On Monday, 15 June 2026 at 23:39:29 UTC+1 Tom Limoncelli wrote:
However when I run this on my personal machine (go1.26.4, Macos 26.5.1) the
system goes into an infinite loop until I press CTRL-C.
I can't reproduce, and my system is similar to yours. I don't know what "
go-faketime" is, and I wonder if that's the problem. I'm using go installed
via homebrew.
% go version
go version go1.26.3 darwin/arm64
% cat main_test.go
package main
import (
"testing"
)
type MyStruct struct {
M map[string]string
}
func MyFunc(b bool) {
m := &MyStruct{}
if b {
m.M["foo"] = "foo" // panic. Uninitialized map!
} else {
if m.M == nil {
m.M = map[string]string{}
}
m.M["foo"] = "foo" // no panic
}
}
func TestMyFunc(t *testing.T) {
tests := []struct {
name string
data bool
}{
{"good", false},
{"panic", true},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
MyFunc(tt.data)
})
}
}
% go mod init example
go: creating new go.mod: module example
go: to add module requirements and sums:
go mod tidy
% go mod tidy
% ls -l
total 16
-rw-r--r-- 1 brian staff 26 16 Jun 09:00 go.mod
-rw-r--r-- 1 brian staff 502 16 Jun 09:00 main_test.go
% go test -v .
=== RUN TestMyFunc
=== RUN TestMyFunc/good
=== RUN TestMyFunc/panic
--- FAIL: TestMyFunc (0.00s)
--- PASS: TestMyFunc/good (0.00s)
--- FAIL: TestMyFunc/panic (0.00s)
panic: assignment to entry in nil map [recovered, repanicked]
goroutine 37 [running]:
testing.tRunner.func1.2({0x102ea2ca0, 0x102eecc40})
/opt/homebrew/Cellar/go/1.26.3/libexec/src/testing/testing.go:1974 +0x1a0
testing.tRunner.func1()
/opt/homebrew/Cellar/go/1.26.3/libexec/src/testing/testing.go:1977 +0x318
panic({0x102ea2ca0?, 0x102eecc40?})
/opt/homebrew/Cellar/go/1.26.3/libexec/src/runtime/panic.go:860 +0x12c
example.MyFunc(...)
/Users/brian/tmp/zzz/main_test.go:14
example.TestMyFunc.func1(0x46a78c0626c8?)
/Users/brian/tmp/zzz/main_test.go:33 +0x40
testing.tRunner(0x46a78c0626c8, 0x46a78c030200)
/opt/homebrew/Cellar/go/1.26.3/libexec/src/testing/testing.go:2036 +0xc4
created by testing.(*T).Run in goroutine 35
/opt/homebrew/Cellar/go/1.26.3/libexec/src/testing/testing.go:2101 +0x3a8
FAIL example 0.218s
FAIL
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