package logger import ( "github.com/pkg/errors" "github.com/rs/zerolog" "github.com/stretchr/testify/assert" "io" "testing" ) var writeCalls int type mockedWriter struct { wantErr bool } func (c mockedWriter) Write(p []byte) (int, error) { writeCalls++ if c.wantErr { return -1, errors.New("Expected error") } return len(p), nil } // Tests that a new writer is only used if it actually works. func TestResilientMultiWriter(t *testing.T) { tests := []struct { name string writers []io.Writer }{ { name: "All valid writers", writers: []io.Writer{ mockedWriter { wantErr: false, }, mockedWriter { wantErr: false, }, }, }, { name: "All invalid writers", writers: []io.Writer{ mockedWriter { wantErr: true, }, mockedWriter { wantErr: true, }, }, }, { name: "First invalid writer", writers: []io.Writer{ mockedWriter { wantErr: true, }, mockedWriter { wantErr: false, }, }, }, { name: "First valid writer", writers: []io.Writer{ mockedWriter { wantErr: false, }, mockedWriter { wantErr: true, }, }, }, } for _, tt := range tests { writers := tt.writers multiWriter := resilientMultiWriter{writers} logger := zerolog.New(multiWriter).With().Timestamp().Logger().Level(zerolog.InfoLevel) logger.Info().Msg("Test msg") assert.Equal(t, len(writers), writeCalls) writeCalls = 0 } }