Fix recent changes calculation

main.go

@@ -398,6 +398,7 @@ func (h *indexHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, err.Error(), 500)
 		return
 	}
+
 }
 
 func (h *recentHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
@@ -429,24 +430,7 @@ func (h *recentHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 	// group recentchanges on Page
 	if len(changes) > 0 {
-		f := len(changes) - 1
+		f := groupRecentChanges(changes)
-		i := f
-
-		for {
-			if changes[f].Page == changes[i].Page && changes[f].Date.Truncate(24*time.Hour) == changes[i].Date.Truncate(24*time.Hour) {
-				changes[f].Count++
-				i--
-			} else {
-				changes[f].EndDate = changes[i+1].Date
-				f--
-				changes[f] = changes[i]
-			}
-
-			if i <= 0 {
-				break
-			}
-		}
-
 		changes = changes[f:]
 	}
 

recent.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"time"
+)
+
+func combine(x, y Change) Change {
+	x.Count++
+	if x.Body == "" {
+		x.Body = y.Body
+	} else {
+		x.Body += " " + y.Body
+	}
+	x.EndDate = y.Date
+
+	return x
+}
+
+func changeEqual(x, y Change) bool {
+	return x.Page == y.Page && x.Date.Truncate(24*time.Hour) == y.Date.Truncate(24*time.Hour)
+}
+
+func groupRecentChanges(changes []Change) int {
+	if len(changes) <= 1 {
+		return 0
+	}
+
+	f := len(changes) - 1
+	i := f - 1
+
+	for {
+		if changeEqual(changes[f], changes[i]) {
+			changes[f] = combine(changes[f], changes[i])
+		} else {
+			f--
+		}
+
+		if i <= 0 {
+			break
+		}
+
+		i--
+	}
+
+	return f
+}

recent_test.go

@@ -0,0 +1,102 @@
+package main
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGroupNoRecentChanges(t *testing.T) {
+	changes := []Change{}
+	f := groupRecentChanges(changes)
+	assert.Equal(t, 0, f, "should return 0")
+}
+
+func TestGroupOneRecentChange(t *testing.T) {
+	changes := []Change{
+		Change{
+			Page: "Home",
+			Date: time.Now(),
+			Body: "test",
+		},
+	}
+	f := groupRecentChanges(changes)
+	assert.Equal(t, 0, f, "should return 0")
+	assert.Equal(t, "Home", changes[0].Page, "change should not have changed")
+	assert.Equal(t, "test", changes[0].Body, "change should not have changed")
+	assert.Equal(t, 0, changes[0].Count, "change should not have changed")
+}
+
+func TestGroupTwoDiffRecentChanges(t *testing.T) {
+	d1, err := time.Parse(time.RFC3339, "2019-01-01T10:00:00Z")
+	assert.NoError(t, err, "should parse first date")
+
+	d2, err := time.Parse(time.RFC3339, "2019-02-02T11:00:00Z")
+	assert.NoError(t, err, "should parse second date")
+
+	changes := []Change{
+		Change{
+			Page: "Home",
+			Date: d2,
+			Body: "summary 2",
+		},
+		Change{
+			Page: "Home",
+			Date: d1,
+			Body: "summary 1",
+		},
+	}
+
+	f := groupRecentChanges(changes)
+
+	assert.Equal(t, 0, f, "should new position of first element")
+
+	assert.Equal(t, "Home", changes[0].Page, "change should not have changed")
+	assert.Equal(t, "summary 2", changes[0].Body, "change should not have changed")
+	assert.Equal(t, 0, changes[0].Count, "change should not have changed")
+
+	assert.Equal(t, "Home", changes[1].Page, "change should not have changed")
+	assert.Equal(t, "summary 1", changes[1].Body, "change should not have changed")
+	assert.Equal(t, 0, changes[1].Count, "change should not have changed")
+}
+
+func TestGroupTwoRecentChanges(t *testing.T) {
+	d1, err := time.Parse(time.RFC3339, "2019-01-01T10:00:00Z")
+	assert.NoError(t, err, "should parse first date")
+	d2, err := time.Parse(time.RFC3339, "2019-01-01T11:00:00Z")
+	assert.NoError(t, err, "should parse second date")
+	changes := []Change{
+		Change{
+			Page: "Home",
+			Date: d2,
+			Body: "summary 2",
+		},
+		Change{
+			Page: "Home",
+			Date: d1,
+			Body: "summary 1",
+		},
+	}
+	f := groupRecentChanges(changes)
+	assert.Equal(t, 1, f, "should new position of first element")
+	assert.Equal(t, "Home", changes[f].Page, "change should not have changed")
+	assert.Equal(t, "summary 1 summary 2", changes[f].Body, "change should not have changed")
+	assert.Equal(t, 1, changes[f].Count, "change should not have changed")
+}
+
+func TestChangeNotEqual(t *testing.T) {
+	d1, err := time.Parse(time.RFC3339, "2019-01-01T10:00:00Z")
+	assert.NoError(t, err, "should parse first date")
+	d2, err := time.Parse(time.RFC3339, "2019-02-02T11:00:00Z")
+	assert.NoError(t, err, "should parse second date")
+	assert.Equal(t, false, changeEqual(Change{Page: "Home", Date: d1}, Change{Page: "Home", Date: d2}), "compare dates")
+}
+
+func TestChangeEqual(t *testing.T) {
+	d1, err := time.Parse(time.RFC3339, "2019-01-01T10:00:00Z")
+	assert.NoError(t, err, "should parse first date")
+	d2, err := time.Parse(time.RFC3339, "2019-01-01T11:00:00Z")
+	assert.NoError(t, err, "should parse second date")
+	assert.Equal(t, true, changeEqual(Change{Page: "Home", Date: d1}, Change{Page: "Home", Date: d2}), "compare dates")
+}