[GR-10323] Constant Math.tau is missing.

Author: ppisl

graalpython/com.oracle.graal.python.test/src/tests/test_math.py

@@ -102,6 +102,12 @@ def ftest(self, name, got, expected, ulp_tol=5, abs_tol=0.0):
         if failure is not None:
             self.fail("{}: {}".format(name, failure))
 
+    def testConstants(self):
+        # Ref: Abramowitz & Stegun (Dover, 1965)
+        self.ftest('pi', math.pi, 3.141592653589793238462643)
+        self.ftest('e', math.e, 2.718281828459045235360287)
+        self.assertEqual(math.tau, 2*math.pi)
+
     def test_ceil_basic(self):
         self.assertEqual(math.ceil(10), 10)
         self.assertEqual(math.ceil(-10), -10)

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/MathModuleBuiltins.java

@@ -68,6 +68,7 @@ public MathModuleBuiltins() {
         // Add constant values
         builtinConstants.put("pi", Math.PI);
         builtinConstants.put("e", Math.E);
+        builtinConstants.put("tau", 2*Math.PI);
     }
 
     // math.sqrt