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, 5 insertions, 4 deletions

diff --git a/std/lazy_init.zig b/std/lazy_init.zig
index f08c01e874..a09168786b 100644
--- a/std/lazy_init.zig
+++ b/std/lazy_init.zig
@@ -1,6 +1,7 @@
 const std = @import("index.zig");
 const builtin = @import("builtin");
 const assert = std.debug.assert;
+const testing = std.testing;
 const AtomicRmwOp = builtin.AtomicRmwOp;
 const AtomicOrder = builtin.AtomicOrder;
 
@@ -63,12 +64,12 @@ test "std.lazyInit" {
         global_number.resolve();
     }
     if (global_number.get()) |x| {
-        assert(x.* == 1234);
+        testing.expect(x.* == 1234);
     } else {
         @panic("bad");
     }
     if (global_number.get()) |x| {
-        assert(x.* == 1234);
+        testing.expect(x.* == 1234);
     } else {
         @panic("bad");
     }
@@ -80,6 +81,6 @@ test "std.lazyInit(void)" {
     if (global_void.get()) |_| @panic("bad") else {
         global_void.resolve();
     }
-    assert(global_void.get() != null);
-    assert(global_void.get() != null);
+    testing.expect(global_void.get() != null);
+    testing.expect(global_void.get() != null);
 }