dashboard/app: test coverage /file link

1. Init 1 coveragedb client per AppEngine instance.
2. Always init coverage handlers. It simplifies testing.
3. Read webGit from ctx to make it mockable.
4. Read coveragedb client from ctx to make it mockable.
5. Use int for file line number and int64 for merged coverage.

Makefile

@@ -236,6 +236,7 @@ generate_go: format_cpp
 	$(GO) generate ./executor ./pkg/ifuzz ./pkg/build ./pkg/rpcserver
 	$(GO) generate ./vm/proxyapp
 	$(GO) generate ./pkg/coveragedb
+	$(GO) generate ./pkg/covermerger
 
 generate_rpc:
 	flatc -o pkg/flatrpc --warnings-as-errors --gen-object-api --filename-suffix "" --go --gen-onefile --go-namespace flatrpc pkg/flatrpc/flatrpc.fbs

dashboard/app/config.go

@@ -425,6 +425,7 @@ func installConfig(cfg *GlobalConfig) {
 	initAPIHandlers()
 	initKcidb()
 	initBatchProcessors()
+	initCoverageDB()
 }
 
 var contextConfigKey = "Updated config (to be used during tests). Use only in tests!"

dashboard/app/coverage.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"html/template"
 	"net/http"
+	"os"
 	"slices"
 	"strconv"
 
@@ -17,8 +18,25 @@ import (
 	"github.com/google/syzkaller/pkg/coveragedb/spannerclient"
 	"github.com/google/syzkaller/pkg/covermerger"
 	"github.com/google/syzkaller/pkg/validator"
+	"golang.org/x/exp/maps"
 )
 
+var coverageDBClient spannerclient.SpannerClient
+
+func initCoverageDB() {
+	projectID := os.Getenv("GOOGLE_CLOUD_PROJECT")
+	if projectID == "" {
+		// It is a test environment.
+		// Use SetCoverageDBClient to specify the coveragedb mock or emulator in every test.
+		return
+	}
+	var err error
+	coverageDBClient, err = spannerclient.NewClient(context.Background(), projectID)
+	if err != nil {
+		panic("spanner.NewClient: " + err.Error())
+	}
+}
+
 type funcStyleBodyJS func(
 	ctx context.Context, client spannerclient.SpannerClient,
 	scope *cover.SelectScope, onlyUnique bool, sss, managers []string,
@@ -37,6 +55,10 @@ func handleHeatmap(c context.Context, w http.ResponseWriter, r *http.Request, f
 	if err != nil {
 		return err
 	}
+	nsConfig := getNsConfig(c, hdr.Namespace)
+	if nsConfig.Coverage == nil {
+		return ErrClientNotFound
+	}
 	ss := r.FormValue("subsystem")
 	manager := r.FormValue("manager")
 
@@ -127,7 +149,8 @@ func handleFileCoverage(c context.Context, w http.ResponseWriter, r *http.Reques
 	targetCommit := r.FormValue("commit")
 	kernelFilePath := r.FormValue("filepath")
 	manager := r.FormValue("manager")
-	allowedManagers, err := CachedManagerList(c, hdr.Namespace)
+	// It is easier to test than the CachedManagerList.
+	allowedManagers := maps.Keys(nsConfig.Managers)
 	if err != nil {
 		return fmt.Errorf("CachedManagerList: %w", err)
 	}
@@ -150,24 +173,31 @@ func handleFileCoverage(c context.Context, w http.ResponseWriter, r *http.Reques
 	}
 	onlyUnique := r.FormValue("unique-only") == "1"
 	mainNsRepo, _ := nsConfig.mainRepoBranch()
-	hitLines, hitCounts, err := coveragedb.ReadLinesHitCount(c, hdr.Namespace, targetCommit, manager, kernelFilePath, tp)
+	hitLines, hitCounts, err := coveragedb.ReadLinesHitCount(c, hdr.Namespace, targetCommit, kernelFilePath, manager, tp)
 	covMap := cover.MakeCovMap(hitLines, hitCounts)
 	if err != nil {
 		return fmt.Errorf("coveragedb.ReadLinesHitCount(%s): %w", manager, err)
 	}
 	if onlyUnique {
-		allHitLines, allHitCounts, err := coveragedb.ReadLinesHitCount(c, hdr.Namespace, targetCommit, manager, kernelFilePath, tp)
+		// This request is expected to be made second by tests.
+		// Moving it to goroutine don't forget to change multiManagerCovDBFixture.
+		allHitLines, allHitCounts, err := coveragedb.ReadLinesHitCount(c, hdr.Namespace, targetCommit, kernelFilePath, "*", tp)
 		if err != nil {
 			return fmt.Errorf("coveragedb.ReadLinesHitCount(*): %w", err)
 		}
 		covMap = cover.UniqCoverage(cover.MakeCovMap(allHitLines, allHitCounts), covMap)
 	}
 
+	webGit := getWebGit(c) // Get mock if available.
+	if webGit == nil {
+		webGit = covermerger.MakeWebGit(makeProxyURIProvider(nsConfig.Coverage.WebGitURI))
+	}
+
 	content, err := cover.RendFileCoverage(
 		mainNsRepo,
 		targetCommit,
 		kernelFilePath,
-		makeProxyURIProvider(nsConfig.Coverage.WebGitURI),
+		webGit,
 		&covermerger.MergeResult{HitCounts: covMap},
 		cover.DefaultHTMLRenderConfig())
 	if err != nil {
@@ -178,11 +208,26 @@ func handleFileCoverage(c context.Context, w http.ResponseWriter, r *http.Reques
 	return nil
 }
 
+var keyWebGit = "file content provider"
+
+func setWebGit(ctx context.Context, provider covermerger.FileVersProvider) context.Context {
+	return context.WithValue(ctx, &keyWebGit, provider)
+}
+
+func getWebGit(ctx context.Context) covermerger.FileVersProvider {
+	res, _ := ctx.Value(&keyWebGit).(covermerger.FileVersProvider)
+	return res
+}
+
 func handleCoverageGraph(c context.Context, w http.ResponseWriter, r *http.Request) error {
 	hdr, err := commonHeader(c, r, w, "")
 	if err != nil {
 		return err
 	}
+	nsConfig := getNsConfig(c, hdr.Namespace)
+	if nsConfig.Coverage == nil {
+		return ErrClientNotFound
+	}
 	periodType := r.FormValue("period")
 	if periodType == "" {
 		periodType = coveragedb.QuarterPeriod

dashboard/app/coverage_test.go

@@ -0,0 +1,167 @@
+// Copyright 2025 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+package main
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/google/syzkaller/pkg/coveragedb"
+	"github.com/google/syzkaller/pkg/coveragedb/mocks"
+	"github.com/google/syzkaller/pkg/coveragedb/spannerclient"
+	"github.com/google/syzkaller/pkg/covermerger"
+	mergermocks "github.com/google/syzkaller/pkg/covermerger/mocks"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+	"google.golang.org/api/iterator"
+)
+
+func TestFileCoverage(t *testing.T) {
+	tests := []struct {
+		name      string
+		covDB     func(t *testing.T) spannerclient.SpannerClient
+		fileProv  covermerger.FileVersProvider
+		url       string
+		wantInRes []string
+	}{
+		{
+			name:      "empty db",
+			covDB:     func(t *testing.T) spannerclient.SpannerClient { return emptyCoverageDBFixture(t, 1) },
+			fileProv:  staticFileProvider(t),
+			url:       "/test2/graph/coverage/file?dateto=2025-01-31&period=month&commit=c0e75905caf368e19aab585d20151500e750de89&filepath=virt/kvm/kvm_main.c",
+			wantInRes: []string{"1 line1"},
+		},
+		{
+			name:     "regular db",
+			covDB:    func(t *testing.T) spannerclient.SpannerClient { return coverageDBFixture(t) },
+			fileProv: staticFileProvider(t),
+			url:      "/test2/graph/coverage/file?dateto=2025-01-31&period=month&commit=c0e75905caf368e19aab585d20151500e750de89&filepath=virt/kvm/kvm_main.c",
+			wantInRes: []string{
+				"4      1 line1",
+				"5      2 line2",
+				"6      3 line3"},
+		},
+		{
+			name:     "multimanager db",
+			covDB:    func(t *testing.T) spannerclient.SpannerClient { return multiManagerCovDBFixture(t) },
+			fileProv: staticFileProvider(t),
+			url:      "/test2/graph/coverage/file?dateto=2025-01-31&period=month&commit=c0e75905caf368e19aab585d20151500e750de89&filepath=virt/kvm/kvm_main.c&manager=special-cc-manager&unique-only=1",
+			wantInRes: []string{
+				" 0      1 line1", // Covered, is not unique.
+				" 5      2 line2", // Covered and is unique.
+				"        3 line3", // Covered only by "*" managers.
+			},
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			c := NewCtx(t)
+			defer c.Close()
+			c.setCoverageMocks("test2", test.covDB(t), test.fileProv)
+			fileCovPage, err := c.GET(test.url)
+			assert.NoError(t, err)
+			got := string(fileCovPage)
+			for _, want := range test.wantInRes {
+				if !strings.Contains(got, want) {
+					t.Errorf(`"%s" wasn't found in "%s"'`, want, got)
+				}
+			}
+		})
+	}
+}
+
+func staticFileProvider(t *testing.T) covermerger.FileVersProvider {
+	m := mergermocks.NewFileVersProvider(t)
+	m.On("GetFileVersions", mock.Anything, mock.Anything).
+		Return(func(targetFilePath string, repoCommits ...covermerger.RepoCommit,
+		) covermerger.FileVersions {
+			res := covermerger.FileVersions{}
+			for _, rc := range repoCommits {
+				res[rc] = `line1
+line2
+line3`
+			}
+			return res
+		}, nil)
+	return m
+}
+
+func emptyCoverageDBFixture(t *testing.T, times int) spannerclient.SpannerClient {
+	mRowIterator := mocks.NewRowIterator(t)
+	mRowIterator.On("Stop").Return().Times(times)
+	mRowIterator.On("Next").
+		Return(nil, iterator.Done).Times(times)
+
+	mTran := mocks.NewReadOnlyTransaction(t)
+	mTran.On("Query", mock.Anything, mock.Anything).
+		Return(mRowIterator).Times(times)
+
+	m := mocks.NewSpannerClient(t)
+	m.On("Single").
+		Return(mTran).Times(times)
+	return m
+}
+
+func coverageDBFixture(t *testing.T) spannerclient.SpannerClient {
+	mRowIt := newRowIteratorMock(t, []*coveragedb.LinesCoverage{{
+		LinesInstrumented: []int64{1, 2, 3},
+		HitCounts:         []int64{4, 5, 6},
+	}})
+
+	mTran := mocks.NewReadOnlyTransaction(t)
+	mTran.On("Query", mock.Anything, mock.Anything).
+		Return(mRowIt).Once()
+
+	m := mocks.NewSpannerClient(t)
+	m.On("Single").
+		Return(mTran).Once()
+	return m
+}
+
+func multiManagerCovDBFixture(t *testing.T) spannerclient.SpannerClient {
+	mReadFullCoverageTran := mocks.NewReadOnlyTransaction(t)
+	mReadFullCoverageTran.On("Query", mock.Anything, mock.Anything).
+		Return(newRowIteratorMock(t, []*coveragedb.LinesCoverage{{
+			LinesInstrumented: []int64{1, 2, 3},
+			HitCounts:         []int64{4, 5, 6},
+		}})).Once()
+
+	mReadPartialCoverageTran := mocks.NewReadOnlyTransaction(t)
+	mReadPartialCoverageTran.On("Query", mock.Anything, mock.Anything).
+		Return(newRowIteratorMock(t, []*coveragedb.LinesCoverage{{
+			LinesInstrumented: []int64{1, 2},
+			HitCounts:         []int64{3, 5},
+		}})).Once()
+
+	m := mocks.NewSpannerClient(t)
+	// The order matters. Full coverage is fetched second.
+	m.On("Single").
+		Return(mReadPartialCoverageTran).Once()
+	m.On("Single").
+		Return(mReadFullCoverageTran).Once()
+
+	return m
+}
+
+func newRowIteratorMock(t *testing.T, cov []*coveragedb.LinesCoverage,
+) *mocks.RowIterator {
+	m := mocks.NewRowIterator(t)
+	m.On("Stop").Once().Return()
+	for _, item := range cov {
+		mRow := mocks.NewRow(t)
+		mRow.On("ToStruct", mock.Anything).
+			Run(func(args mock.Arguments) {
+				arg := args.Get(0).(*coveragedb.LinesCoverage)
+				*arg = *item
+			}).
+			Return(nil).Once()
+
+		m.On("Next").
+			Return(mRow, nil).Once()
+	}
+
+	m.On("Next").
+		Return(nil, iterator.Done).Once()
+	return m
+}

dashboard/app/handler.go

@@ -15,6 +15,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/google/syzkaller/pkg/coveragedb"
 	"github.com/google/syzkaller/pkg/html"
 	"google.golang.org/appengine/v2"
 	"google.golang.org/appengine/v2/log"
@@ -32,6 +33,7 @@ func handlerWrapper(fn contextHandler) http.Handler {
 func handleContext(fn contextHandler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		c := appengine.NewContext(r)
+		c = coveragedb.SetCoverageDBClient(c, coverageDBClient)
 		c = context.WithValue(c, &currentURLKey, r.URL.RequestURI())
 		authorizedUser, _ := userAccessLevel(currentUser(c), "", getConfig(c))
 		if !authorizedUser {

dashboard/app/main.go

@@ -65,13 +65,11 @@ func initHTTPHandlers() {
 		http.Handle("/"+ns+"/graph/fuzzing", handlerWrapper(handleGraphFuzzing))
 		http.Handle("/"+ns+"/graph/crashes", handlerWrapper(handleGraphCrashes))
 		http.Handle("/"+ns+"/graph/found-bugs", handlerWrapper(handleFoundBugsGraph))
-		if nsConfig.Coverage != nil {
-			http.Handle("/"+ns+"/graph/coverage/file", handlerWrapper(handleFileCoverage))
-			http.Handle("/"+ns+"/graph/coverage", handlerWrapper(handleCoverageGraph))
-			http.Handle("/"+ns+"/graph/coverage_heatmap", handlerWrapper(handleCoverageHeatmap))
-			if nsConfig.Subsystems.Service != nil {
-				http.Handle("/"+ns+"/graph/coverage_subsystems_heatmap", handlerWrapper(handleSubsystemsCoverageHeatmap))
-			}
+		http.Handle("/"+ns+"/graph/coverage/file", handlerWrapper(handleFileCoverage))
+		http.Handle("/"+ns+"/graph/coverage", handlerWrapper(handleCoverageGraph))
+		http.Handle("/"+ns+"/graph/coverage_heatmap", handlerWrapper(handleCoverageHeatmap))
+		if nsConfig.Subsystems.Service != nil {
+			http.Handle("/"+ns+"/graph/coverage_subsystems_heatmap", handlerWrapper(handleSubsystemsCoverageHeatmap))
 		}
 		http.Handle("/"+ns+"/repos", handlerWrapper(handleRepos))
 		http.Handle("/"+ns+"/bug-summaries", handlerWrapper(handleBugSummaries))

dashboard/app/util_test.go

@@ -28,6 +28,9 @@ import (
 	"github.com/google/go-cmp/cmp"
 	"github.com/google/syzkaller/dashboard/api"
 	"github.com/google/syzkaller/dashboard/dashapi"
+	"github.com/google/syzkaller/pkg/coveragedb"
+	"github.com/google/syzkaller/pkg/coveragedb/spannerclient"
+	"github.com/google/syzkaller/pkg/covermerger"
 	"github.com/google/syzkaller/pkg/email"
 	"github.com/google/syzkaller/pkg/subsystem"
 	"google.golang.org/appengine/v2/aetest"
@@ -226,6 +229,20 @@ func (c *Ctx) setSubsystems(ns string, list []*subsystem.Subsystem, rev int) {
 	}
 }
 
+func (c *Ctx) setCoverageMocks(ns string, dbClientMock spannerclient.SpannerClient,
+	fileProvMock covermerger.FileVersProvider) {
+	c.transformContext = func(ctx context.Context) context.Context {
+		newConfig := replaceNamespaceConfig(ctx, ns, func(cfg *Config) *Config {
+			ret := *cfg
+			ret.Coverage = &CoverageConfig{WebGitURI: "test-git"}
+			return &ret
+		})
+		ctxWithSpanner := coveragedb.SetCoverageDBClient(ctx, dbClientMock)
+		ctxWithSpannerAndFileProvider := setWebGit(ctxWithSpanner, fileProvMock)
+		return contextWithConfig(ctxWithSpannerAndFileProvider, newConfig)
+	}
+}
+
 func (c *Ctx) setKernelRepos(ns string, list []KernelRepo) {
 	c.transformContext = func(c context.Context) context.Context {
 		newConfig := replaceNamespaceConfig(c, ns, func(cfg *Config) *Config {

pkg/cover/file.go

@@ -40,10 +40,10 @@ func DefaultHTMLRenderConfig() *CoverageRenderConfig {
 	}
 }
 
-func RendFileCoverage(repo, forCommit, filePath string, proxy covermerger.FuncProxyURI,
+func RendFileCoverage(repo, forCommit, filePath string, fileProvider covermerger.FileVersProvider,
 	mr *covermerger.MergeResult, renderConfig *CoverageRenderConfig) (string, error) {
 	repoCommit := covermerger.RepoCommit{Repo: repo, Commit: forCommit}
-	files, err := covermerger.MakeWebGit(proxy).GetFileVersions(filePath, repoCommit)
+	files, err := fileProvider.GetFileVersions(filePath, repoCommit)
 	if err != nil {
 		return "", fmt.Errorf("failed to GetFileVersions: %w", err)
 	}