initial effort

Author: vladopajic

pkg/testcoverage/check.go

@@ -105,6 +105,7 @@ func Analyze(cfg Config, current, base []coverage.Stats) AnalyzeResult {
 
 	return AnalyzeResult{
 		Threshold:           thr,
+		DiffThreshold:       cfg.Diff.Threshold,
 		HasFileOverrides:    hasFileOverrides,
 		HasPackageOverrides: hasPackageOverrides,
 		FilesBelowThreshold: checkCoverageStatsBelowThreshold(current, thr.File, overrideRules),
@@ -115,6 +116,7 @@ func Analyze(cfg Config, current, base []coverage.Stats) AnalyzeResult {
 		TotalStats:              coverage.StatsCalcTotal(current),
 		HasBaseBreakdown:        len(base) > 0,
 		Diff:                    calculateStatsDiff(current, base),
+		DiffPercentage:          TotalPercentageDiff(current, base),
 	}
 }
 

pkg/testcoverage/config.go

@@ -53,7 +53,8 @@ type Exclude struct {
 }
 
 type Diff struct {
-	BaseBreakdownFileName string `yaml:"base-breakdown-file-name"`
+	BaseBreakdownFileName string   `yaml:"base-breakdown-file-name"`
+	Threshold             *float64 `yaml:"threshold"`
 }
 
 type Badge struct {

pkg/testcoverage/config_test.go

@@ -240,6 +240,7 @@ func nonZeroConfig() Config {
 		BreakdownFileName: "breakdown.testcoverage",
 		Diff: Diff{
 			BaseBreakdownFileName: "breakdown.testcoverage",
+			Threshold:             ptr(-1.1),
 		},
 		GithubActionOutput: true,
 	}
@@ -261,7 +262,8 @@ exclude:
     - path2
 breakdown-file-name: 'breakdown.testcoverage'
 diff:
-  base-breakdown-file-name: 'breakdown.testcoverage'	
+  base-breakdown-file-name: 'breakdown.testcoverage'
+  threshold: -1.1	
 github-action-output: true`
 }
 

pkg/testcoverage/helpers_test.go

@@ -14,6 +14,10 @@ import (
 	"github.com/vladopajic/go-test-coverage/v2/pkg/testcoverage/coverage"
 )
 
+func ptr[T any](t T) *T {
+	return &t
+}
+
 func mergeStats(a, b []coverage.Stats) []coverage.Stats {
 	r := make([]coverage.Stats, 0, len(a)+len(b))
 	r = append(r, a...)

pkg/testcoverage/report.go

@@ -27,14 +27,6 @@ func reportCoverage(w io.Writer, result AnalyzeResult) {
 	tabber := tabwriter.NewWriter(w, 1, 8, 2, '\t', 0) //nolint:mnd // relax
 	defer tabber.Flush()
 
-	statusStr := func(passing bool) string {
-		if passing {
-			return "PASS"
-		}
-
-		return "FAIL"
-	}
-
 	thr := result.Threshold
 
 	if thr.File > 0 || result.HasFileOverrides { // File threshold report
@@ -103,13 +95,19 @@ func reportDiff(w io.Writer, result AnalyzeResult) {
 	tabber := tabwriter.NewWriter(w, 1, 8, 2, '\t', 0) //nolint:mnd // relax
 	defer tabber.Flush()
 
+	if result.DiffThreshold != nil {
+		status := statusStr(result.MeetsDiffThreshold())
+		fmt.Fprintf(tabber, "\nCoverage difference threshold (%.2f%%) satisfied:\t %s", *result.DiffThreshold, status)
+		fmt.Fprintf(tabber, "\nCoverage difference: %.2f%%\n", result.DiffPercentage)
+	}
+
 	if len(result.Diff) == 0 {
-		fmt.Fprintf(tabber, "\nCurrent tests coverage has not changed.\n")
+		fmt.Fprintf(tabber, "\nNo coverage changes in any files compared to the base.\n")
 		return
 	}
 
-	td := TotalLinesDiff(result.Diff)
-	fmt.Fprintf(tabber, "\nCurrent tests coverage has changed with %d lines missing coverage.", td)
+	td := TotalLinesMissingCoverage(result.Diff)
+	fmt.Fprintf(tabber, "\nTest coverage has changed in the current files, with %d lines missing coverage.", td)
 	fmt.Fprintf(tabber, "\n  file:\tuncovered:\tcurrent coverage:\tbase coverage:")
 
 	for _, d := range result.Diff {
@@ -242,3 +240,11 @@ func compressUncoveredLines(w io.Writer, ull []int) {
 		printRange(last, ull[len(ull)-1])
 	}
 }
+
+func statusStr(passing bool) string {
+	if passing {
+		return "PASS"
+	}
+
+	return "FAIL"
+}

pkg/testcoverage/types.go

@@ -10,20 +10,31 @@ import (
 
 type AnalyzeResult struct {
 	Threshold               Threshold
+	DiffThreshold           *float64
 	FilesBelowThreshold     []coverage.Stats
 	PackagesBelowThreshold  []coverage.Stats
 	FilesWithUncoveredLines []coverage.Stats
 	TotalStats              coverage.Stats
 	HasBaseBreakdown        bool
 	Diff                    []FileCoverageDiff
+	DiffPercentage          float64
 	HasFileOverrides        bool
 	HasPackageOverrides     bool
 }
 
 func (r *AnalyzeResult) Pass() bool {
 	return r.MeetsTotalCoverage() &&
 		len(r.FilesBelowThreshold) == 0 &&
-		len(r.PackagesBelowThreshold) == 0
+		len(r.PackagesBelowThreshold) == 0 &&
+		r.MeetsDiffThreshold()
+}
+
+func (r *AnalyzeResult) MeetsDiffThreshold() bool {
+	if r.DiffThreshold == nil || !r.HasBaseBreakdown {
+		return true
+	}
+
+	return *r.DiffThreshold <= r.DiffPercentage
 }
 
 func (r *AnalyzeResult) MeetsTotalCoverage() bool {
@@ -109,11 +120,21 @@ func calculateStatsDiff(current, base []coverage.Stats) []FileCoverageDiff {
 	return res
 }
 
-func TotalLinesDiff(diff []FileCoverageDiff) int {
+func TotalLinesMissingCoverage(diff []FileCoverageDiff) int {
 	r := 0
 	for _, d := range diff {
 		r += d.Current.UncoveredLinesCount()
 	}
 
 	return r
 }
+
+func TotalPercentageDiff(current, base []coverage.Stats) float64 {
+	curretStats := coverage.StatsCalcTotal(current)
+	baseStats := coverage.StatsCalcTotal(base)
+
+	cp := curretStats.CoveredPercentageF()
+	bp := baseStats.CoveredPercentageF()
+
+	return cp - bp
+}