container: check output helper functions

The container test suite has always been somewhat inadequate due to the inability of coverage tooling to reach into containers. This has become an excuse for not testing non-container code as well, which lead to the general lack of confidence when working with container code. This change aims to be one of many to address that to some extent.

Signed-off-by: Ophestra <cat@gensokyo.uk>

container/output_test.go

@@ -0,0 +1,110 @@
+package container
+
+import (
+	"reflect"
+	"syscall"
+	"testing"
+)
+
+func TestGetSetOutput(t *testing.T) {
+	{
+		out := GetOutput()
+		t.Cleanup(func() { SetOutput(out) })
+	}
+
+	t.Run("default", func(t *testing.T) {
+		SetOutput(new(stubOutput))
+		if v, ok := GetOutput().(*DefaultMsg); ok {
+			t.Fatalf("SetOutput: got unexpected output %#v", v)
+		}
+		SetOutput(nil)
+		if _, ok := GetOutput().(*DefaultMsg); !ok {
+			t.Fatalf("SetOutput: got unexpected output %#v", GetOutput())
+		}
+	})
+
+	t.Run("stub", func(t *testing.T) {
+		SetOutput(new(stubOutput))
+		if _, ok := GetOutput().(*stubOutput); !ok {
+			t.Fatalf("SetOutput: got unexpected output %#v", GetOutput())
+		}
+	})
+}
+
+func TestWrapErr(t *testing.T) {
+	{
+		out := GetOutput()
+		t.Cleanup(func() { SetOutput(out) })
+	}
+
+	var wrapFp *func(error, ...any) error
+	s := new(stubOutput)
+	SetOutput(s)
+	wrapFp = &s.wrapF
+
+	testCases := []struct {
+		name    string
+		f       func(t *testing.T)
+		wantErr error
+		wantA   []any
+	}{
+		{"suffix nil", func(t *testing.T) {
+			if err := wrapErrSuffix(nil, "\x00"); err != nil {
+				t.Errorf("wrapErrSuffix: %v", err)
+			}
+		}, nil, nil},
+		{"suffix val", func(t *testing.T) {
+			if err := wrapErrSuffix(syscall.ENOTRECOVERABLE, "\x00\x00"); err != syscall.ENOTRECOVERABLE {
+				t.Errorf("wrapErrSuffix: %v", err)
+			}
+		}, syscall.ENOTRECOVERABLE, []any{"\x00\x00", syscall.ENOTRECOVERABLE}},
+		{"self nil", func(t *testing.T) {
+			if err := wrapErrSelf(nil); err != nil {
+				t.Errorf("wrapErrSelf: %v", err)
+			}
+		}, nil, nil},
+		{"self val", func(t *testing.T) {
+			if err := wrapErrSelf(syscall.ENOTRECOVERABLE); err != syscall.ENOTRECOVERABLE {
+				t.Errorf("wrapErrSelf: %v", err)
+			}
+		}, syscall.ENOTRECOVERABLE, []any{"state not recoverable"}},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			var (
+				gotErr error
+				gotA   []any
+			)
+			*wrapFp = func(err error, a ...any) error { gotErr = err; gotA = a; return err }
+
+			tc.f(t)
+			if gotErr != tc.wantErr {
+				t.Errorf("WrapErr: err = %v, want %v", gotErr, tc.wantErr)
+			}
+
+			if !reflect.DeepEqual(gotA, tc.wantA) {
+				t.Errorf("WrapErr: a = %v, want %v", gotA, tc.wantA)
+			}
+		})
+	}
+}
+
+type stubOutput struct {
+	wrapF func(error, ...any) error
+}
+
+func (*stubOutput) IsVerbose() bool            { panic("unreachable") }
+func (*stubOutput) Verbose(...any)             { panic("unreachable") }
+func (*stubOutput) Verbosef(string, ...any)    { panic("unreachable") }
+func (*stubOutput) PrintBaseErr(error, string) { panic("unreachable") }
+func (*stubOutput) Suspend()                   { panic("unreachable") }
+func (*stubOutput) Resume() bool               { panic("unreachable") }
+func (*stubOutput) BeforeExit()                { panic("unreachable") }
+
+func (s *stubOutput) WrapErr(err error, v ...any) error {
+	if s.wrapF == nil {
+		panic("unreachable")
+	}
+	return s.wrapF(err, v...)
+}