Add CLI tests and improve coding style and i18n

The CLI module was lacking unit test coverage and showed some severe
coding style violations, which this patch addresses.

In addition, all uses of qCritical() with untranslatble raw char*
sequences were removed in favor of proper locale strings. These are
written to STDERR through QTextStreams and support output
redirection for testing purposes. With this change, error messages don't
depend on the global Qt logging settings and targets anymore and go
directly to the terminal or into a file if needed.

This patch also fixes a bug discovered during unit test development,
where the extract command would just dump the raw XML contents without
decrypting embedded Salsa20-protected values first, making the XML
export mostly useless, since passwords are scrambled.

Lastly, all CLI commands received a dedicated -h/--help option.

src/cli/Utils.cpp

@@ -25,9 +25,25 @@
 #endif
 
 #include <QProcess>
-#include <QTextStream>
 
-void Utils::setStdinEcho(bool enable = true)
+namespace Utils
+{
+/**
+ * STDOUT file handle for the CLI.
+ */
+FILE* STDOUT = stdout;
+
+/**
+ * STDERR file handle for the CLI.
+ */
+FILE* STDERR = stderr;
+
+/**
+ * STDIN file handle for the CLI.
+ */
+FILE* STDIN = stdin;
+
+void setStdinEcho(bool enable = true)
 {
 #ifdef Q_OS_WIN
     HANDLE hIn = GetStdHandle(STD_INPUT_HANDLE);
@@ -56,28 +72,55 @@ void Utils::setStdinEcho(bool enable = true)
 #endif
 }
 
-QString Utils::getPassword()
+QStringList nextPasswords = {};
+
+/**
+ * Set the next password returned by \link getPassword() instead of reading it from STDIN.
+ * Multiple calls to this method will fill a queue of passwords.
+ * This function is intended for testing purposes.
+ *
+ * @param password password to return next
+ */
+void setNextPassword(const QString& password)
 {
-    static QTextStream inputTextStream(stdin, QIODevice::ReadOnly);
-    static QTextStream outputTextStream(stdout, QIODevice::WriteOnly);
+    nextPasswords.append(password);
+}
+
+/**
+ * Read a user password from STDIN or return a password previously
+ * set by \link setNextPassword().
+ *
+ * @return the password
+ */
+QString getPassword()
+{
+    QTextStream out(STDOUT, QIODevice::WriteOnly);
+
+    // return preset password if one is set
+    if (!nextPasswords.isEmpty()) {
+        auto password = nextPasswords.takeFirst();
+        // simulate user entering newline
+        out << endl;
+        return password;
+    }
+
+    QTextStream in(STDIN, QIODevice::ReadOnly);
 
     setStdinEcho(false);
-    QString line = inputTextStream.readLine();
+    QString line = in.readLine();
     setStdinEcho(true);
-
-    // The new line was also not echoed, but we do want to echo it.
-    outputTextStream << "\n";
-    outputTextStream.flush();
+    out << endl;
 
     return line;
 }
 
-/*
+/**
  * A valid and running event loop is needed to use the global QClipboard,
  * so we need to use this from the CLI.
  */
-int Utils::clipText(const QString& text)
+int clipText(const QString& text)
 {
+    QTextStream err(Utils::STDERR);
 
     QString programName = "";
     QStringList arguments;
@@ -98,16 +141,18 @@ int Utils::clipText(const QString& text)
 #endif
 
     if (programName.isEmpty()) {
-        qCritical("No program defined for clipboard manipulation");
+        err << QObject::tr("No program defined for clipboard manipulation");
+        err.flush();
         return EXIT_FAILURE;
     }
 
-    QProcess* clipProcess = new QProcess(nullptr);
+    auto* clipProcess = new QProcess(nullptr);
     clipProcess->start(programName, arguments);
     clipProcess->waitForStarted();
 
     if (clipProcess->state() != QProcess::Running) {
-        qCritical("Unable to start program %s", qPrintable(programName));
+        err << QObject::tr("Unable to start program %1").arg(programName);
+        err.flush();
         return EXIT_FAILURE;
     }
 
@@ -120,3 +165,5 @@ int Utils::clipText(const QString& text)
 
     return clipProcess->exitCode();
 }
+
+}   // namespace Utils