diff --git a/tools/testtool/commands/test_submission.go b/tools/testtool/commands/test_submission.go
index c608511..42d7020 100644
--- a/tools/testtool/commands/test_submission.go
+++ b/tools/testtool/commands/test_submission.go
@@ -243,8 +243,18 @@ func runTests(testDir, privateRepo, problem string) error {
 		raceBinaries = make(map[string]string)
 	)
 
+	coverageReq := getCoverageRequirements(path.Join(privateRepo, problem))
+	if coverageReq.Enabled {
+		log.Printf("required coverage: %.2f%%", coverageReq.Percent)
+	}
+
+	testListDir := testDir
+	if !coverageReq.Enabled {
+		testListDir = privateRepo
+	}
+
 	//binPkgs, testPkgs := listTestsAndBinaries(filepath.Join(testDir, problem), []string{"-tags", "private", "-mod", "readonly"}) // todo return readonly
-	binPkgs, testPkgs := listTestsAndBinaries(filepath.Join(testDir, problem), []string{"-tags", "private"})
+	binPkgs, testPkgs := listTestsAndBinaries(filepath.Join(testListDir, problem), []string{"-tags", "private"})
 	for binaryPkg := range binPkgs {
 		binPath := filepath.Join(binCache, randomName())
 		binaries[binaryPkg] = binPath
@@ -254,11 +264,6 @@ func runTests(testDir, privateRepo, problem string) error {
 		}
 	}
 
-	coverageReq := getCoverageRequirements(path.Join(privateRepo, problem))
-	if coverageReq.Enabled {
-		log.Printf("required coverage: %.2f%%", coverageReq.Percent)
-	}
-
 	binariesJSON, _ := json.Marshal(binaries)
 
 	for testPkg := range testPkgs {
diff --git a/tools/testtool/commands/test_submission_test.go b/tools/testtool/commands/test_submission_test.go
index 8a64296..36b7340 100644
--- a/tools/testtool/commands/test_submission_test.go
+++ b/tools/testtool/commands/test_submission_test.go
@@ -1,8 +1,12 @@
 package commands
 
 import (
+	"bufio"
 	"errors"
+	"fmt"
+	"io"
 	"io/ioutil"
+	"os"
 	"path"
 	"path/filepath"
 	"testing"
@@ -27,6 +31,35 @@ func listDirs(dir string) ([]string, error) {
 	return dirs, nil
 }
 
+func doTestSubmission(t *testing.T, studentRepo, privateRepo, problem string) error {
+	annotate := func(prefix string, f **os.File) func() {
+		pr, pw, err := os.Pipe()
+		require.NoError(t, err)
+
+		oldF := *f
+		*f = pw
+
+		go func() {
+			s := bufio.NewScanner(pr)
+			for s.Scan() {
+				io.WriteString(oldF, fmt.Sprintf("%s%s\n", prefix, s.Text()))
+			}
+		}()
+
+		return func() {
+			pw.Close()
+			*f = oldF
+		}
+	}
+
+	t.Logf("=== testing started ===")
+	defer annotate(">>> STDOUT >>>", &os.Stdout)()
+	defer annotate(">>> STDERR >>>", &os.Stderr)()
+	defer t.Logf("=== testing finished ===")
+
+	return testSubmission(studentRepo, privateRepo, problem)
+}
+
 func Test_testSubmission_correct(t *testing.T) {
 	testDirs, err := listDirs("../testdata/submissions/correct")
 	require.NoError(t, err)
@@ -39,7 +72,7 @@ func Test_testSubmission_correct(t *testing.T) {
 			studentRepo := path.Join(absDir, "student")
 			privateRepo := path.Join(absDir, "private")
 
-			require.NoError(t, testSubmission(studentRepo, privateRepo, problem))
+			require.NoError(t, doTestSubmission(t, studentRepo, privateRepo, problem))
 		})
 	}
 }
@@ -57,7 +90,7 @@ func Test_testSubmission_incorrect(t *testing.T) {
 			studentRepo := path.Join(absDir, "student")
 			privateRepo := path.Join(absDir, "private")
 
-			err := testSubmission(studentRepo, privateRepo, problem)
+			err := doTestSubmission(t, studentRepo, privateRepo, problem)
 			require.Error(t, err)
 
 			if problem == "brokentest" {