diff --git a/src/table/FunctionTable.java b/src/table/FunctionTable.java
index 6366e4f..d00388a 100644
--- a/src/table/FunctionTable.java
+++ b/src/table/FunctionTable.java
@@ -25,15 +25,19 @@ public class FunctionTable {
         uniqueInstance.functionTable.put(functionName, function);
     }
     
+    public static void reset() {
+        uniqueInstance.initializeFunctionTable();
+    }
+    
     private HashMap<String, LispFunction> functionTable;
 
     private FunctionTable() {
-        this.functionTable = new HashMap<>();
-        
         initializeFunctionTable();
     }
 
     private void initializeFunctionTable() {
+        functionTable = new HashMap<>();
+
         functionTable.put("*", new MULTIPLY());
         functionTable.put("+", new PLUS());
         functionTable.put("-", new MINUS());
diff --git a/test/function/builtin/FUNCALLTester.java b/test/function/builtin/FUNCALLTester.java
index f14bee7..7c2d676 100644
--- a/test/function/builtin/FUNCALLTester.java
+++ b/test/function/builtin/FUNCALLTester.java
@@ -2,12 +2,23 @@ package function.builtin;
 
 import static testutil.TestUtilities.*;
 
-import org.junit.Test;
+import org.junit.*;
 
 import function.ArgumentValidator.TooFewArgumentsException;
+import table.FunctionTable;
 
 public class FUNCALLTester {
 
+    @Before
+    public void setUp() {
+        FunctionTable.reset();
+    }
+
+    @After
+    public void tearDown() {
+        FunctionTable.reset();
+    }
+
     @Test
     public void testFuncallWithNumbers() {
         String input = "(funcall '+ 1 2 3)";
diff --git a/test/function/builtin/SYMBOL_FUNCTIONTester.java b/test/function/builtin/SYMBOL_FUNCTIONTester.java
index 593fbe0..1cf33f4 100644
--- a/test/function/builtin/SYMBOL_FUNCTIONTester.java
+++ b/test/function/builtin/SYMBOL_FUNCTIONTester.java
@@ -3,14 +3,25 @@ package function.builtin;
 import static org.junit.Assert.*;
 import static testutil.TestUtilities.evaluateString;
 
-import org.junit.Test;
+import org.junit.*;
 
 import function.ArgumentValidator.*;
 import function.builtin.SYMBOL_FUNCTION.UndefinedSymbolFunctionException;
 import sexpression.Nil;
+import table.FunctionTable;
 
 public class SYMBOL_FUNCTIONTester {
 
+    @Before
+    public void setUp() {
+        FunctionTable.reset();
+    }
+
+    @After
+    public void tearDown() {
+        FunctionTable.reset();
+    }
+
     @Test
     public void testSymbolFunction_BuiltinFunction() {
         String input = "(symbol-function '+)";
diff --git a/test/function/builtin/special/DEFUNTester.java b/test/function/builtin/special/DEFUNTester.java
index 4e2163a..d23f6a3 100644
--- a/test/function/builtin/special/DEFUNTester.java
+++ b/test/function/builtin/special/DEFUNTester.java
@@ -9,6 +9,7 @@ import org.junit.*;
 
 import environment.Environment;
 import function.ArgumentValidator.*;
+import table.FunctionTable;
 
 public class DEFUNTester {
 
@@ -22,6 +23,12 @@ public class DEFUNTester {
     public void setUp() {
         this.outputStream = new ByteArrayOutputStream();
         Environment.getInstance().setOutput(new PrintStream(outputStream));
+        FunctionTable.reset();
+    }
+
+    @After
+    public void tearDown() {
+        FunctionTable.reset();
     }
 
     @Test
diff --git a/test/table/ExecutionContextTester.java b/test/table/ExecutionContextTester.java
new file mode 100644
index 0000000..2da0d9e
--- /dev/null
+++ b/test/table/ExecutionContextTester.java
@@ -0,0 +1,84 @@
+package table;
+
+import static org.junit.Assert.*;
+
+import org.junit.*;
+
+import sexpression.*;
+
+public class ExecutionContextTester {
+
+    private ExecutionContext executionContext;
+
+    public ExecutionContextTester() {
+        this.executionContext = ExecutionContext.getInstance();
+    }
+
+    @Before
+    public void setUp() {
+        executionContext.clearContext();
+    }
+
+    @After
+    public void tearDown() {
+        executionContext.clearContext();
+    }
+
+    @Test
+    public void assignANewScope() {
+        SymbolTable scope = new SymbolTable();
+        executionContext.setScope(scope);
+
+        assertEquals(scope, executionContext.getScope());
+    }
+
+    @Test
+    public void clearContext() {
+        SymbolTable scope = new SymbolTable();
+        executionContext.setScope(scope);
+
+        assertEquals(scope, executionContext.getScope());
+        executionContext.clearContext();
+        assertNotEquals(scope, executionContext.getScope());
+        assertNull(executionContext.getScope().getParent());
+    }
+
+    @Test
+    public void lookupVariable() {
+        executionContext.getScope().put("test", Symbol.T);
+
+        assertEquals(Symbol.T, executionContext.lookupSymbolValue("test"));
+    }
+
+    @Test
+    public void lookupLocalVariable() {
+        SymbolTable scope = new SymbolTable(executionContext.getScope());
+
+        scope.put("local", Symbol.T);
+        executionContext.setScope(scope);
+
+        assertEquals(Symbol.T, executionContext.lookupSymbolValue("local"));
+    }
+
+    @Test
+    public void lookupGlobalVariable() {
+        SymbolTable scope = new SymbolTable(executionContext.getScope());
+
+        executionContext.getScope().put("global", Symbol.T);
+        executionContext.setScope(scope);
+
+        assertEquals(Symbol.T, executionContext.lookupSymbolValue("global"));
+    }
+
+    @Test
+    public void lookupShadowedVariable() {
+        SymbolTable scope = new SymbolTable(executionContext.getScope());
+
+        scope.put("shadowed", Nil.getInstance());
+        executionContext.getScope().put("shadowed", Symbol.T);
+        executionContext.setScope(scope);
+
+        assertEquals(Nil.getInstance(), executionContext.lookupSymbolValue("shadowed"));
+    }
+
+}
diff --git a/test/table/FunctionTableTester.java b/test/table/FunctionTableTester.java
new file mode 100644
index 0000000..6528834
--- /dev/null
+++ b/test/table/FunctionTableTester.java
@@ -0,0 +1,77 @@
+package table;
+
+import static org.junit.Assert.*;
+
+import org.junit.*;
+
+import function.LispFunction;
+import sexpression.*;
+
+public class FunctionTableTester {
+
+    private LispFunction createLispFunction() {
+        return new LispFunction() {
+
+            @Override
+            public SExpression call(Cons argList) {
+                return Symbol.T;
+            }
+        };
+    }
+
+    @Before
+    public void setUp() {
+        FunctionTable.reset();
+    }
+
+    @After
+    public void tearDown() {
+        FunctionTable.reset();
+    }
+
+    @Test
+    public void builtinFunctionIsDefined() {
+        assertTrue(FunctionTable.isAlreadyDefined("CONS"));
+    }
+
+    @Test
+    public void undefinedFunctionIsNotDefined() {
+        assertFalse(FunctionTable.isAlreadyDefined("undefined"));
+    }
+
+    @Test
+    public void lookupBuiltinFunction_ReturnsFunction() {
+        assertNotNull(FunctionTable.lookupFunction("CONS"));
+    }
+
+    @Test
+    public void lookupUndefinedFunction_ReturnsNull() {
+        assertNull(FunctionTable.lookupFunction("undefined"));
+    }
+
+    @Test
+    public void defineFunction() {
+        String functionName = "testFunction";
+        LispFunction testFunction = createLispFunction();
+
+        assertNull(FunctionTable.lookupFunction(functionName));
+        assertFalse(FunctionTable.isAlreadyDefined(functionName));
+
+        FunctionTable.defineFunction(functionName, testFunction);
+
+        assertTrue(FunctionTable.isAlreadyDefined(functionName));
+        assertEquals(testFunction, FunctionTable.lookupFunction(functionName));
+    }
+
+    @Test
+    public void resetFunctionTable() {
+        String functionName = "testFunction";
+        LispFunction testFunction = createLispFunction();
+        FunctionTable.defineFunction(functionName, testFunction);
+        FunctionTable.reset();
+
+        assertFalse(FunctionTable.isAlreadyDefined(functionName));
+        assertNull(FunctionTable.lookupFunction(functionName));
+    }
+
+}
diff --git a/test/table/SymbolTableTester.java b/test/table/SymbolTableTester.java
index 29a1e4d..85f98b4 100644
--- a/test/table/SymbolTableTester.java
+++ b/test/table/SymbolTableTester.java
@@ -11,7 +11,7 @@ public class SymbolTableTester {
     private SymbolTable symbolTable;
 
     @Before
-    public void setUp() throws Exception {
+    public void setUp() {
         symbolTable = new SymbolTable();
     }
 
@@ -23,12 +23,14 @@ public class SymbolTableTester {
     @Test
     public void lookupSymbolInTable() {
         symbolTable.put("symbol", Symbol.T);
+
         assertTrue(symbolTable.contains("symbol"));
     }
 
     @Test
     public void retrieveSymbolValue() {
         symbolTable.put("symbol", Symbol.T);
+
         assertEquals(Symbol.T, symbolTable.get("symbol"));
     }
 
@@ -36,6 +38,7 @@ public class SymbolTableTester {
     public void redefineSymbolValue() {
         symbolTable.put("symbol", Symbol.T);
         symbolTable.put("symbol", Nil.getInstance());
+
         assertEquals(Nil.getInstance(), symbolTable.get("symbol"));
     }