Identify and, filter or display coverage output

Identify coverage output events with string comparison. There does not
appear to be any way.

Add coverage output to the short format, and filter out the duplicate
line from the standard-quiet output.

go.sum

@@ -57,3 +57,4 @@ gopkg.in/yaml.v2 v2.2.1 h1:mUhvW9EsL+naU5Q3cakzfE91YhliOondGd6ZrsDBHQE=
 gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gotest.tools v2.1.0+incompatible h1:5USw7CrJBYKqjg9R7QlA6jzqZKEAtvW82aNmsxxGPxw=
 gotest.tools v2.1.0+incompatible/go.mod h1:DsYFclhRJ6vuDpmuTbkuFWG+y2sxOXAzmJt81HFBacw=
+gotest.tools v2.2.0+incompatible h1:VsBPFP1AI068pPrMxtb/S8Zkgf9xEmTLJjfM+P5UIEo=

testjson/execution.go

@@ -69,6 +69,9 @@ type Package struct {
 	Skipped []TestCase
 	Passed  []TestCase
 	output  map[string][]string
+	// coverage stores the code coverage output for the package without the
+	// trailing newline (ex: coverage: 91.1% of statements).
+	coverage string
 	// action identifies if the package passed or failed. A package may fail
 	// with no test failures if an init() or TestMain exits non-zero.
 	// skip indicates there were no tests.
@@ -135,6 +138,9 @@ func (e *Execution) add(event TestEvent) {
 		case ActionPass, ActionFail:
 			pkg.action = event.Action
 		case ActionOutput:
+			if isCoverageOutput(event.Output) {
+				pkg.coverage = strings.TrimRight(event.Output, "\n")
+			}
 			pkg.output[""] = append(pkg.output[""], event.Output)
 		}
 		return
@@ -173,6 +179,12 @@ func elapsedDuration(elapsed float64) time.Duration {
 	return time.Duration(elapsed*1000) * time.Millisecond
 }
 
+func isCoverageOutput(output string) bool {
+	return all(
+		strings.HasPrefix(output, "coverage:"),
+		strings.HasSuffix(output, "% of statements\n"))
+}
+
 // Output returns the full test output for a test.
 func (e *Execution) Output(pkg, test string) string {
 	return strings.Join(e.packages[pkg].output[test], "")

testjson/format.go

@@ -31,7 +31,10 @@ func standardVerboseFormat(event TestEvent, _ *Execution) (string, error) {
 
 // go test
 func standardQuietFormat(event TestEvent, _ *Execution) (string, error) {
-	if event.PackageEvent() && event.Output != "PASS\n" {
+	if !event.PackageEvent() {
+		return "", nil
+	}
+	if event.Output != "PASS\n" && !isCoverageOutput(event.Output) {
 		return event.Output, nil
 	}
 	return "", nil
@@ -96,7 +99,7 @@ func all(cond ...bool) bool {
 	return true
 }
 
-func shortFormat(event TestEvent, _ *Execution) (string, error) {
+func shortFormat(event TestEvent, exec *Execution) (string, error) {
 	if !event.PackageEvent() {
 		return "", nil
 	}
@@ -107,9 +110,20 @@ func shortFormat(event TestEvent, _ *Execution) (string, error) {
 		}
 		return fmt.Sprintf(" (%s)", d)
 	}
+	fmtCoverage := func() string {
+		pkg := exec.Package(event.Package)
+		if pkg.coverage == "" {
+			return ""
+		}
+		return "     (" + pkg.coverage + ")"
+	}
 	fmtEvent := func(action string) (string, error) {
-		return fmt.Sprintf("%s  %s%s\n",
-			action, relativePackagePath(event.Package), fmtElapsed()), nil
+		return fmt.Sprintf("%s  %s%s%s\n",
+			action,
+			relativePackagePath(event.Package),
+			fmtElapsed(),
+			fmtCoverage(),
+		), nil
 	}
 	withColor := colorEvent(event)
 	switch event.Action {