totalngrams: start adding unit tests
diff --git a/pom.xml b/pom.xml
index 06d16eb..54b31bf 100644
--- a/pom.xml
+++ b/pom.xml
@@ -156,5 +156,11 @@
             <artifactId>parallelgzip</artifactId>
             <version>1.0.5</version>
         </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>RELEASE</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 </project>
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diff --git a/src/test/java/org/ids_mannheim/UtilsTest.java b/src/test/java/org/ids_mannheim/UtilsTest.java
new file mode 100644
index 0000000..02b9c04
--- /dev/null
+++ b/src/test/java/org/ids_mannheim/UtilsTest.java
@@ -0,0 +1,22 @@
+package org.ids_mannheim;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class UtilsTest {
+
+    @org.junit.jupiter.api.BeforeEach
+    void setUp() {
+    }
+
+    @Test
+    void randomFoldIsDeterministic() {
+        assertEquals(404783, Utils.getFoldFromTextID("RPO05_JAN.00001", 1000000));
+        assertEquals(404782, Utils.getFoldFromTextID("RPO05_JAN.00002", 1000000));
+        assertEquals(404781, Utils.getFoldFromTextID("RPO05_JAN.00003", 1000000));
+        assertEquals(404753, Utils.getFoldFromTextID("RPO05_JAN.00010", 1000000));
+        assertEquals(936451, Utils.getFoldFromTextID("RPO05_JUN.00001", 1000000));
+        assertEquals(936450, Utils.getFoldFromTextID("RPO05_JUN.00002", 1000000));
+    }
+}
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