Expose range information for markdown text nodes [WIP] (#9067)

* Track positions of markdown text

* Add tests for markdown text ranges

utils/markdown/text_range_test.go

@@ -0,0 +1,110 @@
+// Copyright (c) 2018-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package markdown
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTextRanges(t *testing.T) {
+	for name, tc := range map[string]struct {
+		Markdown       string
+		ExpectedRanges []Range
+		ExpectedValues []string
+	}{
+		"simple": {
+			Markdown:       "hello",
+			ExpectedRanges: []Range{{0, 5}},
+			ExpectedValues: []string{"hello"},
+		},
+		"simple2": {
+			Markdown:       "hello!",
+			ExpectedRanges: []Range{{0, 5}, {5, 6}},
+			ExpectedValues: []string{"hello", "!"},
+		},
+		"multiline": {
+			Markdown:       "hello world\nfoobar",
+			ExpectedRanges: []Range{{0, 11}, {12, 18}},
+			ExpectedValues: []string{"hello world", "foobar"},
+		},
+		"code": {
+			Markdown:       "hello `code` world",
+			ExpectedRanges: []Range{{0, 6}, {12, 18}},
+			ExpectedValues: []string{"hello ", " world"},
+		},
+		"notcode": {
+			Markdown:       "hello ` world",
+			ExpectedRanges: []Range{{0, 6}, {6, 7}, {7, 13}},
+			ExpectedValues: []string{"hello ", "`", " world"},
+		},
+		"escape": {
+			Markdown:       "\\*hello\\*",
+			ExpectedRanges: []Range{{1, 2}, {2, 7}, {8, 9}},
+			ExpectedValues: []string{"*", "hello", "*"},
+		},
+		"escapeescape": {
+			Markdown:       "\\\\",
+			ExpectedRanges: []Range{{1, 2}},
+			ExpectedValues: []string{"\\"},
+		},
+		"notescape": {
+			Markdown:       "foo\\x",
+			ExpectedRanges: []Range{{0, 3}, {3, 4}, {4, 5}},
+			ExpectedValues: []string{"foo", "\\", "x"},
+		},
+		"notlink": {
+			Markdown:       "[foo",
+			ExpectedRanges: []Range{{0, 1}, {1, 4}},
+			ExpectedValues: []string{"[", "foo"},
+		},
+		"notlinkend": {
+			Markdown:       "[foo]",
+			ExpectedRanges: []Range{{0, 1}, {1, 4}, {4, 5}},
+			ExpectedValues: []string{"[", "foo", "]"},
+		},
+		"notimage": {
+			Markdown:       "![foo",
+			ExpectedRanges: []Range{{0, 2}, {2, 5}},
+			ExpectedValues: []string{"![", "foo"},
+		},
+		"notimage2": {
+			Markdown:       "!foo",
+			ExpectedRanges: []Range{{0, 1}, {1, 4}},
+			ExpectedValues: []string{"!", "foo"},
+		},
+		"charref": {
+			Markdown:       ""test",
+			ExpectedRanges: []Range{{0, 1}, {6, 10}},
+			ExpectedValues: []string{"\"", "test"},
+		},
+		"notcharref": {
+			Markdown:       "&amp test",
+			ExpectedRanges: []Range{{0, 1}, {1, 9}},
+			ExpectedValues: []string{"&", "amp test"},
+		},
+		"notcharref2": {
+			Markdown:       "&mattermost;",
+			ExpectedRanges: []Range{{0, 1}, {1, 12}},
+			ExpectedValues: []string{"&", "mattermost;"},
+		},
+	} {
+		t.Run(name, func(t *testing.T) {
+			var ranges []Range
+			var values []string
+			Inspect(tc.Markdown, func(node interface{}) bool {
+				if textNode, ok := node.(*Text); ok {
+					ranges = append(ranges, textNode.Range)
+					values = append(values, textNode.Text)
+				}
+				return true
+			})
+			assert.Equal(t, ranges, tc.ExpectedRanges)
+			assert.Equal(t, values, tc.ExpectedValues)
+
+		})
+	}
+
+}