Merge pull request #33 from poponealex/30-uninstalled-git-raises-a-wi…

…nerror-2-which-is-not-caught-by-subprocesscalledprocesserror

deal with missing git

src/renamings.py

@@ -12,6 +12,7 @@ class Renamer:
     def __init__(self, context: Context, testing: bool = False):
         self.logger = context.logger
         self.print_ = context.print_
+        self.rename_one_file = self._rename_one_file_with_git  # set the default renaming strategy
         if testing:
             self.logger.create_new_log_file()
 
@@ -68,26 +69,51 @@ def get_arcs_for_undoing(
     def rename_and_log_all_files(self, arcs: List[Arc]):
         self.arcs_to_rollback: List[Arc] = []
         for (source, target) in arcs:
-            try:
-                subprocess.run(
-                    [
-                        "git",  # git fails when launched from a non-versioned directory.
-                        "-C",  # This option runs git as if it was started...
-                        source.parent,  #  ... in the source's parent directory.
-                        "mv",
-                        source.name,
-                        target.name,
-                    ],
-                    check=True,
-                    stderr=subprocess.DEVNULL,
-                )
-            except subprocess.CalledProcessError:
-                source.rename(target)
+            git_flag = self.rename_one_file(source, target)
+            self.logger.info(f"{'git:' if git_flag else ''}SOURCE:{source}\tTARGET:{target}")
             self.arcs_to_rollback.insert(0, Arc(target, source))
-            self.logger.info(f"SOURCE:{source}\tTARGET:{target}")
         self.print_arcs(arcs)
         self.print_.newline()
 
+    def _rename_one_file_with_git(self, source: Path, target: Path) -> bool:
+        """Try to use git to operate a renaming (default strategy for `rename_one_file()`).
+
+        Args:
+            source (Path): the path to the file to rename
+            target (Path): the new path to the file
+
+        Returns:
+            bool: `True` if the renaming was done using git, `False` otherwise. In the latter case,
+                the renaming is done without git, as well as all the subsequent ones.
+        """
+        try:
+            subprocess.run(
+                [
+                    "git",
+                    "-C",  # Run git as if it was started...
+                    source.parent,  #  ... from the source's parent directory.
+                    "mv",
+                    source.name,
+                    target.name,
+                ],
+                check=True,
+                stderr=subprocess.DEVNULL,
+            )
+            return True
+        except FileNotFoundError:
+            self.rename_one_file = self._rename_one_file
+            self.logger.warning(f"Git is not installed. Falling back to a non-git strategy.")
+        except subprocess.CalledProcessError:
+            pass
+        except Exception as e:
+            self.logger.warning(f"Error while git-renaming '{source}' to '{target}': {e}.")
+        return self._rename_one_file(source, target)
+
+    def _rename_one_file(self, source: Path, target: Path) -> bool:
+        """Fallback strategy as soon as a git-renaming has found that git was not installed."""
+        source.rename(target)
+        return False
+
     def print_arcs(self, arcs: List[Arc]):
         previous_parent = Path()
         for (source, target) in arcs:

test/test_renamings.py

@@ -1,5 +1,6 @@
 from pathlib import Path
 
+import os
 import pytest
 
 __import__("sys").path[0:0] = "."
@@ -259,5 +260,56 @@ def test_undo_with_empty_log_file():
     arcs_for_undoing = renamer.get_arcs_for_undoing(logger.get_contents()) # doesn't raise an exception
     assert arcs_for_undoing == []
 
+
+def test_rename_when_git_is_not_installed():
+    """All renamings succeed."""
+    renamer = Renamer(context, testing=True)
+    base = Path("test") / "happy_path"
+    rm_tree(base)
+    base.mkdir()
+    arcs = [
+        Arc(base / "source_0", base / "target_0"),
+        Arc(base / "source_1", base / "target_1"),
+        Arc(base / "source_2", base / "target_2"),
+    ]
+    for arc in arcs:
+        arc.source.touch()
+    path_backup = os.environ["PATH"]
+    os.environ["PATH"] = ""  # make git unavailable
+    renamer.perform_renamings(arcs)
+    os.environ["PATH"] = path_backup
+    assert set(base.iterdir()) == set(arc.target for arc in arcs)
+    print(logger.get_contents())
+    assert logger.get_contents() == "\n".join([
+        "INFO:root:3 items to rename.",
+        "WARNING:root:Git is not installed. Falling back to a non-git strategy.",
+        "INFO:root:SOURCE:test/happy_path/source_0\tTARGET:test/happy_path/target_0",
+        "INFO:root:SOURCE:test/happy_path/source_1\tTARGET:test/happy_path/target_1",
+        "INFO:root:SOURCE:test/happy_path/source_2\tTARGET:test/happy_path/target_2",
+        "INFO:root:3 items renamed.",
+    ])
+    rm_tree(base)
+
+
+def test_rename_files_under_version_control():
+    """Swap to files under version control."""
+    renamer = Renamer(context, testing=True)
+    base = Path("test")
+    arcs = [
+        Arc(base / "test_renamings_data_1.md", base / "test_renamings_data_aux.md"),
+        Arc(base / "test_renamings_data_2.md", base / "test_renamings_data_1.md"),
+        Arc(base / "test_renamings_data_aux.md", base / "test_renamings_data_2.md"),
+    ]
+    renamer.perform_renamings(arcs)
+    print(logger.get_contents())
+    assert logger.get_contents() == "\n".join([
+        "INFO:root:3 items to rename.",
+        "INFO:root:git:SOURCE:test/test_renamings_data_1.md\tTARGET:test/test_renamings_data_aux.md",
+        "INFO:root:git:SOURCE:test/test_renamings_data_2.md\tTARGET:test/test_renamings_data_1.md",
+        "INFO:root:git:SOURCE:test/test_renamings_data_aux.md\tTARGET:test/test_renamings_data_2.md",
+        "INFO:root:3 items renamed.",
+    ])
+
+
 if __name__ == "__main__":  # pragma: no cover
     pytest.main(["-qq", __import__("sys").argv[0]])

test/test_renamings_data_1.md

@@ -0,0 +1,3 @@
+# About this file
+
+The purpose of `test_renamings_data_1.md` and `test_renamings_data_2.md` is to test the renaming of files under version control. Launching `test_renamings.py` simply swaps their names. Since they have the same content, this operation has no impact on the commit history.

test/test_renamings_data_2.md

@@ -0,0 +1,3 @@
+# About this file
+
+The purpose of `test_renamings_data_1.md` and `test_renamings_data_2.md` is to test the renaming of files under version control. Launching `test_renamings.py` simply swaps their names. Since they have the same content, this operation has no impact on the commit history.