Add a bit nicer assertion helper in testutil/testlogger.

This makes output that's easier to copy-paste into the test. We could also make it ignore the order of key/value pairs in the future.

Signed-off-by: Matt Moyer <moyerm@vmware.com>

internal/testutil/testlogger/testlogger.go

@@ -6,6 +6,7 @@ package testlogger
 
 import (
 	"bytes"
+	"fmt"
 	"log"
 	"strings"
 	"sync"
@@ -13,6 +14,7 @@ import (
 
 	"github.com/go-logr/logr"
 	"github.com/go-logr/stdr"
+	"github.com/stretchr/testify/require"
 )
 
 // Logger implements logr.Logger in a way that captures logs for test assertions.
@@ -46,6 +48,12 @@ func (l *Logger) Lines() []string {
 	return result
 }
 
+// Expect the emitted lines to match known-good output.
+func (l *Logger) Expect(expected []string) {
+	actual := l.Lines()
+	require.Equalf(l.t, expected, actual, "did not see expected log output, actual output:\n%#v", backtickStrings(actual))
+}
+
 // syncBuffer synchronizes access to a bytes.Buffer.
 type syncBuffer struct {
 	mutex  sync.Mutex
@@ -57,3 +65,18 @@ func (s *syncBuffer) Write(p []byte) (n int, err error) {
 	defer s.mutex.Unlock()
 	return s.buffer.Write(p)
 }
+
+type backtickStrings []string
+
+func (b backtickStrings) GoString() string {
+	lines := make([]string, 0, len(b))
+	for _, s := range b {
+		if strings.Contains(s, "`") {
+			s = fmt.Sprintf("%#v", s)
+		} else {
+			s = fmt.Sprintf("`%s`", s)
+		}
+		lines = append(lines, fmt.Sprintf("\t%s,", s))
+	}
+	return fmt.Sprintf("[]string{\n%s\n}", strings.Join(lines, "\n"))
+}