1 files changed, 88 insertions, 0 deletions
diff --git a/python/mozbuild/mozbuild/test/test_expression.py b/python/mozbuild/mozbuild/test/test_expression.py
new file mode 100644
index 0000000000..535e62bf43
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/test_expression.py
@@ -0,0 +1,88 @@
+import unittest
+
+import mozunit
+
+from mozbuild.preprocessor import Context, Expression
+
+
+class TestContext(unittest.TestCase):
+    """
+    Unit tests for the Context class
+    """
+
+    def setUp(self):
+        self.c = Context()
+        self.c["FAIL"] = "PASS"
+
+    def test_string_literal(self):
+        """test string literal, fall-through for undefined var in a Context"""
+        self.assertEqual(self.c["PASS"], "PASS")
+
+    def test_variable(self):
+        """test value for defined var in the Context class"""
+        self.assertEqual(self.c["FAIL"], "PASS")
+
+    def test_in(self):
+        """test 'var in context' to not fall for fallback"""
+        self.assertTrue("FAIL" in self.c)
+        self.assertTrue("PASS" not in self.c)
+
+
+class TestExpression(unittest.TestCase):
+    """
+    Unit tests for the Expression class
+    evaluate() is called with a context {FAIL: 'PASS'}
+    """
+
+    def setUp(self):
+        self.c = Context()
+        self.c["FAIL"] = "PASS"
+
+    def test_string_literal(self):
+        """Test for a string literal in an Expression"""
+        self.assertEqual(Expression("PASS").evaluate(self.c), "PASS")
+
+    def test_variable(self):
+        """Test for variable value in an Expression"""
+        self.assertEqual(Expression("FAIL").evaluate(self.c), "PASS")
+
+    def test_not(self):
+        """Test for the ! operator"""
+        self.assertTrue(Expression("!0").evaluate(self.c))
+        self.assertTrue(not Expression("!1").evaluate(self.c))
+
+    def test_equals(self):
+        """Test for the == operator"""
+        self.assertTrue(Expression("FAIL == PASS").evaluate(self.c))
+
+    def test_notequals(self):
+        """Test for the != operator"""
+        self.assertTrue(Expression("FAIL != 1").evaluate(self.c))
+
+    def test_logical_and(self):
+        """Test for the && operator"""
+        self.assertTrue(Expression("PASS == PASS && PASS != NOTPASS").evaluate(self.c))
+
+    def test_logical_or(self):
+        """Test for the || operator"""
+        self.assertTrue(
+            Expression("PASS == NOTPASS || PASS != NOTPASS").evaluate(self.c)
+        )
+
+    def test_logical_ops(self):
+        """Test for the && and || operators precedence"""
+        # Would evaluate to false if precedence was wrong
+        self.assertTrue(
+            Expression("PASS == PASS || PASS != NOTPASS && PASS == NOTPASS").evaluate(
+                self.c
+            )
+        )
+
+    def test_defined(self):
+        """Test for the defined() value"""
+        self.assertTrue(Expression("defined(FAIL)").evaluate(self.c))
+        self.assertTrue(Expression("!defined(PASS)").evaluate(self.c))
+
+
+if __name__ == "__main__":
+    mozunit.main()