first commit

go.mod

@@ -0,0 +1,3 @@
+module code.wmdillon.com/wmdillon/gotestprofile
+
+go 1.25.3

main.go

@@ -0,0 +1,107 @@
+package main
+
+import (
+	"bytes"
+	"errors"
+	"flag"
+	"fmt"
+	"log"
+	"os"
+	"os/exec"
+	"strings"
+	"time"
+)
+
+var (
+	BaseOutputFilename string
+)
+
+func ProfileOutputFilename() string {
+	return fmt.Sprintf("%s.profile", BaseOutputFilename)
+}
+
+func HTMLOutputFilename() string {
+	return fmt.Sprintf("%s.html", ProfileOutputFilename())
+}
+
+func GenerateGoTestArgs() []string {
+	return []string{
+		"test", // run the test command in go
+		fmt.Sprintf("-coverprofile=%s", ProfileOutputFilename()), // generate a coverprofile with the given output name
+		"./...", // on any and all go modules here, recursively
+	}
+}
+
+func GenerateGoToolCoverArgs() []string {
+	return []string{
+		"tool",
+		"cover", // go tool cover
+		fmt.Sprintf("-html=%s", ProfileOutputFilename()),
+		"-o",
+		HTMLOutputFilename(),
+	}
+}
+
+func GenerateCoverageReport() (string, error) {
+	cmd := exec.Command("go", GenerateGoTestArgs()...)
+	output, err := cmd.CombinedOutput()
+	output = bytes.TrimSpace(output)
+	if err != nil {
+		return "", fmt.Errorf("error generating the coverage profile: %w\n%s", err, output)
+	}
+	return string(output), nil
+}
+
+func GenerateHTMLOutput() (string, error) {
+	cmd := exec.Command("go", GenerateGoToolCoverArgs()...)
+	output, err := cmd.CombinedOutput()
+	output = bytes.TrimSpace(output)
+	if err != nil {
+		return "", fmt.Errorf("error generating the html output: %w\n%s", err, output)
+	}
+	return string(output), nil
+}
+
+func Clean() error {
+	errs := make([]error, 0, 2)
+	profileOutputFilename := ProfileOutputFilename()
+	htmlOutputFilename := HTMLOutputFilename()
+	if err := os.Remove(profileOutputFilename); err != nil && !errors.Is(err, os.ErrNotExist) {
+		errs = append(errs, fmt.Errorf("error deleting %s: %w", profileOutputFilename, err))
+	}
+	if err := os.Remove(htmlOutputFilename); err != nil && !errors.Is(err, os.ErrNotExist) {
+		errs = append(errs, fmt.Errorf("error deleting %s: %w", htmlOutputFilename, err))
+	}
+	return errors.Join(errs...)
+}
+
+func main() {
+	programStart := time.Now()
+	log.SetFlags(0)
+
+	flag.StringVar(&BaseOutputFilename, "o", "testcoverage", "base filename used for output files (testcoverage.profile, testcoverage.html, etc)")
+	flag.Parse()
+	if args := flag.Args(); len(args) == 1 {
+		if strings.EqualFold(args[0], "clean") {
+			if err := Clean(); err != nil {
+				log.Fatalf("error cleaning: %v\n", err)
+			}
+			log.Printf("finished cleaning after %v\n", time.Since(programStart))
+			return
+		}
+	}
+
+	if _, err := GenerateCoverageReport(); err != nil {
+		log.Fatalf("%v; cannot proceed\n", err)
+	}
+	placeholderTime := time.Now()
+	log.Printf("wrote %s after %v\n", ProfileOutputFilename(), placeholderTime.Sub(programStart))
+
+	if _, err := GenerateHTMLOutput(); err != nil {
+		log.Fatalf("%v; cannot proceed\n", err)
+	}
+	finishedTime := time.Now()
+	log.Printf("wrote %s after %v\n", HTMLOutputFilename(), finishedTime.Sub(placeholderTime))
+
+	log.Printf("finished generating report after %v\n", time.Since(programStart))
+}