fileserver: Share template logic for both templates and file_server browse (#4093)

Co-authored-by: Matthew Holt <mholt@users.noreply.github.com>

modules/caddyhttp/fileserver/browsetplcontext_test.go

@@ -0,0 +1,54 @@
+// Copyright 2015 Matthew Holt and The Caddy Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package fileserver
+
+import (
+	"testing"
+)
+
+func TestBreadcrumbs(t *testing.T) {
+	testdata := []struct {
+		path     string
+		expected []crumb
+	}{
+		{"", []crumb{}},
+		{"/", []crumb{{Text: "/"}}},
+		{"foo/bar/baz", []crumb{
+			{Link: "../../", Text: "foo"},
+			{Link: "../", Text: "bar"},
+			{Link: "", Text: "baz"},
+		}},
+		{"/qux/quux/corge/", []crumb{
+			{Link: "../../../", Text: "/"},
+			{Link: "../../", Text: "qux"},
+			{Link: "../", Text: "quux"},
+			{Link: "", Text: "corge"},
+		}},
+	}
+
+	for _, d := range testdata {
+		l := browseTemplateContext{Path: d.path}
+		actual := l.Breadcrumbs()
+		if len(actual) != len(d.expected) {
+			t.Errorf("wrong size output, got %d elements but expected %d", len(actual), len(d.expected))
+			continue
+		}
+		for i, c := range actual {
+			if c != d.expected[i] {
+				t.Errorf("got %#v but expected %#v at index %d", c, d.expected[i], i)
+			}
+		}
+	}
+}