diff --git a/src/main/kotlin/function/builtin/APPLY.java b/src/main/kotlin/function/builtin/APPLY.java
deleted file mode 100644
index c2b35a8..0000000
--- a/src/main/kotlin/function/builtin/APPLY.java
+++ /dev/null
@@ -1,39 +0,0 @@
-package function.builtin;
-
-import function.ArgumentValidator;
-import function.FunctionNames;
-import function.LispFunction;
-import sexpression.Cons;
-import sexpression.SExpression;
-import table.FunctionTable;
-
-import static function.builtin.Eval.applyFunction;
-import static function.builtin.Eval.lookupFunctionOrLambda;
-
-@FunctionNames({ "APPLY" })
-public class APPLY extends LispFunction {
-
-    public static SExpression apply(Cons argumentList) {
-        return FunctionTable.INSTANCE.lookupFunction("APPLY").call(argumentList);
-    }
-
-    private ArgumentValidator argumentValidator;
-
-    public APPLY(String name) {
-        this.argumentValidator = new ArgumentValidator(name);
-        this.argumentValidator.setExactNumberOfArguments(2);
-        this.argumentValidator.setTrailingArgumentExpectedType(Cons.class);
-    }
-
-    @Override
-    public SExpression call(Cons argumentList) {
-        argumentValidator.validate(argumentList);
-
-        Cons rest = (Cons) argumentList.getRest();
-        Cons functionArguments = (Cons) rest.getFirst();
-        SExpression functionName = argumentList.getFirst();
-        LispFunction function = lookupFunctionOrLambda(functionName);
-
-        return applyFunction(function, functionArguments);
-    }
-}
diff --git a/src/main/kotlin/function/builtin/Apply.kt b/src/main/kotlin/function/builtin/Apply.kt
new file mode 100644
index 0000000..afe7766
--- /dev/null
+++ b/src/main/kotlin/function/builtin/Apply.kt
@@ -0,0 +1,38 @@
+package function.builtin
+
+import function.ArgumentValidator
+import function.FunctionNames
+import function.LispFunction
+import sexpression.Cons
+import sexpression.SExpression
+import table.FunctionTable
+
+import function.builtin.Eval.Companion.applyFunction
+import function.builtin.Eval.Companion.lookupFunctionOrLambda
+
+@FunctionNames("APPLY")
+class Apply(name: String) : LispFunction() {
+
+    private val argumentValidator: ArgumentValidator = ArgumentValidator(name).apply {
+        setExactNumberOfArguments(2)
+        setTrailingArgumentExpectedType(Cons::class.java)
+    }
+
+    override fun call(argumentList: Cons): SExpression {
+        argumentValidator.validate(argumentList)
+
+        val rest = argumentList.rest as Cons
+        val functionArguments = rest.first as Cons
+        val functionName = argumentList.first
+        val function = lookupFunctionOrLambda(functionName)
+
+        return applyFunction(function, functionArguments)
+    }
+
+    companion object {
+
+        fun apply(argumentList: Cons): SExpression {
+            return FunctionTable.lookupFunction("APPLY")!!.call(argumentList)
+        }
+    }
+}
diff --git a/src/main/kotlin/function/builtin/FUNCALL.java b/src/main/kotlin/function/builtin/FUNCALL.java
deleted file mode 100644
index c21194a..0000000
--- a/src/main/kotlin/function/builtin/FUNCALL.java
+++ /dev/null
@@ -1,29 +0,0 @@
-package function.builtin;
-
-import function.ArgumentValidator;
-import function.FunctionNames;
-import function.LispFunction;
-import sexpression.Cons;
-import sexpression.SExpression;
-
-import static function.builtin.APPLY.apply;
-import static function.builtin.cons.LIST.makeList;
-
-@FunctionNames({ "FUNCALL", "CALL" })
-public class FUNCALL extends LispFunction {
-
-    private ArgumentValidator argumentValidator;
-
-    public FUNCALL(String name) {
-        this.argumentValidator = new ArgumentValidator(name);
-        this.argumentValidator.setMinimumNumberOfArguments(1);
-    }
-
-    @Override
-    public SExpression call(Cons argumentList) {
-        argumentValidator.validate(argumentList);
-        Cons applyArgs = new Cons(argumentList.getFirst(), makeList(argumentList.getRest()));
-
-        return apply(applyArgs);
-    }
-}
diff --git a/src/main/kotlin/function/builtin/Funcall.kt b/src/main/kotlin/function/builtin/Funcall.kt
new file mode 100644
index 0000000..aaa9b48
--- /dev/null
+++ b/src/main/kotlin/function/builtin/Funcall.kt
@@ -0,0 +1,24 @@
+package function.builtin
+
+import function.ArgumentValidator
+import function.FunctionNames
+import function.LispFunction
+import function.builtin.Apply.Companion.apply
+import function.builtin.cons.LIST.makeList
+import sexpression.Cons
+import sexpression.SExpression
+
+@FunctionNames("FUNCALL", "CALL")
+class Funcall(name: String) : LispFunction() {
+
+    private val argumentValidator: ArgumentValidator = ArgumentValidator(name).apply {
+        setMinimumNumberOfArguments(1)
+    }
+
+    override fun call(argumentList: Cons): SExpression {
+        argumentValidator.validate(argumentList)
+        val applyArgs = Cons(argumentList.first, makeList(argumentList.rest))
+
+        return apply(applyArgs)
+    }
+}
diff --git a/src/main/kotlin/function/builtin/GENSYM.java b/src/main/kotlin/function/builtin/GENSYM.java
deleted file mode 100644
index a07d74d..0000000
--- a/src/main/kotlin/function/builtin/GENSYM.java
+++ /dev/null
@@ -1,42 +0,0 @@
-package function.builtin;
-
-import function.ArgumentValidator;
-import function.FunctionNames;
-import function.LispFunction;
-import sexpression.Cons;
-import sexpression.SExpression;
-import sexpression.Symbol;
-
-import java.math.BigInteger;
-
-@FunctionNames({ "GENSYM" })
-public class GENSYM extends LispFunction {
-
-    public static final String GENSYM_PREFIX = "#G";
-
-    private static BigInteger counter = BigInteger.ZERO;
-
-    private static Symbol generateSymbol() {
-        incrementCounter();
-
-        return new Symbol(GENSYM_PREFIX + counter);
-    }
-
-    private static void incrementCounter() {
-        counter = counter.add(BigInteger.ONE);
-    }
-
-    private ArgumentValidator argumentValidator;
-
-    public GENSYM(String name) {
-        this.argumentValidator = new ArgumentValidator(name);
-        this.argumentValidator.setMaximumNumberOfArguments(0);
-    }
-
-    @Override
-    public SExpression call(Cons argumentList) {
-        argumentValidator.validate(argumentList);
-
-        return generateSymbol();
-    }
-}
diff --git a/src/main/kotlin/function/builtin/Gensym.kt b/src/main/kotlin/function/builtin/Gensym.kt
new file mode 100644
index 0000000..434c266
--- /dev/null
+++ b/src/main/kotlin/function/builtin/Gensym.kt
@@ -0,0 +1,41 @@
+package function.builtin
+
+import function.ArgumentValidator
+import function.FunctionNames
+import function.LispFunction
+import sexpression.Cons
+import sexpression.SExpression
+import sexpression.Symbol
+import java.math.BigInteger.ONE
+import java.math.BigInteger.ZERO
+
+@FunctionNames("GENSYM")
+class Gensym(name: String) : LispFunction() {
+
+    private val argumentValidator: ArgumentValidator = ArgumentValidator(name).apply {
+        setMaximumNumberOfArguments(0)
+    }
+
+    override fun call(argumentList: Cons): SExpression {
+        argumentValidator.validate(argumentList)
+
+        return generateSymbol()
+    }
+
+    companion object {
+
+        const val GENSYM_PREFIX = "#G"
+
+        private var counter = ZERO
+
+        private fun generateSymbol(): Symbol {
+            incrementCounter()
+
+            return Symbol(GENSYM_PREFIX + counter)
+        }
+
+        private fun incrementCounter() {
+            counter = counter.add(ONE)
+        }
+    }
+}
diff --git a/src/main/kotlin/function/builtin/SYMBOLS.java b/src/main/kotlin/function/builtin/SYMBOLS.java
deleted file mode 100644
index 834fb86..0000000
--- a/src/main/kotlin/function/builtin/SYMBOLS.java
+++ /dev/null
@@ -1,28 +0,0 @@
-package function.builtin;
-
-import function.ArgumentValidator;
-import function.FunctionNames;
-import function.LispFunction;
-import sexpression.Cons;
-import sexpression.SExpression;
-import table.ExecutionContext;
-
-@FunctionNames({ "SYMBOLS" })
-public class SYMBOLS extends LispFunction {
-
-    private ArgumentValidator argumentValidator;
-    private ExecutionContext executionContext;
-
-    public SYMBOLS(String name) {
-        this.argumentValidator = new ArgumentValidator(name);
-        this.argumentValidator.setExactNumberOfArguments(0);
-        this.executionContext = ExecutionContext.INSTANCE;
-    }
-
-    @Override
-    public SExpression call(Cons argumentList) {
-        argumentValidator.validate(argumentList);
-
-        return executionContext.toList();
-    }
-}
diff --git a/src/main/kotlin/function/builtin/SYMBOL_FUNCTION.java b/src/main/kotlin/function/builtin/SYMBOL_FUNCTION.java
deleted file mode 100644
index 69ecc57..0000000
--- a/src/main/kotlin/function/builtin/SYMBOL_FUNCTION.java
+++ /dev/null
@@ -1,63 +0,0 @@
-package function.builtin;
-
-import error.LispException;
-import function.ArgumentValidator;
-import function.FunctionNames;
-import function.LispFunction;
-import function.LispSpecialFunction;
-import function.UserDefinedFunction;
-import sexpression.Cons;
-import sexpression.SExpression;
-import sexpression.Symbol;
-import table.FunctionTable;
-
-import static java.text.MessageFormat.format;
-
-@FunctionNames({ "SYMBOL-FUNCTION" })
-public class SYMBOL_FUNCTION extends LispFunction {
-
-    private ArgumentValidator argumentValidator;
-
-    public SYMBOL_FUNCTION(String name) {
-        this.argumentValidator = new ArgumentValidator(name);
-        this.argumentValidator.setExactNumberOfArguments(1);
-        this.argumentValidator.setEveryArgumentExpectedType(Symbol.class);
-    }
-
-    @Override
-    public SExpression call(Cons argumentList) {
-        argumentValidator.validate(argumentList);
-
-        SExpression symbol = argumentList.getFirst();
-        LispFunction function = FunctionTable.INSTANCE.lookupFunction(symbol.toString());
-
-        if (function != null)
-            return createRepresentation(symbol, function);
-
-        throw new UndefinedSymbolFunctionException(symbol);
-    }
-
-    private SExpression createRepresentation(SExpression symbol, LispFunction function) {
-        if (function instanceof UserDefinedFunction)
-            return ((UserDefinedFunction) function).getLambdaExpression();
-
-        String typeIndicator = function instanceof LispSpecialFunction ? "SPECIAL-FUNCTION" : "FUNCTION";
-
-        return new Symbol(format("#<{0} {1}>", typeIndicator, symbol));
-    }
-
-    public static class UndefinedSymbolFunctionException extends LispException {
-
-        private static final long serialVersionUID = 1L;
-        private SExpression function;
-
-        public UndefinedSymbolFunctionException(SExpression function) {
-            this.function = function;
-        }
-
-        @Override
-        public String getMessage() {
-            return format("SYMBOL-FUNCTION: undefined function: {0}", function);
-        }
-    }
-}
diff --git a/src/main/kotlin/function/builtin/SymbolFunction.kt b/src/main/kotlin/function/builtin/SymbolFunction.kt
new file mode 100644
index 0000000..ae49af7
--- /dev/null
+++ b/src/main/kotlin/function/builtin/SymbolFunction.kt
@@ -0,0 +1,47 @@
+package function.builtin
+
+import error.LispException
+import function.ArgumentValidator
+import function.FunctionNames
+import function.LispFunction
+import function.LispSpecialFunction
+import function.UserDefinedFunction
+import sexpression.Cons
+import sexpression.SExpression
+import sexpression.Symbol
+import table.FunctionTable
+
+@FunctionNames("SYMBOL-FUNCTION")
+class SymbolFunction(name: String) : LispFunction() {
+
+    private val argumentValidator: ArgumentValidator = ArgumentValidator(name).apply {
+        setExactNumberOfArguments(1)
+        setEveryArgumentExpectedType(Symbol::class.java)
+    }
+
+    override fun call(argumentList: Cons): SExpression {
+        argumentValidator.validate(argumentList)
+
+        val symbol = argumentList.first
+        val function = FunctionTable.lookupFunction(symbol.toString())
+
+        if (function != null)
+            return createRepresentation(symbol, function)
+
+        throw UndefinedSymbolFunctionException(symbol)
+    }
+
+    private fun createRepresentation(symbol: SExpression, function: LispFunction): SExpression {
+        if (function is UserDefinedFunction)
+            return function.lambdaExpression
+
+        val typeIndicator = if (function is LispSpecialFunction) "SPECIAL-FUNCTION" else "FUNCTION"
+
+        return Symbol("#<$typeIndicator $symbol>")
+    }
+
+    class UndefinedSymbolFunctionException(function: SExpression) : LispException() {
+
+        override val message = "SYMBOL-FUNCTION: undefined function: $function"
+    }
+}
diff --git a/src/main/kotlin/function/builtin/Symbols.kt b/src/main/kotlin/function/builtin/Symbols.kt
new file mode 100644
index 0000000..6f6fd60
--- /dev/null
+++ b/src/main/kotlin/function/builtin/Symbols.kt
@@ -0,0 +1,22 @@
+package function.builtin
+
+import function.ArgumentValidator
+import function.FunctionNames
+import function.LispFunction
+import sexpression.Cons
+import sexpression.SExpression
+import table.ExecutionContext
+
+@FunctionNames("SYMBOLS")
+class Symbols(name: String) : LispFunction() {
+
+    private val argumentValidator: ArgumentValidator = ArgumentValidator(name).apply {
+        setExactNumberOfArguments(0)
+    }
+
+    override fun call(argumentList: Cons): SExpression {
+        argumentValidator.validate(argumentList)
+
+        return ExecutionContext.toList()
+    }
+}
diff --git a/src/main/kotlin/function/builtin/predicate/GENSYM_EQUAL.java b/src/main/kotlin/function/builtin/predicate/GENSYM_EQUAL.java
deleted file mode 100644
index d87f352..0000000
--- a/src/main/kotlin/function/builtin/predicate/GENSYM_EQUAL.java
+++ /dev/null
@@ -1,100 +0,0 @@
-package function.builtin.predicate;
-
-import function.ArgumentValidator;
-import function.FunctionNames;
-import function.LispFunction;
-import sexpression.Cons;
-import sexpression.Nil;
-import sexpression.SExpression;
-import sexpression.Symbol;
-
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Map.Entry;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
-
-import static function.builtin.GENSYM.GENSYM_PREFIX;
-
-@FunctionNames({ "GENSYM-EQUAL", "GENSYM-EQUAL?" })
-public class GENSYM_EQUAL extends LispFunction {
-
-    private ArgumentValidator argumentValidator;
-
-    public GENSYM_EQUAL(String name) {
-        this.argumentValidator = new ArgumentValidator(name);
-        this.argumentValidator.setExactNumberOfArguments(2);
-    }
-
-    @Override
-    public SExpression call(Cons argumentList) {
-        argumentValidator.validate(argumentList);
-
-        Cons rest = (Cons) argumentList.getRest();
-        SExpression firstArgument = argumentList.getFirst();
-        SExpression secondArgument = rest.getFirst();
-
-        return gensymEqual(firstArgument, secondArgument);
-    }
-
-    private SExpression gensymEqual(SExpression firstArgument, SExpression secondArgument) {
-        String firstEqualized = equalizeGensyms(firstArgument);
-        String secondEqualized = equalizeGensyms(secondArgument);
-
-        return firstEqualized.equals(secondEqualized) ? Symbol.Companion.getT() : Nil.INSTANCE;
-    }
-
-    private String equalizeGensyms(SExpression expression) {
-        GensymEqualizer equalizer = new GensymEqualizer(expression.toString());
-
-        return equalizer.equalize();
-    }
-
-    private static class GensymEqualizer {
-
-        private static final String GENSYM_REGEX = Pattern.quote(GENSYM_PREFIX) + "[0-9]+";
-
-        Map<String, String> gensymAliases;
-        Matcher matcher;
-        String expression;
-        int counter;
-
-        public GensymEqualizer(String expression) {
-            this.gensymAliases = new HashMap<>();
-            this.matcher = Pattern.compile(GENSYM_REGEX).matcher(expression);
-            this.expression = expression;
-            this.counter = 0;
-        }
-
-        public String equalize() {
-            createGensymAliases();
-
-            return equalizeGensyms();
-        }
-
-        private void createGensymAliases() {
-            while (matcher.find())
-                createAliasForGensym();
-        }
-
-        private void createAliasForGensym() {
-            String gensym = matcher.group();
-
-            if (isNewGensym(gensym))
-                gensymAliases.put(gensym, GENSYM_PREFIX + (counter++));
-        }
-
-        private boolean isNewGensym(String gensym) {
-            return !gensymAliases.containsKey(gensym);
-        }
-
-        private String equalizeGensyms() {
-            String equalizedExpression = expression;
-
-            for (Entry<String, String> entry : gensymAliases.entrySet())
-                equalizedExpression = equalizedExpression.replace(entry.getKey(), entry.getValue());
-
-            return equalizedExpression;
-        }
-    }
-}
diff --git a/src/main/kotlin/function/builtin/predicate/GensymEqual.kt b/src/main/kotlin/function/builtin/predicate/GensymEqual.kt
new file mode 100644
index 0000000..93d3a8d
--- /dev/null
+++ b/src/main/kotlin/function/builtin/predicate/GensymEqual.kt
@@ -0,0 +1,82 @@
+package function.builtin.predicate
+
+import function.ArgumentValidator
+import function.FunctionNames
+import function.LispFunction
+import function.builtin.Gensym.Companion.GENSYM_PREFIX
+import sexpression.Cons
+import sexpression.Nil
+import sexpression.SExpression
+import sexpression.Symbol
+import java.util.regex.Pattern
+
+@FunctionNames("GENSYM-EQUAL", "GENSYM-EQUAL?")
+class GensymEqual(name: String) : LispFunction() {
+
+    private val argumentValidator: ArgumentValidator = ArgumentValidator(name).apply {
+        setExactNumberOfArguments(2)
+    }
+
+    override fun call(argumentList: Cons): SExpression {
+        argumentValidator.validate(argumentList)
+
+        val rest = argumentList.rest as Cons
+        val firstArgument = argumentList.first
+        val secondArgument = rest.first
+
+        return gensymEqual(firstArgument, secondArgument)
+    }
+
+    private fun gensymEqual(firstArgument: SExpression, secondArgument: SExpression): SExpression {
+        val firstEqualized = equalizeGensyms(firstArgument)
+        val secondEqualized = equalizeGensyms(secondArgument)
+
+        return if (firstEqualized == secondEqualized) Symbol.T else Nil
+    }
+
+    private fun equalizeGensyms(expression: SExpression) =
+        GensymEqualizer(expression.toString()).equalize()
+
+    private class GensymEqualizer(internal var expression: String) {
+
+        internal val gensymAliases = mutableMapOf<String, String>()
+        internal var matcher = Pattern.compile(GENSYM_REGEX).matcher(expression)
+        internal var counter: Int = 0
+
+        fun equalize(): String {
+            createGensymAliases()
+
+            return equalizeGensyms()
+        }
+
+        private fun createGensymAliases() {
+            while (matcher.find())
+                createAliasForGensym()
+        }
+
+        private fun createAliasForGensym() {
+            val gensym = matcher.group()
+
+            if (isNewGensym(gensym))
+                gensymAliases[gensym] = GENSYM_PREFIX + counter++
+        }
+
+        private fun isNewGensym(gensym: String): Boolean {
+            return !gensymAliases.containsKey(gensym)
+        }
+
+        private fun equalizeGensyms(): String {
+            var equalizedExpression = expression
+
+            for ((key, value) in gensymAliases)
+                equalizedExpression = equalizedExpression.replace(key, value)
+
+            return equalizedExpression
+        }
+
+        companion object {
+
+            private val GENSYM_REGEX = Pattern.quote(GENSYM_PREFIX) + "[0-9]+"
+        }
+    }
+}
diff --git a/src/test/kotlin/function/builtin/APPLYTest.java b/src/test/kotlin/function/builtin/APPLYTest.java
deleted file mode 100644
index 561c7b4..0000000
--- a/src/test/kotlin/function/builtin/APPLYTest.java
+++ /dev/null
@@ -1,78 +0,0 @@
-package function.builtin;
-
-import function.ArgumentValidator.BadArgumentTypeException;
-import function.ArgumentValidator.DottedArgumentListException;
-import function.ArgumentValidator.TooFewArgumentsException;
-import function.ArgumentValidator.TooManyArgumentsException;
-import function.builtin.Eval.UndefinedFunctionException;
-import org.junit.Test;
-import sexpression.Cons;
-import testutil.SymbolAndFunctionCleaner;
-
-import static function.builtin.APPLY.apply;
-import static testutil.TestUtilities.assertSExpressionsMatch;
-import static testutil.TestUtilities.evaluateString;
-import static testutil.TestUtilities.parseString;
-
-public class APPLYTest extends SymbolAndFunctionCleaner {
-
-    @Test
-    public void applyWithSymbol() {
-        String input = "(apply '+ '(1 2 3))";
-
-        assertSExpressionsMatch(parseString("6"), evaluateString(input));
-    }
-
-    @Test
-    public void applyWithLambdaExpression() {
-        String input = "(apply (lambda (x) (+ x 1)) '(25))";
-
-        assertSExpressionsMatch(parseString("26"), evaluateString(input));
-    }
-
-    @Test
-    public void applyWithQuotedLambdaExpression() {
-        String input = "(apply '(lambda (x) (+ x 1)) '(25))";
-
-        assertSExpressionsMatch(parseString("26"), evaluateString(input));
-    }
-
-    @Test
-    public void staticApplyCall() {
-        String argumentList = "(+ (25 10))";
-        Cons parsedArgumentList = (Cons) parseString(argumentList);
-
-        assertSExpressionsMatch(parseString("35"), apply(parsedArgumentList));
-    }
-
-    @Test(expected = UndefinedFunctionException.class)
-    public void applyWithUndefinedFunction() {
-        evaluateString("(apply 'f '(1 2 3))");
-    }
-
-    @Test(expected = BadArgumentTypeException.class)
-    public void applyWithNonListSecondArgument() {
-        evaluateString("(apply '+ '2)");
-    }
-
-    @Test(expected = TooManyArgumentsException.class)
-    public void applyWithTooManyArguments() {
-        evaluateString("(apply '1 '2 '3)");
-    }
-
-    @Test(expected = TooFewArgumentsException.class)
-    public void applyWithTooFewArguments() {
-        evaluateString("(apply '1)");
-    }
-
-    @Test(expected = DottedArgumentListException.class)
-    public void applyWithDottedArgumentList_ThrowsException() {
-        evaluateString("(apply 'apply (cons 'T 'T))");
-    }
-
-    @Test
-    public void applyWithMacro() {
-        evaluateString("(defmacro m (x) `(+ 2 ,x))");
-        assertSExpressionsMatch(parseString("27"), evaluateString("(apply 'm '(25))"));
-    }
-}
diff --git a/src/test/kotlin/function/builtin/ApplyTest.kt b/src/test/kotlin/function/builtin/ApplyTest.kt
new file mode 100644
index 0000000..058a3ce
--- /dev/null
+++ b/src/test/kotlin/function/builtin/ApplyTest.kt
@@ -0,0 +1,90 @@
+package function.builtin
+
+import function.ArgumentValidator.BadArgumentTypeException
+import function.ArgumentValidator.DottedArgumentListException
+import function.ArgumentValidator.TooFewArgumentsException
+import function.ArgumentValidator.TooManyArgumentsException
+import function.builtin.Apply.Companion.apply
+import function.builtin.Eval.UndefinedFunctionException
+import org.junit.jupiter.api.Assertions.assertThrows
+import org.junit.jupiter.api.Test
+import sexpression.Cons
+import testutil.LispTestInstance
+import testutil.SymbolAndFunctionCleaner
+import testutil.TestUtilities.assertSExpressionsMatch
+import testutil.TestUtilities.evaluateString
+import testutil.TestUtilities.parseString
+
+@LispTestInstance
+class ApplyTest : SymbolAndFunctionCleaner() {
+
+    @Test
+    fun applyWithSymbol() {
+        val input = "(apply '+ '(1 2 3))"
+
+        assertSExpressionsMatch(parseString("6"), evaluateString(input))
+    }
+
+    @Test
+    fun applyWithLambdaExpression() {
+        val input = "(apply (lambda (x) (+ x 1)) '(25))"
+
+        assertSExpressionsMatch(parseString("26"), evaluateString(input))
+    }
+
+    @Test
+    fun applyWithQuotedLambdaExpression() {
+        val input = "(apply '(lambda (x) (+ x 1)) '(25))"
+
+        assertSExpressionsMatch(parseString("26"), evaluateString(input))
+    }
+
+    @Test
+    fun staticApplyCall() {
+        val argumentList = "(+ (25 10))"
+        val parsedArgumentList = parseString(argumentList) as Cons
+
+        assertSExpressionsMatch(parseString("35"), apply(parsedArgumentList))
+    }
+
+    @Test
+    fun applyWithUndefinedFunction() {
+        assertThrows(UndefinedFunctionException::class.java) {
+            evaluateString("(apply 'f '(1 2 3))")
+        }
+    }
+
+    @Test
+    fun applyWithNonListSecondArgument() {
+        assertThrows(BadArgumentTypeException::class.java) {
+            evaluateString("(apply '+ '2)")
+        }
+    }
+
+    @Test
+    fun applyWithTooManyArguments() {
+        assertThrows(TooManyArgumentsException::class.java) {
+            evaluateString("(apply '1 '2 '3)")
+        }
+    }
+
+    @Test
+    fun applyWithTooFewArguments() {
+        assertThrows(TooFewArgumentsException::class.java) {
+            evaluateString("(apply '1)")
+        }
+    }
+
+    @Test
+    fun applyWithDottedArgumentList_ThrowsException() {
+        assertThrows(DottedArgumentListException::class.java) {
+            evaluateString("(apply 'apply (cons 'T 'T))")
+        }
+    }
+
+    @Test
+    fun applyWithMacro() {
+        evaluateString("(defmacro m (x) `(+ 2 ,x))")
+        assertSExpressionsMatch(parseString("27"), evaluateString("(apply 'm '(25))"))
+    }
+}
diff --git a/src/test/kotlin/function/builtin/FUNCALLTest.java b/src/test/kotlin/function/builtin/FUNCALLTest.java
deleted file mode 100644
index 5d2d7b1..0000000
--- a/src/test/kotlin/function/builtin/FUNCALLTest.java
+++ /dev/null
@@ -1,40 +0,0 @@
-package function.builtin;
-
-import function.ArgumentValidator.TooFewArgumentsException;
-import org.junit.Test;
-import testutil.SymbolAndFunctionCleaner;
-
-import static testutil.TestUtilities.assertSExpressionsMatch;
-import static testutil.TestUtilities.evaluateString;
-import static testutil.TestUtilities.parseString;
-
-public class FUNCALLTest extends SymbolAndFunctionCleaner {
-
-    @Test
-    public void funcallWithNumbers() {
-        String input = "(funcall '+ 1 2 3)";
-
-        assertSExpressionsMatch(parseString("6"), evaluateString(input));
-    }
-
-    @Test
-    public void callWithNumbers() {
-        String input = "(call '+ 1 2 3)";
-
-        assertSExpressionsMatch(parseString("6"), evaluateString(input));
-    }
-
-    @Test
-    public void funcallWithUserDefinedFunction() {
-        String defineUserFunction = "(defun x (n m) (+ n m))";
-        String input = "(funcall 'x 2 30)";
-
-        evaluateString(defineUserFunction);
-        assertSExpressionsMatch(parseString("32"), evaluateString(input));
-    }
-
-    @Test(expected = TooFewArgumentsException.class)
-    public void funcallWithTooFewArguments() {
-        evaluateString("(funcall)");
-    }
-}
diff --git a/src/test/kotlin/function/builtin/FuncallTest.kt b/src/test/kotlin/function/builtin/FuncallTest.kt
new file mode 100644
index 0000000..227d539
--- /dev/null
+++ b/src/test/kotlin/function/builtin/FuncallTest.kt
@@ -0,0 +1,44 @@
+package function.builtin
+
+import function.ArgumentValidator.TooFewArgumentsException
+import org.junit.jupiter.api.Assertions.assertThrows
+import org.junit.jupiter.api.Test
+import testutil.LispTestInstance
+import testutil.SymbolAndFunctionCleaner
+import testutil.TestUtilities.assertSExpressionsMatch
+import testutil.TestUtilities.evaluateString
+import testutil.TestUtilities.parseString
+
+@LispTestInstance
+class FuncallTest : SymbolAndFunctionCleaner() {
+
+    @Test
+    fun funcallWithNumbers() {
+        val input = "(funcall '+ 1 2 3)"
+
+        assertSExpressionsMatch(parseString("6"), evaluateString(input))
+    }
+
+    @Test
+    fun callWithNumbers() {
+        val input = "(call '+ 1 2 3)"
+
+        assertSExpressionsMatch(parseString("6"), evaluateString(input))
+    }
+
+    @Test
+    fun funcallWithUserDefinedFunction() {
+        val defineUserFunction = "(defun x (n m) (+ n m))"
+        val input = "(funcall 'x 2 30)"
+
+        evaluateString(defineUserFunction)
+        assertSExpressionsMatch(parseString("32"), evaluateString(input))
+    }
+
+    @Test
+    fun funcallWithTooFewArguments() {
+        assertThrows(TooFewArgumentsException::class.java) {
+            evaluateString("(funcall)")
+        }
+    }
+}
diff --git a/src/test/kotlin/function/builtin/GENSYMTest.java b/src/test/kotlin/function/builtin/GENSYMTest.java
deleted file mode 100644
index 5befff7..0000000
--- a/src/test/kotlin/function/builtin/GENSYMTest.java
+++ /dev/null
@@ -1,42 +0,0 @@
-package function.builtin;
-
-import function.ArgumentValidator.TooManyArgumentsException;
-import org.junit.Test;
-import testutil.SymbolAndFunctionCleaner;
-import token.TokenFactory.BadCharacterException;
-
-import static function.builtin.GENSYM.GENSYM_PREFIX;
-import static testutil.TestUtilities.assertSExpressionsDoNotMatch;
-import static testutil.TestUtilities.assertSExpressionsMatch;
-import static testutil.TestUtilities.evaluateString;
-import static testutil.TypeAssertions.assertSymbol;
-
-public class GENSYMTest extends SymbolAndFunctionCleaner {
-
-    @Test
-    public void gensymCreatesSymbol() {
-        assertSymbol(evaluateString("(gensym)"));
-    }
-
-    @Test
-    public void gensymCreatesUniqueSymbol() {
-        assertSExpressionsDoNotMatch(evaluateString("(gensym)"), evaluateString("(gensym)"));
-    }
-
-    @Test
-    public void simpleGensymUsage() {
-        String input = "(let ((x (gensym))) (set x 23) (eval x))";
-        assertSExpressionsMatch(evaluateString("23"), evaluateString(input));
-    }
-
-    @Test(expected = BadCharacterException.class)
-    public void cannotUseGensymValueManually() {
-        String variableName = GENSYM_PREFIX + 1;
-        evaluateString("(setq " + variableName + " 100)");
-    }
-
-    @Test(expected = TooManyArgumentsException.class)
-    public void gensymWithTooManyArguments() {
-        evaluateString("(gensym 1)");
-    }
-}
diff --git a/src/test/kotlin/function/builtin/GensymTest.kt b/src/test/kotlin/function/builtin/GensymTest.kt
new file mode 100644
index 0000000..63baa3e
--- /dev/null
+++ b/src/test/kotlin/function/builtin/GensymTest.kt
@@ -0,0 +1,47 @@
+package function.builtin
+
+import function.ArgumentValidator.TooManyArgumentsException
+import function.builtin.Gensym.Companion.GENSYM_PREFIX
+import org.junit.jupiter.api.Assertions.assertThrows
+import org.junit.jupiter.api.Test
+import testutil.SymbolAndFunctionCleaner
+import testutil.TestUtilities.assertSExpressionsDoNotMatch
+import testutil.TestUtilities.assertSExpressionsMatch
+import testutil.TestUtilities.evaluateString
+import testutil.TypeAssertions.assertSymbol
+import token.TokenFactory.BadCharacterException
+
+class GensymTest : SymbolAndFunctionCleaner() {
+
+    @Test
+    fun gensymCreatesSymbol() {
+        assertSymbol(evaluateString("(gensym)"))
+    }
+
+    @Test
+    fun gensymCreatesUniqueSymbol() {
+        assertSExpressionsDoNotMatch(evaluateString("(gensym)"), evaluateString("(gensym)"))
+    }
+
+    @Test
+    fun simpleGensymUsage() {
+        val input = "(let ((x (gensym))) (set x 23) (eval x))"
+        assertSExpressionsMatch(evaluateString("23"), evaluateString(input))
+    }
+
+    @Test
+    fun cannotUseGensymValueManually() {
+        val variableName = GENSYM_PREFIX + 1
+
+        assertThrows(BadCharacterException::class.java) {
+            evaluateString("(setq $variableName 100)")
+        }
+    }
+
+    @Test
+    fun gensymWithTooManyArguments() {
+        assertThrows(TooManyArgumentsException::class.java) {
+            evaluateString("(gensym 1)")
+        }
+    }
+}
diff --git a/src/test/kotlin/function/builtin/SYMBOLSTest.java b/src/test/kotlin/function/builtin/SYMBOLSTest.java
deleted file mode 100644
index 1c47a78..0000000
--- a/src/test/kotlin/function/builtin/SYMBOLSTest.java
+++ /dev/null
@@ -1,56 +0,0 @@
-package function.builtin;
-
-import function.ArgumentValidator.TooManyArgumentsException;
-import org.junit.Test;
-import testutil.SymbolAndFunctionCleaner;
-
-import static testutil.TestUtilities.assertSExpressionsMatch;
-import static testutil.TestUtilities.evaluateString;
-
-public class SYMBOLSTest extends SymbolAndFunctionCleaner {
-
-    @Test
-    public void noSymbols() {
-        assertSExpressionsMatch(evaluateString("'(nil)"), evaluateString("(symbols)"));
-    }
-
-    @Test
-    public void globalSymbol() {
-        evaluateString("(setq x 10)");
-        assertSExpressionsMatch(evaluateString("'(((x 10)))"), evaluateString("(symbols)"));
-    }
-
-    @Test
-    public void multipleSymbolsSorted() {
-        evaluateString("(setq x 10)");
-        evaluateString("(setq a 20)");
-        evaluateString("(setq y 30)");
-        evaluateString("(setq w 40)");
-        evaluateString("(setq e 50)");
-
-        assertSExpressionsMatch(evaluateString("'(((a 20) (e 50) (w 40) (x 10) (y 30)))"), evaluateString("(symbols)"));
-    }
-
-    @Test
-    public void fullExecutionContext() {
-        evaluateString("(setq x 10)");
-        evaluateString("(setq y 30)");
-
-        assertSExpressionsMatch(evaluateString("'(((x 10) (y 30)) ((a 100) (q 99) (z nil)))"),
-                                evaluateString("(let ((q 99) (a 100) (z)) (symbols))"));
-    }
-
-    @Test
-    public void updateSymbolInLet() {
-        evaluateString("(setq x 10)");
-        evaluateString("(setq y 30)");
-
-        assertSExpressionsMatch(evaluateString("'(((x 10) (y 30)) ((q 99) (x 1) (z 2)))"),
-                                evaluateString("(let ((q 99) (x 100) (z 2)) (setq x 1) (symbols))"));
-    }
-
-    @Test(expected = TooManyArgumentsException.class)
-    public void symbolsWithTooManyArguments() {
-        evaluateString("(symbols 1)");
-    }
-}
diff --git a/src/test/kotlin/function/builtin/SYMBOL_FUNCTIONTest.java b/src/test/kotlin/function/builtin/SYMBOL_FUNCTIONTest.java
deleted file mode 100644
index e27ff9a..0000000
--- a/src/test/kotlin/function/builtin/SYMBOL_FUNCTIONTest.java
+++ /dev/null
@@ -1,72 +0,0 @@
-package function.builtin;
-
-import function.ArgumentValidator.BadArgumentTypeException;
-import function.ArgumentValidator.TooFewArgumentsException;
-import function.ArgumentValidator.TooManyArgumentsException;
-import function.builtin.SYMBOL_FUNCTION.UndefinedSymbolFunctionException;
-import org.junit.Test;
-import sexpression.Nil;
-import testutil.SymbolAndFunctionCleaner;
-
-import static error.Severity.ERROR;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertTrue;
-import static testutil.TestUtilities.evaluateString;
-
-public class SYMBOL_FUNCTIONTest extends SymbolAndFunctionCleaner {
-
-    @Test
-    public void symbolFunction_BuiltInFunction() {
-        String input = "(symbol-function '+)";
-
-        assertEquals("#<FUNCTION +>", evaluateString(input).toString());
-    }
-
-    @Test
-    public void symbolFunction_BuiltInSpecialFunction() {
-        String input = "(symbol-function 'if)";
-
-        assertEquals("#<SPECIAL-FUNCTION IF>", evaluateString(input).toString());
-    }
-
-    @Test
-    public void symbolFunction_UserDefinedFunction() {
-        String defineUserFunction = "(defun y (n m) (+ n m))";
-        String input = "(symbol-function 'y)";
-
-        evaluateString(defineUserFunction);
-        assertEquals("(Y (N M) (+ N M))", evaluateString(input).toString());
-    }
-
-    @Test(expected = UndefinedSymbolFunctionException.class)
-    public void symbolFunction_NonFunction() {
-        String input = "(symbol-function 'a)";
-
-        evaluateString(input);
-    }
-
-    @Test(expected = BadArgumentTypeException.class)
-    public void symbolFunctionWithBadArgumentType() {
-        evaluateString("(symbol-function 2)");
-    }
-
-    @Test(expected = TooManyArgumentsException.class)
-    public void symbolFunctionWithTooManyArguments() {
-        evaluateString("(symbol-function 'a 'b)");
-    }
-
-    @Test(expected = TooFewArgumentsException.class)
-    public void symbolFunctionWithTooFewArguments() {
-        evaluateString("(symbol-function)");
-    }
-
-    @Test
-    public void undefinedSymbolFunctionException_HasCorrectAttributes() {
-        UndefinedSymbolFunctionException e = new UndefinedSymbolFunctionException(Nil.INSTANCE);
-
-        assertEquals(ERROR, e.getSeverity());
-        assertNotNull(e.getMessage());
-        assertTrue(e.getMessage().length() > 0);
-    }
-}
diff --git a/src/test/kotlin/function/builtin/SymbolFunctionTest.kt b/src/test/kotlin/function/builtin/SymbolFunctionTest.kt
new file mode 100644
index 0000000..0ab6429
--- /dev/null
+++ b/src/test/kotlin/function/builtin/SymbolFunctionTest.kt
@@ -0,0 +1,76 @@
+package function.builtin
+
+import function.ArgumentValidator.BadArgumentTypeException
+import function.ArgumentValidator.TooFewArgumentsException
+import function.ArgumentValidator.TooManyArgumentsException
+import function.builtin.SymbolFunction.UndefinedSymbolFunctionException
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Assertions.assertThrows
+import org.junit.jupiter.api.Test
+import sexpression.Nil
+import testutil.LispTestInstance
+import testutil.SymbolAndFunctionCleaner
+import testutil.TestUtilities.assertIsErrorWithMessage
+import testutil.TestUtilities.evaluateString
+
+@LispTestInstance
+class SymbolFunctionTest : SymbolAndFunctionCleaner() {
+
+    @Test
+    fun symbolFunction_BuiltInFunction() {
+        val input = "(symbol-function '+)"
+
+        assertThat(evaluateString(input).toString()).isEqualTo("#<FUNCTION +>")
+    }
+
+    @Test
+    fun symbolFunction_BuiltInSpecialFunction() {
+        val input = "(symbol-function 'if)"
+
+        assertThat(evaluateString(input).toString()).isEqualTo("#<SPECIAL-FUNCTION IF>")
+    }
+
+    @Test
+    fun symbolFunction_UserDefinedFunction() {
+        val defineUserFunction = "(defun y (n m) (+ n m))"
+        val input = "(symbol-function 'y)"
+
+        evaluateString(defineUserFunction)
+        assertThat(evaluateString(input).toString()).isEqualTo("(Y (N M) (+ N M))")
+    }
+
+    @Test
+    fun symbolFunction_NonFunction() {
+        val input = "(symbol-function 'a)"
+
+        assertThrows(UndefinedSymbolFunctionException::class.java) {
+            evaluateString(input)
+        }
+    }
+
+    @Test
+    fun symbolFunctionWithBadArgumentType() {
+        assertThrows(BadArgumentTypeException::class.java) {
+            evaluateString("(symbol-function 2)")
+        }
+    }
+
+    @Test
+    fun symbolFunctionWithTooManyArguments() {
+        assertThrows(TooManyArgumentsException::class.java) {
+            evaluateString("(symbol-function 'a 'b)")
+        }
+    }
+
+    @Test
+    fun symbolFunctionWithTooFewArguments() {
+        assertThrows(TooFewArgumentsException::class.java) {
+            evaluateString("(symbol-function)")
+        }
+    }
+
+    @Test
+    fun undefinedSymbolFunctionException_HasCorrectAttributes() {
+        assertIsErrorWithMessage(UndefinedSymbolFunctionException(Nil))
+    }
+}
diff --git a/src/test/kotlin/function/builtin/SymbolsTest.kt b/src/test/kotlin/function/builtin/SymbolsTest.kt
new file mode 100644
index 0000000..c946a57
--- /dev/null
+++ b/src/test/kotlin/function/builtin/SymbolsTest.kt
@@ -0,0 +1,60 @@
+package function.builtin
+
+import function.ArgumentValidator.TooManyArgumentsException
+import org.junit.jupiter.api.Assertions.assertThrows
+import org.junit.jupiter.api.Test
+import testutil.LispTestInstance
+import testutil.SymbolAndFunctionCleaner
+import testutil.TestUtilities.assertSExpressionsMatch
+import testutil.TestUtilities.evaluateString
+
+@LispTestInstance
+class SymbolsTest : SymbolAndFunctionCleaner() {
+
+    @Test
+    fun noSymbols() {
+        assertSExpressionsMatch(evaluateString("'(nil)"), evaluateString("(symbols)"))
+    }
+
+    @Test
+    fun globalSymbol() {
+        evaluateString("(setq x 10)")
+        assertSExpressionsMatch(evaluateString("'(((x 10)))"), evaluateString("(symbols)"))
+    }
+
+    @Test
+    fun multipleSymbolsSorted() {
+        evaluateString("(setq x 10)")
+        evaluateString("(setq a 20)")
+        evaluateString("(setq y 30)")
+        evaluateString("(setq w 40)")
+        evaluateString("(setq e 50)")
+
+        assertSExpressionsMatch(evaluateString("'(((a 20) (e 50) (w 40) (x 10) (y 30)))"), evaluateString("(symbols)"))
+    }
+
+    @Test
+    fun fullExecutionContext() {
+        evaluateString("(setq x 10)")
+        evaluateString("(setq y 30)")
+
+        assertSExpressionsMatch(evaluateString("'(((x 10) (y 30)) ((a 100) (q 99) (z nil)))"),
+                                evaluateString("(let ((q 99) (a 100) (z)) (symbols))"))
+    }
+
+    @Test
+    fun updateSymbolInLet() {
+        evaluateString("(setq x 10)")
+        evaluateString("(setq y 30)")
+
+        assertSExpressionsMatch(evaluateString("'(((x 10) (y 30)) ((q 99) (x 1) (z 2)))"),
+                                evaluateString("(let ((q 99) (x 100) (z 2)) (setq x 1) (symbols))"))
+    }
+
+    @Test
+    fun symbolsWithTooManyArguments() {
+        assertThrows(TooManyArgumentsException::class.java) {
+            evaluateString("(symbols 1)")
+        }
+    }
+}
diff --git a/src/test/kotlin/function/builtin/predicate/GENSYM_EQUALTest.java b/src/test/kotlin/function/builtin/predicate/GENSYM_EQUALTest.java
deleted file mode 100644
index 154d201..0000000
--- a/src/test/kotlin/function/builtin/predicate/GENSYM_EQUALTest.java
+++ /dev/null
@@ -1,160 +0,0 @@
-package function.builtin.predicate;
-
-import function.ArgumentValidator.TooFewArgumentsException;
-import function.ArgumentValidator.TooManyArgumentsException;
-import org.junit.Test;
-import testutil.SymbolAndFunctionCleaner;
-
-import static testutil.TestUtilities.evaluateString;
-import static testutil.TypeAssertions.assertNil;
-import static testutil.TypeAssertions.assertT;
-
-public class GENSYM_EQUALTest extends SymbolAndFunctionCleaner {
-
-    @Test
-    public void gensymEqualWithTwoEqualAtoms() {
-        String input = "(gensym-equal 'a 'a)";
-
-        assertT(evaluateString(input));
-    }
-
-    @Test
-    public void gensymEqualWithTwoEqualAtomsAndAlias() {
-        String input = "(gensym-equal? 'a 'a)";
-
-        assertT(evaluateString(input));
-    }
-
-    @Test
-    public void gensymEqualWithTwoUnequalAtoms() {
-        String input = "(gensym-equal 'a 'b)";
-
-        assertNil(evaluateString(input));
-    }
-
-    @Test
-    public void gensymEqualWithTwoEqualNumbers() {
-        String input = "(gensym-equal -4 -4)";
-
-        assertT(evaluateString(input));
-    }
-
-    @Test
-    public void gensymEqualWithTwoUnequalNumbers() {
-        String input = "(gensym-equal +5 +7)";
-
-        assertNil(evaluateString(input));
-    }
-
-    @Test
-    public void gensymEqualWithTwoEqualStrings() {
-        String input = "(gensym-equal \"potato\" \"potato\")";
-
-        assertT(evaluateString(input));
-    }
-
-    @Test
-    public void gensymEqualWithTwoUnequalStrings() {
-        String input = "(gensym-equal \"tomato\" \"potato\")";
-
-        assertNil(evaluateString(input));
-    }
-
-    @Test
-    public void gensymEqualWithTwoDifferentCasedStrings() {
-        String input = "(gensym-equal \"Potato\" \"potato\")";
-
-        assertNil(evaluateString(input));
-    }
-
-    @Test
-    public void gensymEqualWithAtomAndList() {
-        String input = "(gensym-equal \"string\" '(m i k e))";
-
-        assertNil(evaluateString(input));
-    }
-
-    @Test
-    public void gensymEqualWithListAndAtom() {
-        String input = "(gensym-equal '(m i k e) \"string\")";
-
-        assertNil(evaluateString(input));
-    }
-
-    @Test
-    public void gensymEqualWithTwoEqualLists() {
-        String input = "(gensym-equal '(1 2 3) '(1 2 3))";
-
-        assertT(evaluateString(input));
-    }
-
-    @Test
-    public void gensymEqualWithTwoUnequalLists() {
-        String input = "(gensym-equal '(1 2 3) '(1 3 3))";
-
-        assertNil(evaluateString(input));
-    }
-
-    @Test
-    public void gensymEqualWithTwoEqualNestedLists() {
-        String input = "(gensym-equal '(1 ((2) 3)) '(1 ((2) 3)))";
-
-        assertT(evaluateString(input));
-    }
-
-    @Test(expected = TooManyArgumentsException.class)
-    public void gensymEqualWithTooManyArguments() {
-        evaluateString("(gensym-equal 1 2 3)");
-    }
-
-    @Test(expected = TooFewArgumentsException.class)
-    public void gensymEqualWithTooFewArguments() {
-        evaluateString("(gensym-equal 1)");
-    }
-
-    @Test
-    public void gensymEqualWithGensyms() {
-        String input = "(gensym-equal (gensym) (gensym))";
-
-        assertT(evaluateString(input));
-    }
-
-    @Test
-    public void gensymEqualWithNestedGensyms() {
-        String input = "(gensym-equal `(1 ,(gensym) (2 ,(gensym))) `(1 ,(gensym) (2 ,(gensym))))";
-
-        assertT(evaluateString(input));
-    }
-
-    @Test
-    public void gensymEqualWithUnmatchedGensymPositions() {
-        String input = "(gensym-equal (let ((one (gensym))) `(,one ,one))"
-                       + " (let ((one (gensym)) (two (gensym))) `(,one ,two)))";
-
-        assertNil(evaluateString(input));
-    }
-
-    @Test
-    public void gensymEqualWithMatchedGensymPositions() {
-        String input = "(gensym-equal (let ((one (gensym))) `(,one ,one))"
-                       + " (let ((one (gensym)) (two (gensym))) `(,one ,one)))";
-
-        assertT(evaluateString(input));
-    }
-
-    @Test
-    public void gensymEqualWithComplexMatchedGensymPositions() {
-        String input = "(gensym-equal (let ((x (gensym)) (y (gensym)) (z (gensym))) `(,x (,y ,z)))"
-                       + " (let ((a (gensym)) (b (gensym)) (c (gensym))) `(,c (,a ,b))))";
-
-        assertT(evaluateString(input));
-    }
-
-    @Test
-    public void gensymEqualWithComplexUnmatchedGensymPositions() {
-        String input = "(gensym-equal (let ((x (gensym)) (y (gensym)) (z (gensym))) `(,x , y (,z ,z)))"
-                       + " (let ((a (gensym)) (b (gensym)) (c (gensym))) `(,a ,c (,b ,c))))";
-
-        assertNil(evaluateString(input));
-    }
-}
diff --git a/src/test/kotlin/function/builtin/predicate/GensymEqualTest.kt b/src/test/kotlin/function/builtin/predicate/GensymEqualTest.kt
new file mode 100644
index 0000000..2b00f06
--- /dev/null
+++ b/src/test/kotlin/function/builtin/predicate/GensymEqualTest.kt
@@ -0,0 +1,166 @@
+package function.builtin.predicate
+
+import function.ArgumentValidator.TooFewArgumentsException
+import function.ArgumentValidator.TooManyArgumentsException
+import org.junit.jupiter.api.Assertions.assertThrows
+import org.junit.jupiter.api.Test
+import testutil.LispTestInstance
+import testutil.SymbolAndFunctionCleaner
+import testutil.TestUtilities.evaluateString
+import testutil.TypeAssertions.assertNil
+import testutil.TypeAssertions.assertT
+
+@LispTestInstance
+class GensymEqualTest : SymbolAndFunctionCleaner() {
+
+    @Test
+    fun gensymEqualWithTwoEqualAtoms() {
+        val input = "(gensym-equal 'a 'a)"
+
+        assertT(evaluateString(input))
+    }
+
+    @Test
+    fun gensymEqualWithTwoEqualAtomsAndAlias() {
+        val input = "(gensym-equal? 'a 'a)"
+
+        assertT(evaluateString(input))
+    }
+
+    @Test
+    fun gensymEqualWithTwoUnequalAtoms() {
+        val input = "(gensym-equal 'a 'b)"
+
+        assertNil(evaluateString(input))
+    }
+
+    @Test
+    fun gensymEqualWithTwoEqualNumbers() {
+        val input = "(gensym-equal -4 -4)"
+
+        assertT(evaluateString(input))
+    }
+
+    @Test
+    fun gensymEqualWithTwoUnequalNumbers() {
+        val input = "(gensym-equal +5 +7)"
+
+        assertNil(evaluateString(input))
+    }
+
+    @Test
+    fun gensymEqualWithTwoEqualStrings() {
+        val input = "(gensym-equal \"potato\" \"potato\")"
+
+        assertT(evaluateString(input))
+    }
+
+    @Test
+    fun gensymEqualWithTwoUnequalStrings() {
+        val input = "(gensym-equal \"tomato\" \"potato\")"
+
+        assertNil(evaluateString(input))
+    }
+
+    @Test
+    fun gensymEqualWithTwoDifferentCasedStrings() {
+        val input = "(gensym-equal \"Potato\" \"potato\")"
+
+        assertNil(evaluateString(input))
+    }
+
+    @Test
+    fun gensymEqualWithAtomAndList() {
+        val input = "(gensym-equal \"string\" '(m i k e))"
+
+        assertNil(evaluateString(input))
+    }
+
+    @Test
+    fun gensymEqualWithListAndAtom() {
+        val input = "(gensym-equal '(m i k e) \"string\")"
+
+        assertNil(evaluateString(input))
+    }
+
+    @Test
+    fun gensymEqualWithTwoEqualLists() {
+        val input = "(gensym-equal '(1 2 3) '(1 2 3))"
+
+        assertT(evaluateString(input))
+    }
+
+    @Test
+    fun gensymEqualWithTwoUnequalLists() {
+        val input = "(gensym-equal '(1 2 3) '(1 3 3))"
+
+        assertNil(evaluateString(input))
+    }
+
+    @Test
+    fun gensymEqualWithTwoEqualNestedLists() {
+        val input = "(gensym-equal '(1 ((2) 3)) '(1 ((2) 3)))"
+
+        assertT(evaluateString(input))
+    }
+
+    @Test
+    fun gensymEqualWithTooManyArguments() {
+        assertThrows(TooManyArgumentsException::class.java) {
+            evaluateString("(gensym-equal 1 2 3)")
+        }
+    }
+
+    @Test
+    fun gensymEqualWithTooFewArguments() {
+        assertThrows(TooFewArgumentsException::class.java) {
+            evaluateString("(gensym-equal 1)")
+        }
+    }
+
+    @Test
+    fun gensymEqualWithGensyms() {
+        val input = "(gensym-equal (gensym) (gensym))"
+
+        assertT(evaluateString(input))
+    }
+
+    @Test
+    fun gensymEqualWithNestedGensyms() {
+        val input = "(gensym-equal `(1 ,(gensym) (2 ,(gensym))) `(1 ,(gensym) (2 ,(gensym))))"
+
+        assertT(evaluateString(input))
+    }
+
+    @Test
+    fun gensymEqualWithUnmatchedGensymPositions() {
+        val input = "(gensym-equal (let ((one (gensym))) `(,one ,one))" +
+                " (let ((one (gensym)) (two (gensym))) `(,one ,two)))"
+
+        assertNil(evaluateString(input))
+    }
+
+    @Test
+    fun gensymEqualWithMatchedGensymPositions() {
+        val input = "(gensym-equal (let ((one (gensym))) `(,one ,one))" +
+                " (let ((one (gensym)) (two (gensym))) `(,one ,one)))"
+
+        assertT(evaluateString(input))
+    }
+
+    @Test
+    fun gensymEqualWithComplexMatchedGensymPositions() {
+        val input = "(gensym-equal (let ((x (gensym)) (y (gensym)) (z (gensym))) `(,x (,y ,z)))" +
+                " (let ((a (gensym)) (b (gensym)) (c (gensym))) `(,c (,a ,b))))"
+
+        assertT(evaluateString(input))
+    }
+
+    @Test
+    fun gensymEqualWithComplexUnmatchedGensymPositions() {
+        val input = "(gensym-equal (let ((x (gensym)) (y (gensym)) (z (gensym))) `(,x , y (,z ,z)))" +
+                " (let ((a (gensym)) (b (gensym)) (c (gensym))) `(,a ,c (,b ,c))))"
+
+        assertNil(evaluateString(input))
+    }
+}