Adding upstream version 2.6.3.

Signed-off-by: Daniel Baumann <daniel@debian.org>

internal/assert/assert.go

@@ -0,0 +1,22 @@
+package assert
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func Equal(t *testing.T, x, y interface{}) {
+	t.Helper()
+
+	r := DiffReporter{}
+	if !cmp.Equal(x, y, cmp.Reporter(&r)) {
+		t.Error(r.String())
+	}
+}
+
+func Nil(t *testing.T, x interface{}) {
+	t.Helper()
+
+	Equal(t, x, nil)
+}

internal/assert/diff_reporter.go

@@ -0,0 +1,36 @@
+// this code is from the examples
+// https://pkg.go.dev/github.com/google/go-cmp/cmp?tab=doc#Reporter
+package assert
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+// DiffReporter is a simple custom reporter that only records differences
+// detected during comparison.
+type DiffReporter struct {
+	path  cmp.Path
+	diffs []string
+}
+
+func (r *DiffReporter) PushStep(ps cmp.PathStep) {
+	r.path = append(r.path, ps)
+}
+
+func (r *DiffReporter) Report(rs cmp.Result) {
+	if !rs.Equal() {
+		vx, vy := r.path.Last().Values()
+		r.diffs = append(r.diffs, fmt.Sprintf("%#v:\n\t-: %+v\n\t+: %+v\n", r.path, vx, vy))
+	}
+}
+
+func (r *DiffReporter) PopStep() {
+	r.path = r.path[:len(r.path)-1]
+}
+
+func (r *DiffReporter) String() string {
+	return strings.Join(r.diffs, "\n")
+}