Remove the "go report: A" badge from the README header, a shields.io static badge whose grade was written into its URL (#51)

CHANGELOG.md

@@ -227,6 +227,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   no cached database the command no longer tries to download one from GitHub
   first. The exit code is still 2.
 
+- **The README showed a `go report: A` badge that nothing measured.** It was a
+  shields.io static badge, which draws the value written into its URL, and it
+  linked to a goreportcard.com report. The goreportcard.com badge for the
+  module read `go report: retired` on 2026-10-17. The badge is removed.
+
 ## [1.3.1] - 2026-10-17
 
 ### Fixed

README.md

@@ -5,7 +5,6 @@
 Find the cryptography your dependencies bring in, see which of it quantum computers will break, and tell apart what your code actually calls from what is merely available to it.
 
 [![CI](https://github.com/csnp/qramm-cryptodeps/actions/workflows/ci.yml/badge.svg)](https://github.com/csnp/qramm-cryptodeps/actions/workflows/ci.yml)
-[![Go Report Card](https://img.shields.io/badge/go%20report-A-brightgreen)](https://goreportcard.com/report/github.com/csnp/qramm-cryptodeps)
 [![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](LICENSE)
 [![Go Version](https://img.shields.io/github/go-mod/go-version/csnp/qramm-cryptodeps)](go.mod)
 

cmd/cryptodeps/docs_badges_test.go

@@ -0,0 +1,128 @@
+// Copyright 2025-2026 CyberSecurity NonProfit (CSNP)
+// SPDX-License-Identifier: Apache-2.0
+
+package main
+
+import (
+	"net/url"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"testing"
+)
+
+// readmeBadge matches a linked badge image, [![alt](image)](link).
+var readmeBadge = regexp.MustCompile(`\[!\[([^\]]*)\]\(([^)\s]+)\)\]\(([^)\s]+)\)`)
+
+// staticBadgeMessage returns the value a shields.io static badge draws, and
+// false for any other image. A static badge draws the value written into its
+// URL, as /badge/<label>-<value>-<color> or /static/v1?message=<value>, so
+// nothing measures it. The /badge/dynamic/json, yaml, xml and toml forms draw
+// a value read from the document their url parameter names.
+func staticBadgeMessage(image string) (string, bool) {
+	u, err := url.Parse(image)
+	if err != nil || u.Host != "img.shields.io" {
+		return "", false
+	}
+	if u.Path == "/static/v1" {
+		return u.Query().Get("message"), true
+	}
+	content, ok := strings.CutPrefix(u.Path, "/badge/")
+	if !ok || strings.HasPrefix(content, "dynamic/") {
+		return "", false
+	}
+	// "--" is a literal dash and "__" a literal underscore; a single "_" is a space.
+	content = strings.NewReplacer("--", "\x00", "__", "\x01", "_", " ").Replace(content)
+	parts := strings.Split(content, "-")
+	message := parts[0]
+	if len(parts) > 2 {
+		message = parts[len(parts)-2]
+	}
+	return strings.NewReplacer("\x00", "-", "\x01", "_").Replace(message), true
+}
+
+// TestStaticBadgeMessage checks staticBadgeMessage on badge URLs. Each one
+// marked static drew the value given here when fetched from shields.io on
+// 2026-10-17, and the /badge/dynamic/json one drew the default branch it read
+// from the GitHub API.
+func TestStaticBadgeMessage(t *testing.T) {
+	for _, c := range []struct {
+		image   string
+		message string
+		static  bool
+	}{
+		{"https://img.shields.io/badge/go%20report-A-brightgreen", "A", true},
+		{"https://img.shields.io/badge/License-Apache%202.0-blue.svg", "Apache 2.0", true},
+		{"https://img.shields.io/badge/a--b-c__d_e-blue", "c_d e", true},
+		{"https://img.shields.io/badge/just%20message-blue", "just message", true},
+		{"https://img.shields.io/static/v1?label=go%20report&message=Z&color=blue", "Z", true},
+		{"https://img.shields.io/badge/dynamic/json?url=https%3A%2F%2Fapi.github.com%2Frepos%2Fcsnp%2Fcryptodeps&query=%24.default_branch&label=branch", "", false},
+		{"https://img.shields.io/github/go-mod/go-version/csnp/qramm-cryptodeps", "", false},
+		{"https://github.com/csnp/qramm-cryptodeps/actions/workflows/ci.yml/badge.svg", "", false},
+	} {
+		message, static := staticBadgeMessage(c.image)
+		if message != c.message || static != c.static {
+			t.Errorf("staticBadgeMessage(%s) = %q, %v; want %q, %v", c.image, message, static, c.message, c.static)
+		}
+	}
+}
+
+// repoFileHolds reports whether link names a file in the repository whose
+// text contains every word of value, ignoring case.
+func repoFileHolds(link, value string) bool {
+	u, err := url.Parse(link)
+	if err != nil || u.Scheme != "" || u.Host != "" || u.Path == "" {
+		return false
+	}
+	b, err := os.ReadFile(filepath.Join(repoRoot, filepath.FromSlash(u.Path)))
+	if err != nil {
+		return false
+	}
+	text := strings.ToLower(string(b))
+	for _, word := range strings.Fields(strings.ToLower(value)) {
+		if !strings.Contains(text, word) {
+			return false
+		}
+	}
+	return true
+}
+
+// TestDocsReadmeBadgesTakeTheirValuesFromASource covers a "go report: A"
+// badge in the README header. It was a shields.io static badge, so the grade
+// was typed into its URL and not measured, and it linked to goreportcard.com,
+// whose own badge for the module read "go report: retired" on 2026-10-17.
+//
+// A static badge passes only when it links to a file in the repository that
+// holds its value, as the License badge links to LICENSE. Other badges, such
+// as the CI workflow badge and the shields.io badge that reads go.mod, are not
+// checked: the test does not reach the network, so it cannot see the value a
+// service returns. A badge inside a fenced code block is an example, not one
+// of the README's badges, and is skipped.
+func TestDocsReadmeBadgesTakeTheirValuesFromASource(t *testing.T) {
+	const file = "README.md"
+	found := 0
+	inFence := false
+	for i, line := range strings.Split(readRepoFile(t, file), "\n") {
+		if strings.HasPrefix(line, "```") {
+			inFence = !inFence
+		}
+		if inFence {
+			continue
+		}
+		for _, m := range readmeBadge.FindAllStringSubmatch(line, -1) {
+			found++
+			alt, image, link := m[1], m[2], m[3]
+			message, static := staticBadgeMessage(image)
+			if !static || repoFileHolds(link, message) {
+				continue
+			}
+			t.Errorf("%s:%d: the %q badge shows %q, written into its URL %s, and links to %s, "+
+				"not to a file in the repository that holds that value. Use a badge that reads "+
+				"its value from a service, or remove it", file, i+1, alt, message, image, link)
+		}
+	}
+	if found == 0 {
+		t.Fatalf("%s has no badges; the badge pattern no longer matches them", file)
+	}
+}