From 666bb56670eb06a5324aefcf2fc8cc115a4db0d6 Mon Sep 17 00:00:00 2001
From: Eduard Bopp <eduard.bopp@aepsil0n.de>
Date: Thu, 23 Oct 2014 10:15:47 +0200
Subject: [PATCH] Assertion macros for approximate equality

For sake of readability and consistency with the standard library macros
assert! and assert_eq!, the macros assert_approx_eq! and assert_approx_eq_eps!
have been implemented based on the ApproxEq trait.

Upon failure these macros yield readable error messages including the input
values and the tolerance (epsilon) used to determine their approximate
equality.

Resolves #131.
---
 src/approx.rs   | 26 ++++++++++++++++++++++++++
 tests/approx.rs | 44 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+)
 create mode 100644 tests/approx.rs

diff --git a/src/approx.rs b/src/approx.rs
index 1604280..72deb3a 100644
--- a/src/approx.rs
+++ b/src/approx.rs
@@ -42,3 +42,29 @@ macro_rules! approx_float(
 
 approx_float!(f32)
 approx_float!(f64)
+
+#[macro_export]
+macro_rules! assert_approx_eq_eps(
+    ($given: expr, $expected: expr, $eps: expr) => ({
+        let eps = &($eps);
+        let (given_val, expected_val) = (&($given), &($expected));
+        if !given_val.approx_eq_eps(expected_val, eps) {
+            fail!("assertion failed: `left ≈ right` (left: `{}`, right: `{}`, tolerance: `{}`)",
+                *given_val, *expected_val, *eps
+            )
+        }
+    })
+)
+
+#[macro_export]
+macro_rules! assert_approx_eq(
+    ($given: expr, $expected: expr) => ({
+        let (given_val, expected_val) = (&($given), &($expected));
+        if !given_val.approx_eq(expected_val) {
+            fail!("assertion failed: `left ≈ right` (left: `{}`, right: `{}`, tolerance: `{}`)",
+                *given_val, *expected_val,
+                ApproxEq::approx_epsilon(Some(*given_val))
+            )
+        }
+    })
+)
diff --git a/tests/approx.rs b/tests/approx.rs
new file mode 100644
index 0000000..38157f1
--- /dev/null
+++ b/tests/approx.rs
@@ -0,0 +1,44 @@
+// Copyright 2014 The CGMath Developers. For a full listing of the authors,
+// refer to the AUTHORS file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#![feature(globs)]
+#![feature(phase)]
+
+#[phase(plugin, link)]
+extern crate cgmath;
+
+use cgmath::*;
+
+#[test]
+fn macro_assert_approx_eq_eps() {
+    assert_approx_eq_eps!(1.0f64, 1.001, 0.01);
+}
+
+#[test]
+#[should_fail]
+fn macro_assert_approx_eq_eps_fail() {
+    assert_approx_eq_eps!(1.0f32, 1.02, 0.01);
+}
+
+#[test]
+fn macro_assert_approx_eq() {
+    assert_approx_eq!(7.0f32 / 5.0, 1.4);
+}
+
+#[test]
+#[should_fail]
+fn macro_assert_approx_eq_fail() {
+    assert_approx_eq!(1.0f64 / 3.0, 0.333);
+}