diff --git a/.pylintrc b/.pylintrc
new file mode 100644
index 0000000..0f711fa
--- /dev/null
+++ b/.pylintrc
@@ -0,0 +1,3 @@
+[MASTER]
+
+ignore=tests
diff --git a/requirements.txt b/requirements.txt
new file mode 100644
index 0000000..50d7d55
--- /dev/null
+++ b/requirements.txt
@@ -0,0 +1,19 @@
+astroid==2.12.9
+attrs==22.1.0
+coverage==6.4.4
+dill==0.3.5.1
+iniconfig==1.1.1
+isort==5.10.1
+lazy-object-proxy==1.7.1
+mccabe==0.7.0
+packaging==21.3
+platformdirs==2.5.2
+pluggy==1.0.0
+py==1.11.0
+pylint==2.15.2
+pyparsing==3.0.9
+pytest==7.1.3
+tomli==2.0.1
+tomlkit==0.11.4
+typing-extensions==4.3.0
+wrapt==1.14.1
diff --git a/src/tests/__init__.py b/src/tests/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/tests/trie_test.py b/src/tests/trie_test.py
new file mode 100644
index 0000000..dc2fd2c
--- /dev/null
+++ b/src/tests/trie_test.py
@@ -0,0 +1,31 @@
+import unittest
+from trie import Trie
+
+class TestTrie(unittest.TestCase):
+    def setUp(self):
+        """Alustus testejä varten."""
+        self.trie = Trie()
+
+    def test_lisaa(self):
+        self.assertFalse(self.trie.juuri.lapset)
+
+        self.trie.lisaa("AB")
+
+        self.assertTrue("A" in self.trie.juuri.lapset)
+        self.assertFalse("B" in self.trie.juuri.lapset)
+        self.assertEqual(0, self.trie.juuri.lapset["A"].laskuri)
+        self.assertEqual(1, self.trie.juuri.lapset["A"].lapset["B"].laskuri)
+
+        self.trie.lisaa("AB")
+
+        self.assertEqual(2, self.trie.juuri.lapset["A"].lapset["B"].laskuri)
+
+    def test_etsi_seuraavat(self):
+        self.assertFalse(self.trie.etsi_seuraavat("AB"))
+        self.trie.lisaa("ABC")
+        self.trie.lisaa("ABC")
+        self.assertEqual(self.trie.etsi_seuraavat("AB"), [(1, "C")])
+        self.trie.lisaa("ABC")
+        self.trie.lisaa("ABD")
+        self.assertEqual(self.trie.etsi_seuraavat("AB"), [(0.75, "C"), (0.25, "D")])
+        self.assertEqual(self.trie.etsi_seuraavat("AB"), [(0.75, "C"), (0.25, "D")])
diff --git a/src/trie.py b/src/trie.py
index 717117c..3cf8a37 100644
--- a/src/trie.py
+++ b/src/trie.py
@@ -1,5 +1,5 @@
 """Markovin ketjuille tarkoitettu trie-tietorakenteen implementaatio.
-import Trie
+from trie import Trie
 """
 
 class TrieSolmu: # pylint: disable=too-few-public-methods