Merge e9cd2c6 into b0d2519

composition/content_merge.go

@@ -60,7 +60,8 @@ func (cntx *ContentMerge) collectStylesheets(f Fragment) {
 }
 
 func (cntx *ContentMerge) writeStylesheets(w io.Writer) {
-	for _, attrs := range cntx.stylesheets {
+	stylesheets := stylesheetDeduplicationStrategy.Deduplicate(cntx.stylesheets)
+	for _, attrs := range stylesheets {
 		joinedAttr := joinAttrs(attrs)
 		stylesheet := fmt.Sprintf("\n    <link %s>", joinedAttr)
 		io.WriteString(w, stylesheet)

composition/content_merge_test.go

@@ -8,11 +8,6 @@ import (
 	"golang.org/x/net/html"
 )
 
-func stylesheetAttrs(href string) []html.Attribute {
-	commonAttr := []html.Attribute{{Key: "rel", Val: "stylesheet"}, {Key: "type", Val: "text/css"}}
-	return append(commonAttr, html.Attribute{Key: "href", Val: href})
-}
-
 func Test_ContentMerge_PositiveCase(t *testing.T) {
 	a := assert.New(t)
 

composition/interfaces.go

@@ -124,3 +124,7 @@ type Cache interface {
 	Invalidate()
 	PurgeEntries(keys []string)
 }
+
+type StylesheetDeduplicationStrategy interface {
+	Deduplicate(stylesheetAttrs [][]html.Attribute) [][]html.Attribute
+}

composition/stylesheet_deduplication.go

@@ -0,0 +1,53 @@
+package composition
+
+import (
+	"strings"
+
+	"golang.org/x/net/html"
+)
+
+// Initialization: Sets the default deduplication strategy to be used.
+func init() {
+	SetStrategy(new(IdentityDeduplicationStrategy))
+}
+
+// Set another deduplication strategy.
+func SetStrategy(strategy StylesheetDeduplicationStrategy) {
+	stylesheetDeduplicationStrategy = strategy
+}
+
+// NOOP strategy.
+// This stragegy will insert all found stylesheets w/o any filtering.
+type IdentityDeduplicationStrategy struct {
+}
+
+func (strategy *IdentityDeduplicationStrategy) Deduplicate(stylesheets [][]html.Attribute) [][]html.Attribute {
+	return stylesheets
+}
+
+// Simple strategy
+// Implements a very simple deduplication stragegy. That is, it filters out
+// stylesheets with duplicate href value.
+type SimpleDeduplicationStrategy struct {
+}
+
+// Remove duplicate entries from hrefs.
+func (strategy *SimpleDeduplicationStrategy) Deduplicate(stylesheets [][]html.Attribute) (result [][]html.Attribute) {
+	var knownHrefs string
+	const delimiter = "-|-"
+	for _, stylesheetAttrs := range stylesheets {
+		hrefAttr, attrExists := getAttr(stylesheetAttrs, "href")
+		if !attrExists {
+			continue
+		}
+		href := hrefAttr.Val
+		if !strings.Contains(knownHrefs, href) {
+			result = append(result, stylesheetAttrs)
+			knownHrefs += delimiter + href
+		}
+	}
+	return result
+}
+
+// Variable to hold the active strategy
+var stylesheetDeduplicationStrategy StylesheetDeduplicationStrategy

composition/stylesheet_deduplication_test.go

@@ -0,0 +1,75 @@
+package composition
+
+import (
+	"testing"
+
+	"golang.org/x/net/html"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func stylesheetAttrs(href string) []html.Attribute {
+	commonAttr := []html.Attribute{{Key: "rel", Val: "stylesheet"}, {Key: "type", Val: "text/css"}}
+	return append(commonAttr, html.Attribute{Key: "href", Val: href})
+}
+
+func Test_DefaultDeduplicationStrategy(t *testing.T) {
+	a := assert.New(t)
+	stylesheets := [][]html.Attribute{stylesheetAttrs("/a"), stylesheetAttrs("/b")}
+	result := stylesheetDeduplicationStrategy.Deduplicate(stylesheets)
+	a.EqualValues(stylesheets, result)
+}
+
+func Test_SimpleDeduplicationStrategy(t *testing.T) {
+	a := assert.New(t)
+	stylesheets := [][]html.Attribute{
+		stylesheetAttrs("/a"),
+		stylesheetAttrs("/b"),
+		stylesheetAttrs("/a"),
+		stylesheetAttrs("/b"),
+		stylesheetAttrs("/c"),
+		stylesheetAttrs("/a"),
+	}
+	expected := [][]html.Attribute{
+		stylesheetAttrs("/a"),
+		stylesheetAttrs("/b"),
+		stylesheetAttrs("/c"),
+	}
+	deduper := new(SimpleDeduplicationStrategy)
+	result := deduper.Deduplicate(stylesheets)
+	a.EqualValues(expected, result)
+}
+
+// Tests for setting an own deduplication strategy
+type Strategy struct {
+}
+
+func (strategy *Strategy) Deduplicate(stylesheets [][]html.Attribute) (result [][]html.Attribute) {
+	for i, stylesheetAttrs := range stylesheets {
+		if i%2 == 0 {
+			result = append(result, stylesheetAttrs)
+		}
+	}
+	return result
+}
+
+func Test_OwnDeduplicationStrategy(t *testing.T) {
+	strategy := new(Strategy)
+	SetStrategy(strategy)
+
+	a := assert.New(t)
+	stylesheets := [][]html.Attribute{
+		stylesheetAttrs("/a"),
+		stylesheetAttrs("/b"),
+		stylesheetAttrs("/c"),
+		stylesheetAttrs("/d"),
+		stylesheetAttrs("/e"),
+	}
+	expected := [][]html.Attribute{
+		stylesheetAttrs("/a"),
+		stylesheetAttrs("/c"),
+		stylesheetAttrs("/e"),
+	}
+	result := stylesheetDeduplicationStrategy.Deduplicate(stylesheets)
+	a.EqualValues(expected, result)
+}

composition_example/example_ui_service_test.go

@@ -28,10 +28,6 @@ func Test_integration_test(t *testing.T) {
 	expected, err := ioutil.ReadFile("./expected_test_result.html")
 	expectedS := strings.Replace(string(expected), "http://127.0.0.1:8080", s.URL, -1)
 
-	// debug - don't commit!
-	ioutil.WriteFile("/tmp/expected", []byte(expectedS), 0644)
-	ioutil.WriteFile("/tmp/result", body, 0644)
-
 	a.NoError(err)
 	htmlEqual(t, expectedS, string(body))
 }