Use swarming in create_pagesets CT task

ct/go/util/util_test.go

 package util
 
 import (
         "fmt"
         "io/ioutil"
         "os"
         "path/filepath"
         "strconv"
+        "strings"
         "testing"
 
         "go.skia.org/infra/go/util"
 )
 
 import (
         assert "github.com/stretchr/testify/require"
 )
 
 const (
@@ skipping 59 matching lines @@
 
         // Assert error returned when specified dir does not exist.
         nonexistantDir := filepath.Join(os.TempDir(), "util_test_nonexistant")
         util.RemoveAll(nonexistantDir)
         if err := CreateTimestampFile(nonexistantDir); err != nil {
                 // Expected error
         } else {
                 t.Error("Unexpected lack of error")
         }
 }
+
+func TestGetStartRange(t *testing.T) {
+        assert.Equal(t, 1, GetStartRange(1, 1000))
+        assert.Equal(t, 2001, GetStartRange(3, 1000))
+        assert.Equal(t, 41, GetStartRange(3, 20))
+}
+
+func TestGetPathToPyFiles(t *testing.T) {
+        swarmingPath := GetPathToPyFiles(true)
+        assert.True(t, strings.HasSuffix(swarmingPath, filepath.Join("src", "go.skia.org", "infra", "ct", "py")))
+        nonSwarmingPath := GetPathToPyFiles(false)
+        assert.True(t, strings.HasSuffix(nonSwarmingPath, filepath.Join("src", "go.skia.org", "infra", "ct", "py")))
+}