Add coverpkg specification.

Currently, packages in coverme without tests created by student
are not checked for coverage, because no there are no test targets
for them at all!

The issue can be fixed by simply creating empty !change files,
but we are engineers, aren't we? :)

Bonus point: it prevents new packages from giving false coverage credit.
For example, mock file generated by gomock will have lots of covered code
almost instantly. However, the task can be hacked by adding new code to
existing packages.

coverme/app/coverage_test.go

@@ -2,4 +2,4 @@
 
 package app
 
-// min coverage: 90%
+// min coverage: app,client,models,utils 90%

tools/testtool/commands/coverage.go

@@ -20,6 +20,7 @@ const coverageCommentPrefix = "min coverage: "
 type CoverageRequirements struct {
 	Enabled  bool
 	Percent  float64
+	Packages []string
 }
 
 // getCoverageRequirements searches for comment in test files
@@ -58,14 +59,25 @@ func searchCoverageComment(fname string) (*CoverageRequirements, error) {
 		}
 		t = strings.TrimPrefix(t, coverageCommentPrefix)
 		t = strings.TrimSuffix(t, "%\n")
-		percent, err := strconv.ParseFloat(t, 64)
+
+		parts := strings.Split(t, " ")
+		if len(parts) != 2 {
+			continue
+		}
+
+		percent, err := strconv.ParseFloat(parts[1], 64)
 		if err != nil {
 			continue
 		}
 		if percent < 0 || percent > 100.0 {
 			continue
 		}
-		return &CoverageRequirements{Enabled: true, Percent: percent}, nil
+
+		return &CoverageRequirements{
+			Enabled:  true,
+			Percent:  percent,
+			Packages: strings.Split(parts[0], ","),
+		}, nil
 	}
 
 	return &CoverageRequirements{}, nil

tools/testtool/commands/coverage_test.go

@@ -10,4 +10,5 @@ func Test_getCoverageRequirements(t *testing.T) {
 	r := getCoverageRequirements("../testdata/coverage/sum")
 	require.True(t, r.Enabled)
 	require.Equal(t, 90.0, r.Percent)
+	require.Equal(t, []string{"."}, r.Packages)
 }

tools/testtool/commands/test_submission.go

@@ -254,7 +254,11 @@ func runTests(testDir, privateRepo, problem string) error {
 		testBinaries[testPkg] = binPath
 		cmd := []string{"test", "-mod", "readonly", "-tags", "private", "-c", "-o", binPath, testPkg}
 		if coverageReq.Enabled {
-			cmd = append(cmd, "-cover")
+			pkgs := make([]string, len(coverageReq.Packages))
+			for i, pkg := range coverageReq.Packages {
+				pkgs[i] = path.Join(moduleImportPath, problem, pkg)
+			}
+			cmd = append(cmd, "-cover", "-coverpkg", strings.Join(pkgs, ","))
 		}
 		if err := runGo(cmd...); err != nil {
 			return fmt.Errorf("error building test in %s: %w", testPkg, err)

tools/testtool/testdata/coverage/sum/subpkg/empty_test.go

@@ -3,20 +3,22 @@ package subpkg
 
 // Incorrect coverage comments:
 
-// min coverage: -1%
+// min coverage: . -1%
 
-// min coverage: 100.001%
+// min coverage: . 100.001%
 
-// min coverage: 100 %
+// min coverage: . 100 %
 
-// min coverage:10%
+// min coverage:. 10%
 
-//  min coverage: 19%
+//  min coverage: . 19%
-
-// Correct coverage comment:
 
 // min coverage: 90%
 
+// Correct coverage comment:
+
+// min coverage: . 90%
+
 // Testtool uses first matching comment.
 
-// min coverage: 91%
+// min coverage: . 91%

tools/testtool/testdata/submissions/correct/coverme/private/coverme/coverage_test.go

@@ -10,7 +10,7 @@ import (
 	"gitlab.com/slon/shad-go/coverme"
 )
 
-// min coverage: 70%
+// min coverage: .,subpkg 70%
 
 func TestSum(t *testing.T) {
 	require.Equal(t, int64(2), coverme.Sum(1, 1))

tools/testtool/testdata/submissions/correct/coverme/student/coverme/coverage_test.go

@@ -10,7 +10,7 @@ import (
 	"gitlab.com/slon/shad-go/coverme"
 )
 
-// min coverage: 70%
+// min coverage: .,subpkg 70%
 
 func TestSum(t *testing.T) {
 	require.Equal(t, int64(2), coverme.Sum(1, 1))

tools/testtool/testdata/submissions/incorrect/poorcoverage/private/poorcoverage/coverage_test.go

@@ -9,7 +9,7 @@ import (
 	"gitlab.com/slon/shad-go/poorcoverage"
 )
 
-// min coverage: 100%
+// min coverage: . 100%
 
 func TestSum(t *testing.T) {
 	require.Equal(t, int64(2), poorcoverage.Sum(1, 1))

tools/testtool/testdata/submissions/incorrect/poorcoverage/student/poorcoverage/coverage_test.go

@@ -9,7 +9,7 @@ import (
 	"gitlab.com/slon/shad-go/poorcoverage"
 )
 
-// min coverage: 100%
+// min coverage: . 100%
 
 func TestSum(t *testing.T) {
 	require.Equal(t, int64(2), poorcoverage.Sum(1, 1))