Enable clear/purge for failed digests

golden/go/mocks/mocks.go

 package mocks
 
 import (
         "fmt"
         "os"
         "sort"
         "strings"
         "time"
 
         assert "github.com/stretchr/testify/require"
@@ skipping 29 matching lines @@
 
 func (m MockDiffStore) AbsPath(digest []string) map[string]string {
         result := map[string]string{}
         for _, d := range digest {
                 result[d] = "abspath/" + d
         }
         return result
 }
 
 func (m MockDiffStore) UnavailableDigests() map[string]*diff.DigestFailure       { return nil }
-func (m MockDiffStore) PurgeDigests(digests []string, purgeGS bool)              {}
+func (m MockDiffStore) PurgeDigests(digests []string, purgeGS bool) error        { return nil }
 func (m MockDiffStore) SetDigestSets(namedDigestSets map[string]map[string]bool) {}
 
 func NewMockDiffStore() diff.DiffStore {
         return MockDiffStore{}
 }
 
 // Mock the tilestore for GoldenTraces
 func NewMockTileStore(t assert.TestingT, digests [][]string, params []map[string]string, commits []*tiling.Commit) tiling.TileStore {
         // Build the tile from the digests, params and commits.
         traces := map[string]tiling.Trace{}
@@ skipping 81 matching lines @@
 // GetTileStoreFromEnv looks at the TEST_TILE_DIR environement variable for the
 // name of directory that contains tiles. If it's defined it will return a
 // TileStore instance. If the not the calling test will fail.
 func GetTileStoreFromEnv(t assert.TestingT) tiling.TileStore {
         // Get the TEST_TILE environment variable that points to the
         // tile to read.
         tileDir := os.Getenv("TEST_TILE_DIR")
         assert.NotEqual(t, "", tileDir, "Please define the TEST_TILE_DIR environment variable to point to a live tile store.")
         return filetilestore.NewFileTileStore(tileDir, config.DATASET_GOLD, 2*time.Minute)
 }