1 files changed, 121 insertions, 0 deletions
diff --git a/src/go/doc/example_internal_test.go b/src/go/doc/example_internal_test.go
new file mode 100644
index 0000000..08ddfaf
--- /dev/null
+++ b/src/go/doc/example_internal_test.go
@@ -0,0 +1,121 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package doc
+
+import (
+	"go/parser"
+	"go/token"
+	"reflect"
+	"strconv"
+	"strings"
+	"testing"
+)
+
+func TestImportGroupStarts(t *testing.T) {
+	for _, test := range []struct {
+		name string
+		in   string
+		want []string // paths of group-starting imports
+	}{
+		{
+			name: "one group",
+			in: `package p
+import (
+	"a"
+	"b"
+	"c"
+	"d"
+)
+`,
+			want: []string{"a"},
+		},
+		{
+			name: "several groups",
+			in: `package p
+import (
+	"a"
+
+	"b"
+	"c"
+
+	"d"
+)
+`,
+			want: []string{"a", "b", "d"},
+		},
+		{
+			name: "extra space",
+			in: `package p
+import (
+	"a"
+
+
+	"b"
+	"c"
+
+
+	"d"
+)
+`,
+			want: []string{"a", "b", "d"},
+		},
+		{
+			name: "line comment",
+			in: `package p
+import (
+	"a" // comment
+	"b" // comment
+
+	"c"
+)`,
+			want: []string{"a", "c"},
+		},
+		{
+			name: "named import",
+			in: `package p
+import (
+	"a"
+	n "b"
+
+	m "c"
+	"d"
+)`,
+			want: []string{"a", "c"},
+		},
+		{
+			name: "blank import",
+			in: `package p
+import (
+	"a"
+
+	_ "b"
+
+	_ "c"
+	"d"
+)`,
+			want: []string{"a", "b", "c"},
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			fset := token.NewFileSet()
+			file, err := parser.ParseFile(fset, "test.go", strings.NewReader(test.in), parser.ParseComments)
+			if err != nil {
+				t.Fatal(err)
+			}
+			imps := findImportGroupStarts1(file.Imports)
+			got := make([]string, len(imps))
+			for i, imp := range imps {
+				got[i], err = strconv.Unquote(imp.Path.Value)
+				if err != nil {
+					t.Fatal(err)
+				}
+			}
+			if !reflect.DeepEqual(got, test.want) {
+				t.Errorf("got %v, want %v", got, test.want)
+			}
+		})
+	}
+
+}