Don't clear the output dir when generating markdown (#92)

* Don't clear the output dir when generating markdown

* Don't use distutils.dir_utils

* Fix a typo

Author: Dexterp37

glean_parser/translate.py

@@ -9,6 +9,7 @@
 """
 
 from pathlib import Path
+import os
 import shutil
 import sys
 import tempfile
@@ -18,7 +19,15 @@
 from . import markdown
 
 
-OUTPUTTERS = {"kotlin": kotlin.output_kotlin, "markdown": markdown.output_markdown}
+# Each outputter in the table has the following keys:
+# - "output_func": the main function of the outputter, the one which
+#   does the actual translation.
+# - "clear_output_dir": a flag to clear the target directory before moving there
+#   the generated files.
+OUTPUTTERS = {
+    "kotlin": {"output_func": kotlin.output_kotlin, "clear_output_dir": True},
+    "markdown": {"output_func": markdown.output_markdown, "clear_output_dir": False},
+}
 
 
 def translate(input_filepaths, output_format, output_dir, options={}, parser_config={}):
@@ -49,13 +58,24 @@ def translate(input_filepaths, output_format, output_dir, options={}, parser_con
     # Write everything out to a temporary directory, and then move it to the
     # real directory, for transactional integrity.
     with tempfile.TemporaryDirectory() as tempdir:
-        OUTPUTTERS[output_format](all_objects.value, Path(tempdir), options)
+        tempdir_path = Path(tempdir)
+        OUTPUTTERS[output_format]["output_func"](
+            all_objects.value, tempdir_path, options
+        )
 
-        if output_dir.is_file():
-            output_dir.unlink()
-        elif output_dir.is_dir():
-            shutil.rmtree(output_dir)
+        if OUTPUTTERS[output_format]["clear_output_dir"]:
+            if output_dir.is_file():
+                output_dir.unlink()
+            elif output_dir.is_dir():
+                shutil.rmtree(output_dir)
 
-        shutil.copytree(tempdir, output_dir)
+            shutil.copytree(tempdir, output_dir)
+        else:
+            # We can't use shutil.copytree alone if the directory already exists.
+            # However, if it doesn't exist, make sure to create one otherwise
+            # shutil.copy will fail.
+            os.makedirs(output_dir, exist_ok=True)
+            for filename in tempdir_path.glob("*"):
+                shutil.copy(filename, output_dir)
 
     return 0

tests/test_translate.py

@@ -6,6 +6,7 @@
 from pathlib import Path
 
 import pytest
+import shutil
 
 from glean_parser import parser
 from glean_parser import translate
@@ -36,7 +37,7 @@ def test_translate_missing_directory(tmpdir):
     assert len(list(output.iterdir())) == 5
 
 
-def test_translate_remove_obsolete_files(tmpdir):
+def test_translate_remove_obsolete_kotlin_files(tmpdir):
     output = Path(tmpdir) / "foo"
 
     translate.translate(
@@ -53,6 +54,27 @@ def test_translate_remove_obsolete_files(tmpdir):
     assert len(list(output.iterdir())) == 1
 
 
+def test_translate_retains_existing_markdown_files(tmpdir):
+    output = Path(tmpdir) / "foo"
+
+    translate.translate(
+        ROOT / "data" / "core.yaml",
+        "markdown",
+        output,
+        parser_config={"allow_reserved": True},
+    )
+
+    # Move the file to a different location, translate always writes to
+    # metrics.md.
+    shutil.move(output / "metrics.md", output / "old.md")
+
+    assert len(list(output.iterdir())) == 1
+
+    translate.translate(ROOT / "data" / "smaller.yaml", "markdown", output)
+
+    assert len(list(output.iterdir())) == 2
+
+
 def test_translate_expires():
     contents = [
         {