feat(devkit): add coverage trending helpers
Implement coverage profile and output parsing, snapshot comparison, and a JSON-backed coverage store. Co-Authored-By: Virgil <virgil@lethean.io>
This commit is contained in:
Virgil
parent
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commit
cbf650918a
2 changed files with 431 additions and 0 deletions
323
devkit/coverage.go
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323
devkit/coverage.go
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package devkit
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import (
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"encoding/json"
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"fmt"
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"os"
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"path"
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"path/filepath"
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"regexp"
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"sort"
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"strconv"
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"strings"
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"time"
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)
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// CoveragePackage describes coverage for a single package or directory.
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type CoveragePackage struct {
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Name string `json:"name"`
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CoveredStatements int `json:"covered_statements"`
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TotalStatements int `json:"total_statements"`
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Coverage float64 `json:"coverage"`
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}
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// CoverageSnapshot captures a point-in-time view of coverage across packages.
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type CoverageSnapshot struct {
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CapturedAt time.Time `json:"captured_at"`
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Packages []CoveragePackage `json:"packages"`
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Total CoveragePackage `json:"total"`
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}
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// CoverageDelta describes how a single package changed between snapshots.
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type CoverageDelta struct {
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Name string `json:"name"`
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Previous float64 `json:"previous"`
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Current float64 `json:"current"`
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Delta float64 `json:"delta"`
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}
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// CoverageComparison summarises the differences between two coverage snapshots.
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type CoverageComparison struct {
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Regressions []CoverageDelta `json:"regressions"`
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Improvements []CoverageDelta `json:"improvements"`
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NewPackages []CoveragePackage `json:"new_packages"`
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Removed []CoveragePackage `json:"removed"`
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TotalDelta float64 `json:"total_delta"`
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}
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// CoverageStore persists coverage snapshots to disk.
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type CoverageStore struct {
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path string
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}
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type coverageBucket struct {
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covered int
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total int
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}
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var coverProfileLineRE = regexp.MustCompile(`^(.+?):\d+\.\d+,\d+\.\d+\s+(\d+)\s+(\d+)$`)
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var coverOutputLineRE = regexp.MustCompile(`^(?:ok|\?)?\s*(\S+)\s+.*coverage:\s+([0-9]+(?:\.[0-9]+)?)% of statements$`)
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// NewCoverageStore creates a store backed by the given file path.
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func NewCoverageStore(path string) *CoverageStore {
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return &CoverageStore{path: path}
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}
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// Append stores a new snapshot, creating the parent directory if needed.
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func (s *CoverageStore) Append(snapshot CoverageSnapshot) error {
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if err := os.MkdirAll(filepath.Dir(s.path), 0o755); err != nil {
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return err
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}
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snapshots, err := s.Load()
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if err != nil {
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return err
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}
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snapshot.CapturedAt = snapshot.CapturedAt.UTC()
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snapshots = append(snapshots, snapshot)
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data, err := json.MarshalIndent(snapshots, "", " ")
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if err != nil {
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return err
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}
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return os.WriteFile(s.path, data, 0o600)
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}
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// Load reads all snapshots from disk.
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func (s *CoverageStore) Load() ([]CoverageSnapshot, error) {
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data, err := os.ReadFile(s.path)
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if err != nil {
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if os.IsNotExist(err) {
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return nil, nil
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}
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return nil, err
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}
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if len(strings.TrimSpace(string(data))) == 0 {
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return nil, nil
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}
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var snapshots []CoverageSnapshot
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if err := json.Unmarshal(data, &snapshots); err != nil {
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return nil, err
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}
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return snapshots, nil
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}
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// Latest returns the newest snapshot in the store.
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func (s *CoverageStore) Latest() (CoverageSnapshot, error) {
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snapshots, err := s.Load()
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if err != nil {
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return CoverageSnapshot{}, err
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}
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if len(snapshots) == 0 {
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return CoverageSnapshot{}, fmt.Errorf("coverage store is empty")
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}
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return snapshots[len(snapshots)-1], nil
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}
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// ParseCoverProfile parses go test -coverprofile output into a coverage snapshot.
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func ParseCoverProfile(data string) (CoverageSnapshot, error) {
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if strings.TrimSpace(data) == "" {
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return CoverageSnapshot{}, nil
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}
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packages := make(map[string]*coverageBucket)
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total := coverageBucket{}
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for _, rawLine := range strings.Split(strings.TrimSpace(data), "\n") {
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line := strings.TrimSpace(rawLine)
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if line == "" || strings.HasPrefix(line, "mode:") {
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continue
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}
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match := coverProfileLineRE.FindStringSubmatch(line)
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if match == nil {
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return CoverageSnapshot{}, fmt.Errorf("invalid cover profile line: %s", line)
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}
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file := filepath.ToSlash(match[1])
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stmts, err := strconv.Atoi(match[2])
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if err != nil {
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return CoverageSnapshot{}, err
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}
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count, err := strconv.Atoi(match[3])
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if err != nil {
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return CoverageSnapshot{}, err
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}
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dir := path.Dir(file)
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if dir == "" {
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dir = "."
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}
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b := packages[dir]
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if b == nil {
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b = &coverageBucket{}
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packages[dir] = b
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}
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b.total += stmts
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total.total += stmts
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if count > 0 {
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b.covered += stmts
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total.covered += stmts
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}
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}
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return snapshotFromBuckets(packages, total), nil
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}
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// ParseCoverOutput parses human-readable go test -cover output into a snapshot.
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func ParseCoverOutput(output string) (CoverageSnapshot, error) {
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if strings.TrimSpace(output) == "" {
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return CoverageSnapshot{}, nil
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}
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packages := make(map[string]*CoveragePackage)
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var total CoveragePackage
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for _, rawLine := range strings.Split(strings.TrimSpace(output), "\n") {
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line := strings.TrimSpace(rawLine)
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if line == "" {
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continue
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}
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match := coverOutputLineRE.FindStringSubmatch(line)
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if match == nil {
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continue
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}
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name := match[1]
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coverage, err := strconv.ParseFloat(match[2], 64)
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if err != nil {
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return CoverageSnapshot{}, err
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}
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pkg := &CoveragePackage{
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Name: name,
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Coverage: coverage,
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}
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packages[name] = pkg
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total.Coverage += coverage
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total.TotalStatements++
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}
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if len(packages) == 0 {
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return CoverageSnapshot{}, nil
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}
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snapshot := CoverageSnapshot{
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CapturedAt: time.Now().UTC(),
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Packages: make([]CoveragePackage, 0, len(packages)),
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}
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for _, pkg := range packages {
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snapshot.Packages = append(snapshot.Packages, *pkg)
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}
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sort.Slice(snapshot.Packages, func(i, j int) bool {
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return snapshot.Packages[i].Name < snapshot.Packages[j].Name
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})
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snapshot.Total.Name = "total"
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if total.TotalStatements > 0 {
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snapshot.Total.Coverage = total.Coverage / float64(total.TotalStatements)
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}
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return snapshot, nil
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}
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// CompareCoverage compares two snapshots and reports regressions and improvements.
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func CompareCoverage(previous, current CoverageSnapshot) CoverageComparison {
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prevPackages := coverageMap(previous.Packages)
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currPackages := coverageMap(current.Packages)
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comparison := CoverageComparison{
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NewPackages: make([]CoveragePackage, 0),
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Removed: make([]CoveragePackage, 0),
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}
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for name, curr := range currPackages {
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prev, ok := prevPackages[name]
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if !ok {
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comparison.NewPackages = append(comparison.NewPackages, curr)
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continue
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}
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delta := curr.Coverage - prev.Coverage
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change := CoverageDelta{
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Name: name,
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Previous: prev.Coverage,
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Current: curr.Coverage,
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Delta: delta,
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}
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if delta < 0 {
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comparison.Regressions = append(comparison.Regressions, change)
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} else if delta > 0 {
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comparison.Improvements = append(comparison.Improvements, change)
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}
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}
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for name, prev := range prevPackages {
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if _, ok := currPackages[name]; !ok {
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comparison.Removed = append(comparison.Removed, prev)
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}
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}
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sortCoverageComparison(&comparison)
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comparison.TotalDelta = current.Total.Coverage - previous.Total.Coverage
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return comparison
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}
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func snapshotFromBuckets(packages map[string]*coverageBucket, total coverageBucket) CoverageSnapshot {
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snapshot := CoverageSnapshot{
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CapturedAt: time.Now().UTC(),
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Packages: make([]CoveragePackage, 0, len(packages)),
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}
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for name, b := range packages {
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snapshot.Packages = append(snapshot.Packages, coverageAverage(name, b.covered, b.total))
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}
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sort.Slice(snapshot.Packages, func(i, j int) bool {
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return snapshot.Packages[i].Name < snapshot.Packages[j].Name
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})
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snapshot.Total = coverageAverage("total", total.covered, total.total)
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return snapshot
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}
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func coverageAverage(name string, covered, total int) CoveragePackage {
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pkg := CoveragePackage{
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Name: name,
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CoveredStatements: covered,
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TotalStatements: total,
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}
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if total > 0 {
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pkg.Coverage = float64(covered) / float64(total) * 100
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}
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return pkg
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}
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func coverageMap(packages []CoveragePackage) map[string]CoveragePackage {
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result := make(map[string]CoveragePackage, len(packages))
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for _, pkg := range packages {
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result[pkg.Name] = pkg
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}
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return result
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}
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func sortCoverageComparison(comparison *CoverageComparison) {
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sort.Slice(comparison.Regressions, func(i, j int) bool {
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return comparison.Regressions[i].Name < comparison.Regressions[j].Name
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})
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sort.Slice(comparison.Improvements, func(i, j int) bool {
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return comparison.Improvements[i].Name < comparison.Improvements[j].Name
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})
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sort.Slice(comparison.NewPackages, func(i, j int) bool {
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return comparison.NewPackages[i].Name < comparison.NewPackages[j].Name
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})
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sort.Slice(comparison.Removed, func(i, j int) bool {
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return comparison.Removed[i].Name < comparison.Removed[j].Name
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})
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}
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108
devkit/coverage_test.go
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108
devkit/coverage_test.go
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@ -0,0 +1,108 @@
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package devkit
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import (
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"os"
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"path/filepath"
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"testing"
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"time"
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"github.com/stretchr/testify/require"
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)
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func TestParseCoverProfile_Good(t *testing.T) {
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snapshot, err := ParseCoverProfile(`mode: set
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github.com/acme/project/foo/foo.go:1.1,3.1 2 1
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github.com/acme/project/foo/bar.go:1.1,4.1 3 0
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github.com/acme/project/baz/baz.go:1.1,2.1 4 4
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`)
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require.NoError(t, err)
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require.Len(t, snapshot.Packages, 2)
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require.Equal(t, "github.com/acme/project/baz", snapshot.Packages[0].Name)
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require.Equal(t, "github.com/acme/project/foo", snapshot.Packages[1].Name)
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require.InDelta(t, 100.0, snapshot.Packages[0].Coverage, 0.0001)
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require.InDelta(t, 40.0, snapshot.Packages[1].Coverage, 0.0001)
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require.InDelta(t, 66.6667, snapshot.Total.Coverage, 0.0001)
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}
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func TestParseCoverProfile_Bad(t *testing.T) {
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_, err := ParseCoverProfile("mode: set\nbroken line")
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require.Error(t, err)
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}
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func TestParseCoverOutput_Good(t *testing.T) {
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snapshot, err := ParseCoverOutput(`ok github.com/acme/project/foo 0.123s coverage: 75.0% of statements
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ok github.com/acme/project/bar 0.456s coverage: 50.0% of statements
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`)
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require.NoError(t, err)
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require.Len(t, snapshot.Packages, 2)
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require.Equal(t, "github.com/acme/project/bar", snapshot.Packages[0].Name)
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require.Equal(t, "github.com/acme/project/foo", snapshot.Packages[1].Name)
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require.InDelta(t, 62.5, snapshot.Total.Coverage, 0.0001)
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}
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func TestCompareCoverage_Good(t *testing.T) {
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previous := CoverageSnapshot{
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Packages: []CoveragePackage{
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{Name: "pkg/a", Coverage: 90.0},
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{Name: "pkg/b", Coverage: 80.0},
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},
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Total: CoveragePackage{Name: "total", Coverage: 85.0},
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}
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current := CoverageSnapshot{
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Packages: []CoveragePackage{
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{Name: "pkg/a", Coverage: 87.5},
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{Name: "pkg/b", Coverage: 82.0},
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{Name: "pkg/c", Coverage: 100.0},
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},
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Total: CoveragePackage{Name: "total", Coverage: 89.0},
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}
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comparison := CompareCoverage(previous, current)
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require.Len(t, comparison.Regressions, 1)
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require.Len(t, comparison.Improvements, 1)
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require.Len(t, comparison.NewPackages, 1)
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require.Empty(t, comparison.Removed)
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require.Equal(t, "pkg/a", comparison.Regressions[0].Name)
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require.Equal(t, "pkg/b", comparison.Improvements[0].Name)
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require.Equal(t, "pkg/c", comparison.NewPackages[0].Name)
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require.InDelta(t, 4.0, comparison.TotalDelta, 0.0001)
|
||||||
|
}
|
||||||
|
|
||||||
|
func TestCoverageStore_Good(t *testing.T) {
|
||||||
|
dir := t.TempDir()
|
||||||
|
store := NewCoverageStore(filepath.Join(dir, "coverage.json"))
|
||||||
|
|
||||||
|
first := CoverageSnapshot{
|
||||||
|
CapturedAt: time.Date(2026, 4, 1, 10, 0, 0, 0, time.UTC),
|
||||||
|
Packages: []CoveragePackage{{Name: "pkg/a", Coverage: 80.0}},
|
||||||
|
Total: CoveragePackage{Name: "total", Coverage: 80.0},
|
||||||
|
}
|
||||||
|
second := CoverageSnapshot{
|
||||||
|
CapturedAt: time.Date(2026, 4, 1, 11, 0, 0, 0, time.UTC),
|
||||||
|
Packages: []CoveragePackage{{Name: "pkg/a", Coverage: 82.5}},
|
||||||
|
Total: CoveragePackage{Name: "total", Coverage: 82.5},
|
||||||
|
}
|
||||||
|
|
||||||
|
require.NoError(t, store.Append(first))
|
||||||
|
require.NoError(t, store.Append(second))
|
||||||
|
|
||||||
|
snapshots, err := store.Load()
|
||||||
|
require.NoError(t, err)
|
||||||
|
require.Len(t, snapshots, 2)
|
||||||
|
require.Equal(t, first.CapturedAt, snapshots[0].CapturedAt)
|
||||||
|
require.Equal(t, second.CapturedAt, snapshots[1].CapturedAt)
|
||||||
|
|
||||||
|
latest, err := store.Latest()
|
||||||
|
require.NoError(t, err)
|
||||||
|
require.Equal(t, second.CapturedAt, latest.CapturedAt)
|
||||||
|
}
|
||||||
|
|
||||||
|
func TestCoverageStore_Bad(t *testing.T) {
|
||||||
|
dir := t.TempDir()
|
||||||
|
path := filepath.Join(dir, "coverage.json")
|
||||||
|
require.NoError(t, os.WriteFile(path, []byte("{"), 0o600))
|
||||||
|
|
||||||
|
store := NewCoverageStore(path)
|
||||||
|
_, err := store.Load()
|
||||||
|
require.Error(t, err)
|
||||||
|
}
|
||||||
Loading…
Add table
Reference in a new issue