std.debug.assert: remove special case for test builds

Previously, std.debug.assert would `@panic` in test builds,
if the assertion failed. Now, it's always `unreachable`.

This makes release mode test builds more accurately test
the actual code that will be run.

However this requires tests to call `std.testing.expect`
rather than `std.debug.assert` to make sure output is correct.

Here is the explanation of when to use either one, copied from
the assert doc comments:

Inside a test block, it is best to use the `std.testing` module
rather than assert, because assert may not detect a test failure
in ReleaseFast and ReleaseSafe mode. Outside of a test block, assert
is the correct function to use.

closes #1304

1 files changed, 2 insertions, 2 deletions

diff --git a/std/special/compiler_rt/floatuntisf_test.zig b/std/special/compiler_rt/floatuntisf_test.zig
index 7f84c1f963..3a97807066 100644
--- a/std/special/compiler_rt/floatuntisf_test.zig
+++ b/std/special/compiler_rt/floatuntisf_test.zig
@@ -1,9 +1,9 @@
 const __floatuntisf = @import("floatuntisf.zig").__floatuntisf;
-const assert = @import("std").debug.assert;
+const testing = @import("std").testing;
 
 fn test__floatuntisf(a: u128, expected: f32) void {
     const x = __floatuntisf(a);
-    assert(x == expected);
+    testing.expect(x == expected);
 }
 
 test "floatuntisf" {