Properly swallow errors if deleting a remote fails (#505)

`deleteRemote()` intends to return successfully if
the to-be-deleted remote does not exist. In this case, git returns an
exit code of 2, and outputs a message to stderr. Depending on the locale
of the user's system, this error message might be localized.
`spawnPromise()` and `spawnStream()` try to set the locale to `en_US`,
but there are no guarantees that this locale is actually available on
the user's system.

Instead of doing fragile locale-dependent string parsing, simply use the
exit code we get from git in this case and act on that.

Fix the mocks in the tests to behave like the real-world git, and add a
test for the non-English case as well.

Co-authored-by: Søren Louv-Jansen <sorenlouv@gmail.com>

src/lib/git.test.ts

@@ -364,12 +364,24 @@ describe('deleteRemote', () => {
     repoName: 'kibana',
   } as ValidConfigOptions;
 
-  it('should swallow SpawnError error', async () => {
+  it('should swallow "no such remote" error', async () => {
     const err = new childProcess.SpawnError({
-      code: 128,
+      code: 2,
+      cmdArgs: [],
+      stdout: '',
+      stderr: "fatal: No such remote: 'my-remote'\n",
+    });
+
+    jest.spyOn(childProcess, 'spawnPromise').mockRejectedValueOnce(err);
+    await expect(await deleteRemote(options, remoteName)).toBe(undefined);
+  });
+
+  it('should swallow "no such remote" error, even if it is not in English', async () => {
+    const err = new childProcess.SpawnError({
+      code: 2,
       cmdArgs: [],
       stdout: '',
-      stderr: "fatal: No such remote: 'origin'\n",
+      stderr: "Fehler: Remote-Repository nicht gefunden: 'my-remote'\n",
     });
 
     jest.spyOn(childProcess, 'spawnPromise').mockRejectedValueOnce(err);

src/lib/git.ts

@@ -191,11 +191,10 @@ export async function deleteRemote(
   } catch (e) {
     const isSpawnError = e instanceof SpawnError;
 
-    if (
-      isSpawnError &&
-      e.context.code > 0 &&
-      e.context.stderr.includes('No such remote')
-    ) {
+    // Swallow the "remote does not exist" failure, indicated by a return
+    // code of 2. From `git help remote`: "When subcommands such as add, rename,
+    // and remove can’t find the remote in question, the exit status is 2."
+    if (isSpawnError && e.context.code == 2) {
       return;
     }