Add test for `core:math/big` permutation & combination procs

tests/core/math/big/test_core_math_big.odin

@@ -0,0 +1,37 @@
+package test_core_math_big
+
+import "core:math/big"
+import "core:testing"
+
+@(test)
+test_permutations_and_combinations :: proc(t: ^testing.T) {
+	{
+		calc, exp := &big.Int{}, &big.Int{}
+		defer big.destroy(calc, exp)
+		big.permutations_without_repetition(calc, 9000, 10)
+		big.int_atoi(exp, "3469387884476822917768284664849390080000")
+		equals, error := big.equals(calc, exp)
+		testing.expect(t, equals)
+		testing.expect_value(t, error, nil)
+	}
+
+	{
+		calc, exp := &big.Int{}, &big.Int{}
+		defer big.destroy(calc, exp)
+		big.combinations_with_repetition(calc, 9000, 10)
+		big.int_atoi(exp, "965678962435231708695393645683400")
+		equals, error := big.equals(calc, exp)
+		testing.expect(t, equals)
+		testing.expect_value(t, error, nil)
+	}
+
+	{
+		calc, exp := &big.Int{}, &big.Int{}
+		defer big.destroy(calc, exp)
+		big.combinations_without_repetition(calc, 9000, 10)
+		big.int_atoi(exp, "956070294443568925751842114431600")
+		equals, error := big.equals(calc, exp)
+		testing.expect(t, equals)
+		testing.expect_value(t, error, nil)
+	}
+}