internal/report: report errors with persistent backing

This is useful for reporting errors from processes that must never terminate.

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

internal/report/report_test.go

@@ -0,0 +1,168 @@
+package report_test
+
+import (
+	"bytes"
+	"encoding/gob"
+	"errors"
+	"log"
+	"os"
+	"reflect"
+	"slices"
+	"testing"
+
+	"hakurei.app/check"
+	"hakurei.app/internal/report"
+	"hakurei.app/internal/stub"
+)
+
+func init() { gob.Register(stub.UniqueError(0)) }
+
+func TestDispatch(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		name string
+		flag uint64
+		errs []report.Error
+
+		persist   bool
+		wantLog   string
+		wantPanic error
+	}{
+		{"default", 0, []report.Error{
+			{
+				Severity: report.Fatal,
+				Message:  "rejecting coldboot loop",
+				Err:      stub.UniqueError(0xcafe),
+			},
+		}, true, "dispatch: rejecting coldboot loop: unique error 51966 injected by the test suite\n", nil},
+
+		{"strict", report.DStrict, []report.Error{
+			{
+				Severity: report.Fatal,
+				Message:  "rejecting coldboot loop",
+				Err:      stub.UniqueError(0xcafe),
+			},
+		}, true, "dispatch: rejecting coldboot loop: unique error 51966 injected by the test suite\n", report.Error{
+			Severity: report.Fatal,
+			Message:  "rejecting coldboot loop",
+			Err:      stub.UniqueError(0xcafe),
+		}},
+
+		{"early", 0, []report.Error{
+			{
+				Severity: report.Fatal,
+				Message:  "rejecting coldboot loop",
+				Err:      stub.UniqueError(0xcafe),
+			},
+		}, false, "dispatch: rejecting coldboot loop: unique error 51966 injected by the test suite\n", report.Error{
+			Severity: report.Fatal,
+			Message:  "rejecting coldboot loop",
+			Err:      stub.UniqueError(0xcafe),
+		}},
+
+		{"bypass early", report.DBypassEarly, []report.Error{
+			{
+				Severity: report.Fatal,
+				Message:  "rejecting coldboot loop",
+				Err:      stub.UniqueError(0xcafe),
+			},
+		}, false, "dispatch: rejecting coldboot loop: unique error 51966 injected by the test suite\n", nil},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			var r report.Reporter
+			r.SetFlags(tc.flag)
+			var buf bytes.Buffer
+			l := log.New(&buf, "dispatch: ", 0)
+			r.SetOutput(l)
+
+			a := check.MustAbs(t.TempDir())
+			if tc.persist {
+				r.SetPathname(a)
+			}
+
+			var got []report.Error
+			r.Notify(func(p report.Error) { got = append(got, p) })
+
+			var gotPanic any
+			func() {
+				defer func() { gotPanic = recover() }()
+				for _, p := range tc.errs {
+					r.Dispatch(p.Severity, p.Message, p.Err)
+				}
+			}()
+
+			if gotPanic == nil && !reflect.DeepEqual(got, tc.errs) {
+				t.Errorf("Dispatch: %#v, want %#v", got, tc.errs)
+			}
+			if !reflect.DeepEqual(gotPanic, tc.wantPanic) {
+				t.Errorf("Dispatch: panic = %v, want %v", gotPanic, tc.wantPanic)
+			}
+			if gotLog := buf.String(); gotLog != tc.wantLog {
+				t.Errorf("Dispatch: log =\n%s\nwant\n%s", gotLog, tc.wantLog)
+			}
+
+			if tc.persist {
+				var names []string
+				if dents, err := os.ReadDir(a.String()); err != nil {
+					t.Fatal(err)
+				} else {
+					names = make([]string, len(dents))
+					for i, dent := range dents {
+						names[i] = dent.Name()
+					}
+					slices.Sort(names)
+				}
+
+				gotPersist := make([]report.Error, len(names))
+				for i, name := range names {
+					f, err := os.Open(a.Append(name).String())
+					if err != nil {
+						t.Fatal(err)
+					}
+
+					if err = gob.NewDecoder(f).Decode(&gotPersist[i]); err != nil {
+						_ = f.Close()
+						t.Fatal(err)
+					} else if err = f.Close(); err != nil {
+						t.Fatal(err)
+					}
+				}
+
+				if !reflect.DeepEqual(gotPersist, tc.errs) {
+					t.Errorf("Dispatch: persist = %#v, want %#v", gotPersist, tc.errs)
+				}
+			}
+		})
+	}
+}
+
+func TestBadPersist(t *testing.T) {
+	t.Parallel()
+
+	var r report.Reporter
+	r.SetFlags(report.DNoRecover)
+	r.SetPathname(check.MustAbs("/proc/nonexistent"))
+
+	var pathError *os.PathError
+	func() {
+		defer func() {
+			if !errors.As(recover().(error), &pathError) {
+				t.Fatal("invalid panic kind")
+			}
+		}()
+		r.Dispatch(report.Fatal, "\x00", stub.UniqueError(0xbad))
+	}()
+	if !errors.Is(pathError.Err, os.ErrNotExist) {
+		t.Fatalf("Dispatch: panic = %v", pathError)
+	}
+
+	var buf bytes.Buffer
+	l := log.New(&buf, "persist: ", 0)
+	r.SetOutput(l)
+	r.SetFlags(0)
+	r.Dispatch(report.Fatal, "\x00", stub.UniqueError(0xbad))
+}