std: enable FailingAllocator to fail on resize

Now that allocator.resize() is allowed to fail, programs may wish to
test code paths that handle resize() failure. The simplest way to do
this now is to replace the vtable of the testing allocator with one
that uses Allocator.noResize for the 'resize' function pointer.

An alternative way to support this testing capability is to augment the
FailingAllocator (which is already useful for testing allocation failure
scenarios) to intentionally fail on calls to resize(). To do this, add a
'resize_fail_index' parameter to the FailingAllocator that causes
resize() to fail after the given number of calls.

1 files changed, 4 insertions, 4 deletions

diff --git a/lib/std/testing.zig b/lib/std/testing.zig
index 40a95a450b..17ac0d4b04 100644
--- a/lib/std/testing.zig
+++ b/lib/std/testing.zig
@@ -14,7 +14,7 @@ pub var allocator_instance = b: {
 };
 
 pub const failing_allocator = failing_allocator_instance.allocator();
-pub var failing_allocator_instance = FailingAllocator.init(base_allocator_instance.allocator(), 0);
+pub var failing_allocator_instance = FailingAllocator.init(base_allocator_instance.allocator(), .{ .fail_index = 0 });
 
 pub var base_allocator_instance = std.heap.FixedBufferAllocator.init("");
 
@@ -1081,16 +1081,16 @@ pub fn checkAllAllocationFailures(backing_allocator: std.mem.Allocator, comptime
 
     // Try it once with unlimited memory, make sure it works
     const needed_alloc_count = x: {
-        var failing_allocator_inst = std.testing.FailingAllocator.init(backing_allocator, std.math.maxInt(usize));
+        var failing_allocator_inst = std.testing.FailingAllocator.init(backing_allocator, .{});
         args.@"0" = failing_allocator_inst.allocator();
 
         try @call(.auto, test_fn, args);
-        break :x failing_allocator_inst.index;
+        break :x failing_allocator_inst.alloc_index;
     };
 
     var fail_index: usize = 0;
     while (fail_index < needed_alloc_count) : (fail_index += 1) {
-        var failing_allocator_inst = std.testing.FailingAllocator.init(backing_allocator, fail_index);
+        var failing_allocator_inst = std.testing.FailingAllocator.init(backing_allocator, .{ .fail_index = fail_index });
         args.@"0" = failing_allocator_inst.allocator();
 
         if (@call(.auto, test_fn, args)) |_| {