand_edited == False
+
+    # Handwritten empty args file.
+    filename = mktemp()
+    with open(filename, "w"):
+        pass
+    (args, hand_edited) = read_gn_args(filename)
+    os.remove(filename)
+    assert args == []
+    assert hand_edited == True
+
+    # Handwritten non-empty args file.
+    expect_args = ['some_number=2', 'another_string="ran/dom#yes"']
+    filename = mktemp()
+    with open(filename, "w") as f:
+        f.write("\n".join(expect_args + ["", "# A comment to be ignored"]))
+    (args, hand_edited) = read_gn_args(filename)
+    os.remove(filename)
+    assert args == expect_args
+    assert hand_edited == True
+
+
+def write_gn_args_test():
+    # Build a nonexistent path; write_gn_args() should call mkdir as needed.
+    dir = mktemp()
+    filename = os.path.join(dir, "args.gn")
+    assert not os.path.exists(dir)
+    assert not os.path.exists(filename)
+    # Write some args.
+    args = ['lalala=42', 'foo_bar_baz="lorem ipsum dolor#amet"']
+    write_gn_args(filename, args)
+    # Directory and args file should now be created.
+    assert os.path.isdir(dir)
+    assert os.path.isfile(filename)
+    # Validate that the right contents were written.
+    (check_args, hand_edited) = read_gn_args(filename)
+    assert check_args == args
+    assert hand_edited == False
+    # Clean up.
+    rmtree(dir)
+
+
+def setup_test():
+    read_gn_args_test()
+    write_gn_args_test()
+
+
+if __name__ == '__main__':
+    setup_test()