UB27-007__commit_email_formatter_diff_multiple_charsets: New testcase

Note that I verified that this testcase reproduces the issue
reported at #19
when using the legacy-python2 branch:

    | $ echo d408c32bba64a79fc60dbda8fa047524f353e7cd \
    |        28fbd651f8161bcba746f5dbcecf5ec757241c1d \
    |        refs/heads/master | \
    |        ./hooks/post-receive
    | [...]
    | UnicodeDecodeError: 'utf8' codec can't decode byte 0xf1 in
    |   position 425: invalid continuation byte

This testcase allows us to confirm that this issue was resolved
during the transition to Python 3.x.

Change-Id: Ia94dc584577e3b4d145fad7b7f89429a1b031849

testsuite/tests/UB27-007__commit_email_formatter_diff_multiple_charsets/bare_repo_config

@@ -0,0 +1,4 @@
+[core]
+	repositoryformatversion = 0
+	filemode = true
+	bare = true

testsuite/tests/UB27-007__commit_email_formatter_diff_multiple_charsets/commit-email-formatter.py

@@ -0,0 +1,5 @@
+#! /usr/bin/env python
+import sys
+import json
+
+json.dump({}, sys.stdout)

testsuite/tests/UB27-007__commit_email_formatter_diff_multiple_charsets/cvs_check.py

@@ -0,0 +1,2 @@
+#! /usr/bin/env python
+"""A dummy cvs_check program that does nothing."""

testsuite/tests/UB27-007__commit_email_formatter_diff_multiple_charsets/hooks_config

@@ -0,0 +1,4 @@
+[hooks]
+        from-domain = adacore.com
+        mailinglist = git-hooks-ci@example.com
+        filer-email = filer@example.com

testsuite/tests/UB27-007__commit_email_formatter_diff_multiple_charsets/run_test.py

@@ -0,0 +1,120 @@
+# coding=utf-8
+import os
+
+
+def test_push_commit_on_master(testcase):
+    """Try pushing one single-file commit on master.
+
+    The purpose of this testcase is to verify that the git-hooks
+    are able to pass the diff, which consists of 3 files all using
+    a different charset (ASCII, ISO-8859-15, and UTF-8), down to
+    the commit-email-formatter hook, without crashing.
+    """
+    # First, update the git-hooks configuration to install our
+    # the script we want to use as our commit-email-formatter.
+
+    p = testcase.run(["git", "fetch", "origin", "refs/meta/config"])
+    testcase.assertEqual(p.status, 0, p.image)
+
+    p = testcase.run(["git", "checkout", "FETCH_HEAD"])
+    testcase.assertEqual(p.status, 0, p.image)
+
+    p = testcase.run(
+        [
+            "git",
+            "config",
+            "--file",
+            "project.config",
+            "hooks.commit-email-formatter",
+            os.path.join(testcase.work_dir, "commit-email-formatter.py"),
+        ]
+    )
+    testcase.assertEqual(p.status, 0, p.image)
+
+    p = testcase.run(
+        [
+            "git",
+            "commit",
+            "-m",
+            "Add hooks.commit-email-formatter",
+            "project.config",
+        ]
+    )
+    testcase.assertEqual(p.status, 0, p.image)
+
+    p = testcase.run(["git", "push", "origin", "HEAD:refs/meta/config"])
+    testcase.assertEqual(p.status, 0, p.image)
+    # Check the last line that git printed, and verify that we have
+    # another piece of evidence that the change was succesfully pushed.
+    assert "HEAD -> refs/meta/config" in p.out.splitlines()[-1], p.image
+
+    # Return our current HEAD to branch "master". Not critical for
+    # our testing, but it helps the testcase be closer to the more
+    # typical scenarios.
+    p = testcase.run(["git", "checkout", "master"])
+    testcase.assertEqual(p.status, 0, p.image)
+
+    # Push master to the `origin' remote.
+    #
+    # The "diff" covers 3 files which are using different file
+    # encodings. The way we handle this in the commit email
+    # where each diff is shown, is by guessing the original
+    # encoding for each diff, decode that to unicode internally,
+    # and then sending the email using a consistent encoding
+    # across the entire email (utf-8).
+
+    p = testcase.run("git push origin master".split())
+    expected_out = """\
+remote: DEBUG: Content-Type: text/plain; charset="utf-8"
+remote: MIME-Version: 1.0
+remote: Content-Transfer-Encoding: base64
+remote: From: Test Suite <testsuite@adacore.com>
+remote: To: git-hooks-ci@example.com
+remote: Bcc: filer@example.com
+remote: Subject: [repo] Update all files
+remote: X-Act-Checkin: repo
+remote: X-Git-Author: Joel Brobecker <brobecker@adacore.com>
+remote: X-Git-Refname: refs/heads/master
+remote: X-Git-Oldrev: d408c32bba64a79fc60dbda8fa047524f353e7cd
+remote: X-Git-Newrev: 28fbd651f8161bcba746f5dbcecf5ec757241c1d
+remote:
+remote: commit 28fbd651f8161bcba746f5dbcecf5ec757241c1d
+remote: Author: Joel Brobecker <brobecker@adacore.com>
+remote: Date:   Sun Nov 28 09:12:09 2021 +0400
+remote:
+remote:     Update all files
+remote:
+remote: Diff:
+remote: ---
+remote:  ascii.txt       | 1 +
+remote:  iso-8859-15.txt | 1 +
+remote:  utf-8.txt       | 1 +
+remote:  3 files changed, 3 insertions(+)
+remote:
+remote: diff --git a/ascii.txt b/ascii.txt
+remote: index d94f50b..19fe92b 100644
+remote: --- a/ascii.txt
+remote: +++ b/ascii.txt
+remote: @@ -1 +1,2 @@
+remote:  This is a file with ASCII text only.
+remote: +Pretty restricted charset.
+remote: diff --git a/iso-8859-15.txt b/iso-8859-15.txt
+remote: index c629aad..555625f 100644
+remote: --- a/iso-8859-15.txt
+remote: +++ b/iso-8859-15.txt
+remote: @@ -1 +1,2 @@
+remote:  Español: ¿ Cómo te llamas, niño?
+remote: +Français: Un œuf corse (ou devrions nous dire «corsé»?)
+remote: diff --git a/utf-8.txt b/utf-8.txt
+remote: index ea83122..e29a0f4 100644
+remote: --- a/utf-8.txt
+remote: +++ b/utf-8.txt
+remote: @@ -1 +1,2 @@
+remote:  日本: 次のファイルから読み込み
+remote: +ประเทศไทย: ขอขอบคุณ
+To ../bare/repo.git
+   d408c32..28fbd65  master -> master
+"""
+
+    testcase.assertEqual(p.status, 0, p.image)
+    testcase.assertRunOutputEqual(p, expected_out)