feat(signatures): read a directory of markdown signatures

One file per signature under a directory the caller names, the stem being
the name shown to the user. A name containing a path separator is refused:
it arrives from the config file, and it reaches a path that is read into a
message about to be sent.

Part of item 152.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KEcn3u19xPqv6ggD15PG4c

1 files changed, 104 insertions, 0 deletions

diff --git a/tests/test_signatures.cpp b/tests/test_signatures.cpp
new file mode 100644
index 0000000..2a75067
--- /dev/null
+++ b/tests/test_signatures.cpp
@@ -0,0 +1,104 @@
+/*
+ * qtmaildir - a Qt6 mail client for notmuch-indexed Maildirs
+ * Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <QtTest>
+#include <QTemporaryDir>
+
+#include "signatures.h"
+
+class TestSignatures : public QObject
+{
+    Q_OBJECT
+
+private slots:
+    void namesAreTheFileStemsSorted();
+    void namesIgnoreFilesThatAreNotMarkdown();
+    void aMissingDirectoryHasNoNames();
+    void textIsTheFileContent();
+    void textOfAnUnknownNameIsEmpty();
+
+private:
+    /// Writes \p files as name -> content into a fresh temporary directory.
+    static void write(const QTemporaryDir &dir,
+                      const QList<QPair<QString, QString>> &files);
+};
+
+void TestSignatures::write(const QTemporaryDir &dir,
+                           const QList<QPair<QString, QString>> &files)
+{
+    for (const auto &entry : files) {
+        QFile file(dir.path() + QStringLiteral("/") + entry.first);
+        QVERIFY(file.open(QIODevice::WriteOnly | QIODevice::Text));
+        file.write(entry.second.toUtf8());
+        file.close();
+    }
+}
+
+void TestSignatures::namesAreTheFileStemsSorted()
+{
+    QTemporaryDir dir;
+    QVERIFY(dir.isValid());
+    write(dir, { { QStringLiteral("work.md"), QStringLiteral("Work") },
+                 { QStringLiteral("brief.md"), QStringLiteral("Brief") } });
+
+    QCOMPARE(Signatures::names(dir.path()),
+             QStringList({ QStringLiteral("brief"), QStringLiteral("work") }));
+}
+
+void TestSignatures::namesIgnoreFilesThatAreNotMarkdown()
+{
+    QTemporaryDir dir;
+    QVERIFY(dir.isValid());
+    write(dir, { { QStringLiteral("work.md"), QStringLiteral("Work") },
+                 { QStringLiteral("notes.txt"), QStringLiteral("Not one") },
+                 { QStringLiteral("README"), QStringLiteral("Nor this") } });
+
+    QCOMPARE(Signatures::names(dir.path()),
+             QStringList({ QStringLiteral("work") }));
+}
+
+void TestSignatures::aMissingDirectoryHasNoNames()
+{
+    QTemporaryDir dir;
+    QVERIFY(dir.isValid());
+    const QString missing = dir.path() + QStringLiteral("/nothing-here");
+
+    QVERIFY(Signatures::names(missing).isEmpty());
+}
+
+void TestSignatures::textIsTheFileContent()
+{
+    QTemporaryDir dir;
+    QVERIFY(dir.isValid());
+    write(dir, { { QStringLiteral("work.md"),
+                   QStringLiteral("Jane Doe\n**qtmaildir**\n") } });
+
+    QCOMPARE(Signatures::text(dir.path(), QStringLiteral("work")),
+             QStringLiteral("Jane Doe\n**qtmaildir**\n"));
+}
+
+void TestSignatures::textOfAnUnknownNameIsEmpty()
+{
+    QTemporaryDir dir;
+    QVERIFY(dir.isValid());
+
+    QVERIFY(Signatures::text(dir.path(), QStringLiteral("absent")).isEmpty());
+}
+
+QTEST_MAIN(TestSignatures)
+#include "test_signatures.moc"