diff --git a/src/backends/R/rexpression.cpp b/src/backends/R/rexpression.cpp
index 373f8ded..b72ab7da 100644
--- a/src/backends/R/rexpression.cpp
+++ b/src/backends/R/rexpression.cpp
@@ -1,150 +1,150 @@
 /*
     This program is free software; you can redistribute it and/or
     modify it under the terms of the GNU General Public License
     as published by the Free Software Foundation; either version 2
     of the License, or (at your option) any later version.
 
     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.
 
     ---
     Copyright (C) 2009 Alexander Rieder <alexanderrieder@gmail.com>
  */
 
 #include "rexpression.h"
 
 #include "textresult.h"
 #include "imageresult.h"
 #include "helpresult.h"
 #include "epsresult.h"
 #include "rsession.h"
 
 
 #include <QDebug>
 #include <KLocalizedString>
 #include <QMimeType>
 #include <QMimeDatabase>
 #include <QFile>
 #include <QStringList>
 #include <QTextDocument>
 
 RExpression::RExpression( Cantor::Session* session, bool internal ) : Cantor::Expression(session, internal),
 m_isHelpRequest(false)
 {
 
 }
 
 void RExpression::evaluate()
 {
     if(command().startsWith(QLatin1Char('?')))
         m_isHelpRequest=true;
     else
         m_isHelpRequest=false;
 
     session()->enqueueExpression(this);
 }
 
 void RExpression::interrupt()
 {
     qDebug()<<"interrupting command";
     setStatus(Cantor::Expression::Interrupted);
 }
 
 void RExpression::finished(int returnCode, const QString& text)
 {
     if (status() == Expression::Interrupted)
         return;
 
     if(returnCode==RExpression::SuccessCode)
     {
         qDebug() << "text: " << text;
-        setResult(new Cantor::TextResult(text));
+        if (!text.trimmed().isEmpty())
+            addResult(new Cantor::TextResult(text));
         setStatus(Cantor::Expression::Done);
     }else if (returnCode==RExpression::ErrorCode)
     {
         qDebug() << "text: " << text;
-        //setResult(new Cantor::TextResult(text));
         setErrorMessage(text);
         setStatus(Cantor::Expression::Error);
     }
 }
 
 void RExpression::addInformation(const QString& information)
 {
     static_cast<RSession*>(session())->sendInputToServer(information);
 }
 
 void RExpression::showFilesAsResult(const QStringList& files)
 {
     qDebug()<<"showing files: "<<files;
     foreach(const QString& file, files)
     {
         QMimeType type;
         QMimeDatabase db;
 
         type=db.mimeTypeForUrl(QUrl(file));
         qDebug()<<"MimeType: "<<type.name();
         if(type.inherits(QLatin1String("application/postscript")))
         {
             qDebug()<<"its PostScript";
             setResult(new Cantor::EpsResult(QUrl::fromLocalFile(file)));
         }
         else if(type.inherits(QLatin1String("text/plain"))
             || type.inherits(QLatin1String("application/x-extension-html")))
         {
             //Htmls are also plain texts, combining this in one
             const bool isHtml = type.inherits(QLatin1String("text/html"))
                 || type.inherits(QLatin1String("application/x-extension-html"));
             if(isHtml)
                 qDebug()<<"its a HTML document";
             else
                 qDebug()<<"its plain text";
 
             QFile f(file);
             if (!f.open(QIODevice::ReadOnly | QIODevice::Text))
             {
                 setResult(new Cantor::TextResult(i18n("Error opening file %1", file)));
                 setErrorMessage(i18n("Error opening file %1", file));
                 setStatus(Cantor::Expression::Error);
             }
             QString content=QTextStream(&f).readAll();
             if (!isHtml)
             {
                 //Escape whitespace
                 content.replace( QLatin1Char(' '), QLatin1String("&nbsp;"));
                 //replace appearing backspaces, as they mess the whole output up
                 content.remove(QRegExp(QLatin1String(".\b")));
             }
 
             qDebug()<<"content: "<<content;
             if(m_isHelpRequest)
                 setResult(new Cantor::HelpResult(content));
             else
                 setResult(new Cantor::TextResult(content));
             setStatus(Cantor::Expression::Done);
         }else if (type.name().contains(QLatin1String("image")))
         {
             setResult(new Cantor::ImageResult(QUrl::fromLocalFile(file)));
             setStatus(Cantor::Expression::Done);
         }
         else
         {
             // File has unsupported mime type, but we suspect, that it is text, so will open the file in Cantor script editor
             // Even if it don't text, the script editor can deals with it.
             setStatus(Cantor::Expression::Done);
             const QString& editor = QStandardPaths::findExecutable(QLatin1String("cantor_scripteditor"));
             int code = QProcess::execute(editor, QStringList(file));
             if (code == -2)
                 qDebug() << "failed to open the file " << file << " with the script editor '" << editor << "'";
             else if (code == -1)
                 qDebug() << "Cantor script editor crashed";
         }
     }
 }
diff --git a/src/backends/R/testr.cpp b/src/backends/R/testr.cpp
index 6c034c67..94eaef58 100644
--- a/src/backends/R/testr.cpp
+++ b/src/backends/R/testr.cpp
@@ -1,88 +1,214 @@
 /*
     This program is free software; you can redistribute it and/or
     modify it under the terms of the GNU General Public License
     as published by the Free Software Foundation; either version 2
     of the License, or (at your option) any later version.
 
     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.
 
     ---
     Copyright (C) 2019 Sirgienko Nikita <warquark@gmail.com>
  */
 
 #include "testr.h"
 
 #include "session.h"
 #include "backend.h"
 #include "expression.h"
 #include "result.h"
 #include "completionobject.h"
 #include "defaultvariablemodel.h"
 
 #include <QDebug>
 
 
 QString TestR::backendName()
 {
     return QLatin1String("R");
 }
 
+void TestR::testSimpleCommand()
+{
+    Cantor::Expression* e=evalExp( QLatin1String("2+2") );
+
+    QVERIFY( e!=nullptr );
+    QVERIFY( e->result()!=nullptr );
+
+    QCOMPARE( cleanOutput( e->result()->data().toString() ), QLatin1String("[1] 4") );
+}
+
+void TestR::testMultilineCommand()
+{
+    Cantor::Expression* e = evalExp(QLatin1String("print(2+2)\nprint(7*5)"));
+
+    QVERIFY(e != nullptr);
+    QVERIFY(e->result() != nullptr);
+    QCOMPARE(cleanOutput( e->result()->data().toString() ), QLatin1String("[1] 4\n[1] 35"));
+}
+
+void TestR::testCodeWithComments()
+{
+    Cantor::Expression* e=evalExp( QLatin1String("2+2 #comment") );
+
+    QVERIFY( e!=nullptr );
+    QVERIFY( e->result()!=nullptr );
+
+    QCOMPARE( cleanOutput( e->result()->data().toString() ), QLatin1String("[1] 4") );
+}
+
+void TestR::testCommandQueue()
+{
+    Cantor::Expression* e1=session()->evaluateExpression(QLatin1String("0+1"));
+    Cantor::Expression* e2=session()->evaluateExpression(QLatin1String("1+1"));
+    Cantor::Expression* e3=evalExp(QLatin1String("1+2"));
+
+    qDebug() << e1 << e1->command() << e1->status();
+    qDebug() << e2 << e2->command() << e2->status();
+    qDebug() << e3 << e3->command() << e3->status();
+
+    QVERIFY(e1!=nullptr);
+    QVERIFY(e2!=nullptr);
+    QVERIFY(e3!=nullptr);
+
+    QVERIFY(e1->result());
+    QVERIFY(e2->result());
+    QVERIFY(e3->result());
+
+    QCOMPARE(cleanOutput(e1->result()->data().toString()), QLatin1String("[1] 1"));
+    QCOMPARE(cleanOutput(e2->result()->data().toString()), QLatin1String("[1] 2"));
+    QCOMPARE(cleanOutput(e3->result()->data().toString()), QLatin1String("[1] 3"));
+}
+
 void TestR::testVariablesCreatingFromCode()
 {
     QAbstractItemModel* model = session()->variableModel();
     QVERIFY(model != nullptr);
 
     Cantor::Expression* e=evalExp(QLatin1String("a1 = 15; b1 = 'S'; d1 = c(1,2,3)"));
+
     QVERIFY(e!=nullptr);
+    QVERIFY(e->result() != nullptr);
 
-    while(session()->status() != Cantor::Session::Done)
+    while (session()->status() != Cantor::Session::Done)
         waitForSignal(session(), SIGNAL(statusChanged(Cantor::Session::Status)));
 
-    QCOMPARE(3, model->rowCount());
+    QCOMPARE(model->rowCount(), 3);
 
     QCOMPARE(model->index(0,0).data().toString(), QLatin1String("a1"));
     QCOMPARE(model->index(0,1).data().toString(), QLatin1String("15"));
 
     QCOMPARE(model->index(1,0).data().toString(), QLatin1String("b1"));
     QCOMPARE(model->index(1,1).data().toString(), QLatin1String("S"));
 
     QCOMPARE(model->index(2,0).data().toString(), QLatin1String("d1"));
     QCOMPARE(model->index(2,1).data().toString(), QLatin1String("1, 2, 3"));
 
     evalExp(QLatin1String("rm(a1,b1,d1)"));
 }
 
 void TestR::testVariableCleanupAfterRestart()
 {
-    Cantor::DefaultVariableModel* model = session()->variableModel();
+    QAbstractItemModel* model = session()->variableModel();
     QVERIFY(model != nullptr);
 
     while(session()->status() != Cantor::Session::Done)
         waitForSignal(session(), SIGNAL(statusChanged(Cantor::Session::Status)));
 
-    QCOMPARE(static_cast<QAbstractItemModel*>(model)->rowCount(), 0);
+    QCOMPARE(model->rowCount(), 0);
 
     Cantor::Expression* e=evalExp(QLatin1String("h1 = 15; h2 = 'S';"));
     QVERIFY(e!=nullptr);
 
-    while(session()->status() != Cantor::Session::Done)
+    while (session()->status() != Cantor::Session::Done)
         waitForSignal(session(), SIGNAL(statusChanged(Cantor::Session::Status)));
 
-    QCOMPARE(static_cast<QAbstractItemModel*>(model)->rowCount(), 2);
+    QCOMPARE(model->rowCount(), 2);
 
     session()->logout();
     session()->login();
 
-    QCOMPARE(static_cast<QAbstractItemModel*>(model)->rowCount(), 0);
+    QCOMPARE(model->rowCount(), 0);
+}
+
+void TestR::testVariableDefinition()
+{
+    Cantor::Expression* e = evalExp(QLatin1String("testvar <- \"value\"; testvar"));
+
+    QVERIFY(e != nullptr);
+    QCOMPARE(e->status(), Cantor::Expression::Done);
+    QVERIFY(e->result() != nullptr);
+    QCOMPARE(cleanOutput(e->result()->data().toString()), QLatin1String("[1] \"value\""));
+
+    evalExp(QLatin1String("rm(testvar)"));
+}
+
+void TestR::testMatrixDefinition()
+{
+    Cantor::Expression* e = evalExp(QLatin1String("matrix(1:9, nrow = 3, ncol = 3)"));
+
+    QVERIFY(e != nullptr);
+    QCOMPARE(e->status(), Cantor::Expression::Done);
+    QVERIFY(e->result() != nullptr);
+    QCOMPARE(e->result()->data().toString(), QLatin1String(
+         "     [,1] [,2] [,3]\n"
+         "[1,]    1    4    7\n"
+         "[2,]    2    5    8\n"
+         "[3,]    3    6    9"
+    ));
+}
+
+void TestR::testCommentExpression()
+{
+    Cantor::Expression* e = evalExp(QLatin1String("#only comment"));
+
+    QVERIFY(e != nullptr);
+    QCOMPARE(e->status(), Cantor::Expression::Status::Done);
+    QCOMPARE(e->results().size(), 0);
+}
+
+void TestR::testMultilineCommandWithComment()
+{
+    Cantor::Expression* e = evalExp(QLatin1String(
+        "print(2+2) \n"
+        "#comment in middle \n"
+        "print(7*5)"));
+
+    QVERIFY(e != nullptr);
+    QVERIFY(e->result()->data().toString() == QLatin1String("[1] 4\n[1] 35"));
+}
+
+void TestR::testInvalidSyntax()
+{
+    Cantor::Expression* e=evalExp( QLatin1String("2+2*+?!<") );
+
+    QVERIFY( e!=nullptr );
+    QCOMPARE( e->status(), Cantor::Expression::Error );
+}
+
+void TestR::testCompletion()
+{
+    Cantor::CompletionObject* help = session()->completionFor(QLatin1String("pi"), 2);
+    waitForSignal(help, SIGNAL(fetchingDone()));
+
+    // Checks all completions for this request
+    // This correct for R 3.4.4
+    const QStringList& completions = help->completions();
+    qDebug() << completions;
+    QCOMPARE(completions.size(), 5);
+    QVERIFY(completions.contains(QLatin1String("pi")));
+    QVERIFY(completions.contains(QLatin1String("pico")));
+    QVERIFY(completions.contains(QLatin1String("pictex")));
+    QVERIFY(completions.contains(QLatin1String("pie")));
+    QVERIFY(completions.contains(QLatin1String("pipe")));
 }
 
 QTEST_MAIN( TestR )
 
diff --git a/src/backends/R/testr.h b/src/backends/R/testr.h
index 9c09e175..60492cf3 100644
--- a/src/backends/R/testr.h
+++ b/src/backends/R/testr.h
@@ -1,39 +1,57 @@
 /*
     This program is free software; you can redistribute it and/or
     modify it under the terms of the GNU General Public License
     as published by the Free Software Foundation; either version 2
     of the License, or (at your option) any later version.
 
     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.
 
     ---
     Copyright (C) 2019 Sirgienko Nikita <warquark@gmail.com>
  */
 
 #ifndef _TESTR_H
 #define _TESTR_H
 
 #include "backendtest.h"
 
 class TestR : public BackendTest
 {
   Q_OBJECT
-
 private Q_SLOTS:
+    void testSimpleCommand();
+    void testMultilineCommand();
+    void testCommandQueue();
+
+    void testVariableDefinition();
+    void testMatrixDefinition();
+
+    void testCodeWithComments();
+    void testCommentExpression();
+    void testMultilineCommandWithComment();
+
+    void testInvalidSyntax();
+
+    void testCompletion();
+    //void testHelpRequest();
+    //void testSyntaxHelp();
+
+    //void testPlot();
+
     //tests variable model
     void testVariablesCreatingFromCode();
     void testVariableCleanupAfterRestart();
 
 private:
     QString backendName() override;
 };
 
 #endif /* _TESTR_H */