diff --git a/.gitignore b/.gitignore
index 3f4df27..09a1857 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,7 +12,5 @@ harbour-patience-deck
 /dist/screenshots/*.png
 /installroot/
 /tools/convert
-/tools/exerciser/games/
-/tools/exerciser/engine-exerciser
 .qmake.stash
 /libs/
diff --git a/tools/exerciser/.gitignore b/tools/exerciser/.gitignore
new file mode 100644
index 0000000..f4b1ba9
--- /dev/null
+++ b/tools/exerciser/.gitignore
@@ -0,0 +1,2 @@
+/games/
+/engine-exerciser
diff --git a/tools/itertest/.gitignore b/tools/itertest/.gitignore
new file mode 100644
index 0000000..501a8e0
--- /dev/null
+++ b/tools/itertest/.gitignore
@@ -0,0 +1 @@
+/itertest
diff --git a/tools/itertest/itertest.cpp b/tools/itertest/itertest.cpp
new file mode 100644
index 0000000..0a5a847
--- /dev/null
+++ b/tools/itertest/itertest.cpp
@@ -0,0 +1,314 @@
+/*
+ * Tests for Patience Deck itertools
+ * Copyright (C) 2023 Tomi Leppänen
+ *
+ * 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, version 3 of the License.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <iostream>
+#include <random>
+#include <string>
+#include <unordered_set>
+#include <vector>
+#include "itertools.h"
+
+#define ASSERT_TRUE(test) do { \
+    if (!(test)) { \
+        cout << "assertion (" << #test << ") is true failed" << endl; \
+        return false; \
+    } \
+} while (0)
+#define ASSERT_FALSE(test) do { \
+    if (test) { \
+        cout << "assertion (" << #test << ") is false failed" << endl; \
+        return false; \
+        return false; \
+    } \
+} while (0)
+#define ASSERT_SAME(a, b) do { \
+    if ((a) != (b)) { \
+        cout << "assertion (" << #a << " == " << #b << ") failed" << endl; \
+        return false; \
+    } \
+} while (0)
+#define SUCCESS() do { return true; } while (0)
+
+namespace {
+    using std::advance;
+    using std::cout;
+    using std::endl;
+    using std::function;
+    using std::get;
+    using std::mt19937;
+    using std::string;
+    using std::tuple;
+    using std::unitbuf;
+    using std::unordered_set;
+    using std::vector;
+
+    const vector<int> data { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
+} // namespace
+
+bool test_range_simple()
+{
+    Range range(0, 10);
+    auto it1 = range.begin();
+    auto it2 = data.begin();
+    while (it1 != range.end() || it2 != data.end()) {
+        ASSERT_SAME(*it1, *it2);
+        ++it1, ++it2;
+    }
+    ASSERT_FALSE(it1 != range.end());
+    ASSERT_TRUE(it2 == data.end());
+    SUCCESS();
+}
+
+bool test_range_consistent_begin()
+{
+    Range range(0, 100);
+    auto first = range.begin();
+    auto second = range.begin();
+    ASSERT_FALSE(first != second);
+    ASSERT_TRUE(++first != second);
+    ASSERT_FALSE(first != ++second);
+    SUCCESS();
+}
+
+bool test_range_consistent_end()
+{
+    Range range(10, 12);
+    ASSERT_SAME(range.end(), range.end());
+    auto it = range.begin();
+    advance(it, 4);
+    ASSERT_SAME(it, range.end());
+    SUCCESS();
+}
+
+bool test_range_empty()
+{
+    Range range(1, 1);
+    ASSERT_SAME(range.begin(), range.end());
+    SUCCESS();
+}
+
+bool test_indexed_simple()
+{
+    vector<int> indices { 8, 9, 2, 5, 4, 3, 6, 7, 1, 0 };
+    vector<int> values(data); 
+    IndexedIterator<vector<int>::iterator> iterator(values.begin(), values.end(), indices);
+    auto it1 = iterator.begin();
+    auto it2 = indices.begin();
+    while (it1 != iterator.end() || it2 != indices.end()) {
+        ASSERT_SAME(*it1, *it2);
+        ++it1, ++it2;
+    }
+    ASSERT_FALSE(it1 != iterator.end());
+    ASSERT_TRUE(it2 == indices.end());
+    SUCCESS();
+}
+
+bool test_indexed_consistent_begin()
+{
+    IndexedIterator<vector<int>::const_iterator> iterator(data.begin(), data.end(), data);
+    auto first = iterator.begin();
+    auto second = iterator.begin();
+    ASSERT_FALSE(first != second);
+    ASSERT_TRUE(++first != second);
+    ASSERT_FALSE(first != ++second);
+    SUCCESS();
+}
+
+bool test_indexed_consistent_end()
+{
+    IndexedIterator<vector<int>::const_iterator> iterator(data.begin(), data.end(), data);
+    ASSERT_SAME(iterator.end(), iterator.end());
+    auto it = iterator.begin();
+    advance(it, 10);
+    ASSERT_SAME(it, iterator.end());
+    SUCCESS();
+}
+
+bool test_indexed_empty()
+{
+    IndexedIterator<vector<int>::const_iterator> iterator(data.begin(), data.begin(), std::vector<int>());
+    ASSERT_SAME(iterator.begin(), iterator.end());
+    SUCCESS();
+}
+
+bool test_shuffled_simple(int value, const vector<int> &expected)
+{
+    vector<int> values(data);
+    mt19937 generator(value);
+    IndexedIterator<vector<int>::iterator> iterator = shuffled(values, generator);
+    auto it1 = iterator.begin();
+    auto it2 = expected.begin();
+    while (it1 != iterator.end() || it2 != expected.end()) {
+        ASSERT_SAME(*it1, *it2);
+        ++it1, ++it2;
+    }
+    ASSERT_FALSE(it1 != iterator.end());
+    ASSERT_TRUE(it2 == expected.end());
+    SUCCESS();
+}
+
+bool test_shuffled_simple_0()
+{
+    const vector<int> expected { 0, 2, 1, 5, 9, 8, 4, 7, 6, 3 };
+    return test_shuffled_simple(0, expected);
+}
+
+bool test_shuffled_simple_42()
+{
+    const vector<int> expected { 1, 6, 7, 0, 5, 9, 8, 2, 3, 4 };
+    return test_shuffled_simple(42, expected);
+}
+
+bool test_grouped_simple()
+{
+    vector<int> groups { 3, 2, 4, 1 };
+    vector<int> values(data);
+    GroupedIterator<vector<int>::iterator> iterator(values.begin(), values.end(), groups);
+    vector<vector<int>> expected {
+        { 0, 1, 2 },
+        { 3, 4 },
+        { 5, 6, 7, 8 },
+        { 9 },
+    };
+    auto itA1 = iterator.begin();
+    auto itA2 = expected.begin();
+    while (itA1 != iterator.end() || itA2 != expected.end()) {
+        auto itB1 = (*itA1).begin();
+        auto itB2 = itA2->begin();
+        while (itB1 != (*itA1).end() || itB2 != itA2->end()) {
+            ASSERT_SAME(*itB1, *itB2);
+            ++itB1, ++itB2;
+        }
+        ASSERT_FALSE(itB1 != (*itA1).end());
+        ASSERT_TRUE(itB2 == itA2->end());
+        ++itA1, ++itA2;
+    }
+    ASSERT_FALSE(itA1 != iterator.end());
+    ASSERT_TRUE(itA2 == expected.end());
+    SUCCESS();
+}
+
+bool test_grouped_consistent_begin()
+{
+    const vector<int> groups { 2, 2, 2, 2, 2 };
+    GroupedIterator<vector<int>::const_iterator> iterator(data.begin(), data.end(), groups);
+    auto first = iterator.begin();
+    auto second = iterator.begin();
+    ASSERT_FALSE(first != second);
+    ASSERT_TRUE(++first != second);
+    ASSERT_FALSE(first != ++second);
+    SUCCESS();
+}
+
+bool test_grouped_consistent_end()
+{
+    const vector<int> groups { 2, 2, 2, 2, 2 };
+    GroupedIterator<vector<int>::const_iterator> iterator(data.begin(), data.end(), groups);
+    ASSERT_SAME(iterator.end(), iterator.end());
+    auto it = iterator.begin();
+    advance(it, 5);
+    ASSERT_SAME(it, iterator.end());
+    SUCCESS();
+}
+
+bool test_grouped_empty()
+{
+    GroupedIterator<vector<int>::const_iterator> iterator(data.begin(), data.begin(), std::vector<int>());
+    ASSERT_SAME(iterator.begin(), iterator.end());
+    SUCCESS();
+}
+
+bool test_groupedfunc_simple()
+{
+    unordered_set<int> groups { 3, 5, 8 };
+    vector<int> values(data);
+    GroupedIterator<vector<int>::iterator> iterator = grouped<vector<int>>(
+            values, [&groups](int value) { return groups.find(value) != groups.end(); });
+    vector<vector<int>> expected {
+        { 0, 1, 2, 3 },
+        { 4, 5 },
+        { 6, 7, 8 },
+        { 9 },
+    };
+    auto itA1 = iterator.begin();
+    auto itA2 = expected.begin();
+    while (itA1 != iterator.end() || itA2 != expected.end()) {
+        auto itB1 = (*itA1).begin();
+        auto itB2 = itA2->begin();
+        while (itB1 != (*itA1).end() || itB2 != itA2->end()) {
+            ASSERT_SAME(*itB1, *itB2);
+            ++itB1, ++itB2;
+        }
+        ASSERT_FALSE(itB1 != (*itA1).end());
+        ASSERT_TRUE(itB2 == itA2->end());
+        ++itA1, ++itA2;
+    }
+    ASSERT_FALSE(itA1 != iterator.end());
+    ASSERT_TRUE(itA2 == expected.end());
+    SUCCESS();
+}
+
+bool test_groupedfunc_empty()
+{
+    std::vector<int> data;
+    GroupedIterator<vector<int>::iterator> iterator = grouped(data, [](int value) {
+        (void)value;
+        return true;
+    });
+    ASSERT_SAME(iterator.begin(), iterator.end());
+    SUCCESS();
+}
+
+vector<tuple<string, function<bool()>>> tests = {
+    { "range/simple", test_range_simple },
+    { "range/consistent_begin", test_range_consistent_begin },
+    { "range/consistent_end", test_range_consistent_end },
+    { "range/empty", test_range_empty },
+    { "indexed/simple", test_indexed_simple },
+    { "indexed/consistent_begin", test_indexed_consistent_begin },
+    { "indexed/consistent_end", test_indexed_consistent_end },
+    { "indexed/empty", test_indexed_empty },
+    { "shuffled/simple(0)", test_shuffled_simple_0 },
+    { "shuffled/simple(42)", test_shuffled_simple_42 },
+    { "grouped/simple", test_grouped_simple },
+    { "grouped/consistent_begin", test_grouped_consistent_begin },
+    { "grouped/consistent_end", test_grouped_consistent_end },
+    { "grouped/empty", test_grouped_empty },
+    { "groupedfunc/simple", test_groupedfunc_simple },
+    { "groupedfunc/empty", test_groupedfunc_empty },
+};
+
+int main(int argc, char **argv)
+{
+    (void)argc;
+    (void)argv;
+
+    cout << unitbuf;
+
+    uint count = 0;
+    for (auto test : tests) {
+        string name = get<0>(test);
+        cout << "Test '" << name << "' ";
+        bool success = get<1>(test)();
+        if (success)
+            cout << "succeeded" << endl;
+        count += success;
+    }
+
+    cout << count << "/" << tests.size() << " tests succeeded" << endl;
+    return tests.size() - count;
+}
diff --git a/tools/itertest/itertest.pro b/tools/itertest/itertest.pro
new file mode 100644
index 0000000..1965664
--- /dev/null
+++ b/tools/itertest/itertest.pro
@@ -0,0 +1,12 @@
+TEMPLATE = app
+TARGET = itertest
+CONFIG -= qt
+
+INCLUDEPATH += ../../src/common
+
+SOURCES = \
+    itertest.cpp \
+    ../../src/common/itertools.cpp
+
+HEADERS += \
+    ../../src/common/itertools.h