diff --git a/src/test/java/org/nwapw/abacus/tests/TokenizerTests.java b/src/test/java/org/nwapw/abacus/tests/TokenizerTests.java
index 3a66581..ecdda23 100644
--- a/src/test/java/org/nwapw/abacus/tests/TokenizerTests.java
+++ b/src/test/java/org/nwapw/abacus/tests/TokenizerTests.java
@@ -1,50 +1,124 @@
 package org.nwapw.abacus.tests;
 
 import org.junit.Assert;
+import org.junit.BeforeClass;
 import org.junit.Test;
+import org.nwapw.abacus.Abacus;
+import org.nwapw.abacus.function.Function;
+import org.nwapw.abacus.function.Operator;
+import org.nwapw.abacus.function.OperatorAssociativity;
+import org.nwapw.abacus.function.OperatorType;
 import org.nwapw.abacus.lexing.pattern.Match;
+import org.nwapw.abacus.number.NumberInterface;
 import org.nwapw.abacus.parsing.LexerTokenizer;
+import org.nwapw.abacus.plugin.Plugin;
 import org.nwapw.abacus.tree.TokenType;
 
 import java.util.List;
 
 public class TokenizerTests {
 
-    private LexerTokenizer lexerTokenizer = new LexerTokenizer();
+    private static Abacus abacus = new Abacus();
+    private static LexerTokenizer lexerTokenizer = new LexerTokenizer();
+    private static Function subtractFunction = new Function() {
+        @Override
+        protected boolean matchesParams(NumberInterface[] params) {
+            return params.length == 2;
+        }
 
-    @Test
-    public void testInteger(){
-        List<Match<TokenType>> tokens = lexerTokenizer.tokenizeString("11");
-        Assert.assertNotNull(tokens);
-        Assert.assertEquals(tokens.size(), 1);
-        Assert.assertEquals(tokens.get(0).getType(), TokenType.NUM);
+        @Override
+        protected NumberInterface applyInternal(NumberInterface[] params) {
+            return params[0].subtract(params[1]);
+        }
+    };
+    private static Plugin testPlugin = new Plugin(abacus.getPluginManager()) {
+        @Override
+        public void onEnable() {
+            registerOperator("+", new Operator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX,
+                    0, subtractFunction));
+            registerOperator("-", new Operator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX,
+                    0, subtractFunction));
+            registerFunction("subtract", subtractFunction);
+        }
+
+        @Override
+        public void onDisable() {
+
+        }
+    };
+
+    private static void assertTokensMatch(List<Match<TokenType>> tokenList, TokenType[] expectedTypes) {
+        Assert.assertNotNull(tokenList);
+        Assert.assertEquals(tokenList.size(), expectedTypes.length);
+        for (int i = 0; i < expectedTypes.length; i++) {
+            Assert.assertEquals(expectedTypes[i], tokenList.get(i).getType());
+        }
+    }
+
+    @BeforeClass
+    public static void prepareTests() {
+        abacus.getPluginManager().addListener(lexerTokenizer);
+        abacus.getPluginManager().addInstantiated(testPlugin);
+        abacus.getPluginManager().load();
     }
 
     @Test
-    public void testLeadingZeroDecimal(){
-        List<Match<TokenType>> tokens = lexerTokenizer.tokenizeString("0.1");
-        Assert.assertNotNull(tokens);
-        Assert.assertEquals(tokens.size(), 1);
-        Assert.assertEquals(tokens.get(0).getType(), TokenType.NUM);
+    public void testInteger() {
+        assertTokensMatch(lexerTokenizer.tokenizeString("11"), new TokenType[]{ TokenType.NUM } );
     }
 
     @Test
-    public void testNonLeadingDecimal(){
-        List<Match<TokenType>> tokens = lexerTokenizer.tokenizeString(".1");
-        Assert.assertNotNull(tokens);
-        Assert.assertEquals(tokens.size(), 1);
-        Assert.assertEquals(tokens.get(0).getType(), TokenType.NUM);
+    public void testLeadingZeroDecimal() {
+        assertTokensMatch(lexerTokenizer.tokenizeString("0.1"), new TokenType[]{ TokenType.NUM } );
     }
 
     @Test
-    public void testSimpleChars(){
-        List<Match<TokenType>> tokens = lexerTokenizer.tokenizeString("( ,)");
-        Assert.assertNotNull(tokens);
-        Assert.assertEquals(tokens.size(), 4);
-        Assert.assertEquals(tokens.get(0).getType(), TokenType.OPEN_PARENTH);
-        Assert.assertEquals(tokens.get(1).getType(), TokenType.WHITESPACE);
-        Assert.assertEquals(tokens.get(2).getType(), TokenType.COMMA);
-        Assert.assertEquals(tokens.get(3).getType(), TokenType.CLOSE_PARENTH);
+    public void testNonLeadingDecimal() {
+        assertTokensMatch(lexerTokenizer.tokenizeString(".1"), new TokenType[]{ TokenType.NUM } );
+    }
+
+    @Test
+    public void testSimpleChars() {
+        TokenType[] types = {
+                TokenType.OPEN_PARENTH,
+                TokenType.WHITESPACE,
+                TokenType.COMMA,
+                TokenType.CLOSE_PARENTH
+        };
+        assertTokensMatch(lexerTokenizer.tokenizeString("( ,)"), types);
+    }
+
+    @Test
+    public void testFunctionParsing() {
+        TokenType[] types = {
+                TokenType.FUNCTION,
+                TokenType.OPEN_PARENTH,
+                TokenType.NUM,
+                TokenType.COMMA,
+                TokenType.NUM,
+                TokenType.CLOSE_PARENTH
+        };
+        assertTokensMatch(lexerTokenizer.tokenizeString("subtract(1,2)"), types);
+    }
+
+    @Test
+    public void testOperatorParsing(){
+        TokenType[] types = {
+                TokenType.NUM,
+                TokenType.OP,
+                TokenType.NUM
+        };
+        assertTokensMatch(lexerTokenizer.tokenizeString("1-1"), types);
+    }
+
+    @Test
+    public void testSanitizedOperators(){
+        TokenType[] types = {
+                TokenType.NUM,
+                TokenType.OP,
+                TokenType.NUM
+        };
+        assertTokensMatch(lexerTokenizer.tokenizeString("1+1"), types);
     }
 
 }