diff --git a/tests/test_lex.py b/tests/test_lex.py
new file mode 100644
index 0000000..d1aa218
--- /dev/null
+++ b/tests/test_lex.py
@@ -0,0 +1,93 @@
+import pytest
+from sly import Lexer
+
+class CalcLexer(Lexer):
+    # Set of token names.   This is always required
+    tokens = {
+        'ID',
+        'NUMBER',
+        'PLUS',
+        'MINUS',
+        'TIMES',
+        'DIVIDE',
+        'ASSIGN',
+        'LT',
+        'LE',
+        }
+
+    literals = { '(', ')' }
+
+    # String containing ignored characters between tokens
+    ignore = ' \t'
+
+    # Regular expression rules for tokens
+    ID      = r'[a-zA-Z_][a-zA-Z0-9_]*'
+    PLUS    = r'\+'
+    MINUS   = r'-'
+    TIMES   = r'\*'
+    DIVIDE  = r'/'
+    ASSIGN  = r'='
+    LE      = r'<='
+    LT      = r'<'
+
+    @_(r'\d+')
+    def NUMBER(self, t):
+        t.value = int(t.value)
+        return t
+
+    # Ignored text
+    ignore_comment = r'\#.*'
+
+    @_(r'\n+')
+    def newline(self, t):
+        self.lineno += t.value.count('\n')
+
+    # Attached rule
+    def ID(self, t):
+        t.value = t.value.upper()
+        return t
+
+    def error(self, value):
+        self.errors.append(value)
+        self.index += 1
+
+    def __init__(self):
+        self.errors = []
+
+# Test basic recognition of various tokens and literals
+def test_tokens():
+    lexer = CalcLexer()
+    toks = list(lexer.tokenize('abc 123 + - * / = < <= ( )'))
+    types = [t.type for t in toks]
+    vals = [t.value for t in toks]
+    assert types == ['ID','NUMBER','PLUS','MINUS','TIMES','DIVIDE','ASSIGN','LT','LE','(',')']
+    assert vals == ['ABC', 123, '+', '-', '*', '/', '=', '<', '<=', '(', ')']
+
+# Test ignored comments and newlines
+def test_ignored():
+    lexer = CalcLexer()
+    toks = list(lexer.tokenize('\n\n# A comment\n123\nabc\n'))
+    types = [t.type for t in toks]
+    vals = [t.value for t in toks]
+    linenos = [t.lineno for t in toks]
+    assert types == ['NUMBER', 'ID']
+    assert vals == [123, 'ABC']
+    assert linenos == [4,5]
+    assert lexer.lineno == 6
+
+# Test error handling
+def test_error():
+    lexer = CalcLexer()
+    toks = list(lexer.tokenize('123 :+-'))
+    types = [t.type for t in toks]
+    vals = [t.value for t in toks]
+    assert types == ['NUMBER', 'PLUS', 'MINUS']
+    assert vals == [123, '+', '-']
+    assert lexer.errors == [ ':+-' ]
+
+    
+    
+    
+
+
+
diff --git a/tests/test_parser.py b/tests/test_parser.py
new file mode 100644
index 0000000..38db4fe
--- /dev/null
+++ b/tests/test_parser.py
@@ -0,0 +1,141 @@
+import pytest
+from sly import Lexer, Parser
+
+class CalcLexer(Lexer):
+    # Set of token names.   This is always required
+    tokens = {
+        'ID',
+        'NUMBER',
+        'PLUS',
+        'MINUS',
+        'TIMES',
+        'DIVIDE',
+        'ASSIGN',
+        }
+
+    literals = { '(', ')' }
+
+    # String containing ignored characters between tokens
+    ignore = ' \t'
+
+    # Regular expression rules for tokens
+    ID      = r'[a-zA-Z_][a-zA-Z0-9_]*'
+    PLUS    = r'\+'
+    MINUS   = r'-'
+    TIMES   = r'\*'
+    DIVIDE  = r'/'
+    ASSIGN  = r'='
+
+    @_(r'\d+')
+    def NUMBER(self, t):
+        t.value = int(t.value)
+        return t
+
+    # Ignored text
+    ignore_comment = r'\#.*'
+
+    @_(r'\n+')
+    def newline(self, t):
+        self.lineno += t.value.count('\n')
+
+    def error(self, value):
+        self.errors.append(value)
+        self.index += 1
+
+    def __init__(self):
+        self.errors = []
+
+class CalcParser(Parser):
+    tokens = CalcLexer.tokens
+
+    precedence = (
+        ('left', 'PLUS', 'MINUS'),
+        ('left', 'TIMES', 'DIVIDE'),
+        ('right', 'UMINUS'),
+        )
+
+    def __init__(self):
+        self.names = { }
+        self.errors = [ ]
+
+    @_('ID ASSIGN expr')
+    def statement(self, p):
+        self.names[p.ID] = p.expr
+
+    @_('expr')
+    def statement(self, p):
+        return p.expr
+
+    @_('expr PLUS expr')
+    def expr(self, p):
+        return p.expr0 + p.expr1
+
+    @_('expr MINUS expr')
+    def expr(self, p):
+        return p.expr0 - p.expr1
+
+    @_('expr TIMES expr')
+    def expr(self, p):
+        return p.expr0 * p.expr1
+
+    @_('expr DIVIDE expr')
+    def expr(self, p):
+        return p.expr0 / p.expr1
+
+    @_('MINUS expr %prec UMINUS')
+    def expr(self, p):
+        return -p.expr
+
+    @_('"(" expr ")"')
+    def expr(self, p):
+        return p.expr
+
+    @_('NUMBER')
+    def expr(self, p):
+        return p.NUMBER
+
+    @_('ID')
+    def expr(self, p):
+        try:
+            return self.names[p.ID]
+        except LookupError:
+            self.errors.append(('undefined', p.ID))
+            return 0
+
+    def error(self, tok):
+        self.errors.append(tok)
+
+
+# Test basic recognition of various tokens and literals
+def test_simple():
+    lexer = CalcLexer()
+    parser = CalcParser()
+
+    result = parser.parse(lexer.tokenize('a = 3 + 4 * (5 + 6)'))
+    assert result == None
+    assert parser.names['a'] == 47
+
+    result = parser.parse(lexer.tokenize('3 + 4 * (5 + 6)'))
+    assert result == 47
+
+def test_parse_error():
+    lexer = CalcLexer()
+    parser = CalcParser()
+
+    result = parser.parse(lexer.tokenize('a 123 4 + 5'))
+    assert result == 9
+    assert len(parser.errors) == 1
+    assert parser.errors[0].type == 'NUMBER'
+    assert parser.errors[0].value == 123
+
+# TO DO:  Add tests
+# - error productions
+# - embedded actions
+# - lineno tracking
+# - various error cases caught during parser construction
+
+    
+    
+
+
+