submit: Fix outdated PR templates with lower-case names (#371)

We use the contents of possible PR template sites
as the hash key for caching the PR templates we get from the remote.
This was only looking at `PULL_REQUEST_TEMPLATE.md` names,
even though `pull_request_template.md` is valid and accepted.

This change ensures that lower-cased versions are also considered
when calculating the hash key.

To do this, we consider upper-case and lower-case variants
of configured Forge template paths when calculating the cache key.
Case-insensitivity of this path is considered part of the Forge contract
because GitHub and GitLab both treat these as case-insensitive-ish.
We can adjust this assumption if we add a forge that doesn't.

Resolves #369

.changes/unreleased/Fixed-20240829-204353.yaml

@@ -0,0 +1,3 @@
+kind: Fixed
+body: 'github: Fix outdated PR templates being used when templates used lower-cased file names.'
+time: 2024-08-29T20:43:53.225092-07:00

internal/forge/shamhub/template.go

@@ -46,8 +46,15 @@ func (sh *ShamHub) handleChangeTemplate(w http.ResponseWriter, r *http.Request)
 	logw, flush := ioutil.LogWriter(sh.log, log.DebugLevel)
 	defer flush()
 
+	templatePaths := make(map[string]struct{})
+	for _, p := range _changeTemplatePaths {
+		templatePaths[p] = struct{}{}
+		templatePaths[strings.ToLower(p)] = struct{}{}
+		templatePaths[strings.ToUpper(p)] = struct{}{}
+	}
+
 	var res changeTemplateResponse
-	for _, path := range _changeTemplatePaths {
+	for path := range templatePaths {
 		cmd := exec.Command(sh.gitExe, "cat-file", "-p", "HEAD:"+path)
 		cmd.Dir = sh.repoDir(owner, repo)
 		cmd.Stderr = logw

internal/spice/template.go

@@ -5,7 +5,10 @@ import (
 	"crypto/sha256"
 	"errors"
 	"fmt"
-	"sort"
+	"maps"
+	"path"
+	"slices"
+	"strings"
 
 	"go.abhg.dev/gs/internal/forge"
 	"go.abhg.dev/gs/internal/git"
@@ -20,8 +23,17 @@ func (s *Service) ListChangeTemplates(
 	fr forge.Repository,
 ) ([]*forge.ChangeTemplate, error) {
 	// TODO: Should Repo be injected?
-	templatePaths := fr.Forge().ChangeTemplatePaths()
-	sort.Strings(templatePaths)
+	pathSet := make(map[string]struct{})
+	for _, p := range fr.Forge().ChangeTemplatePaths() {
+		pathSet[p] = struct{}{}
+
+		// Template paths are case-insensitive,
+		// so we'll also want to check other variants:
+		dir, file := path.Split(p)
+		pathSet[path.Join(dir, strings.ToLower(file))] = struct{}{}
+		pathSet[path.Join(dir, strings.ToUpper(file))] = struct{}{}
+	}
+	templatePaths := slices.Sorted(maps.Keys(pathSet))
 
 	// Cache key is a SHA256 hash of the following, in order:
 	//   - Number of allowed template paths

testdata/script/issue369_branch_submit_pr_template_cache_case_insensitive.txt

@@ -0,0 +1,88 @@
+# 'branch submit' invalidates template cache when a template is changed,
+# and it has a lower-cased name.
+#
+# https://github.com/abhinav/git-spice/issues/369
+
+as 'Test <[email protected]>'
+at '2024-08-29T20:21:22Z'
+
+# setup
+cd repo
+git init
+git add .shamhub
+git commit -m 'Initial commit'
+
+# set up a fake remote
+shamhub init
+shamhub new origin alice/example.git
+shamhub register alice
+git push origin main
+
+env SHAMHUB_USERNAME=alice
+gs auth login
+
+# Submit a PR with the first template.
+git add feature1.txt
+gs bc -m feature1
+gs branch submit --fill
+
+# Push a new template
+gs trunk
+mv $WORK/extra/change_template.md .shamhub/change_template.md
+git add .shamhub/change_template.md
+git commit -m 'Change the template'
+git push origin main
+
+# Create a new PR with the new template.
+git add feature2.txt
+gs bc -m feature2
+gs branch submit --fill
+
+shamhub dump changes
+cmpenv stdout $WORK/golden/pulls.json
+
+-- repo/.shamhub/change_template.md --
+This is the first template.
+
+-- extra/change_template.md --
+This is the second template.
+
+-- repo/feature1.txt --
+feature 1
+
+-- repo/feature2.txt --
+feature 2
+
+-- golden/pulls.json --
+[
+  {
+    "number": 1,
+    "html_url": "$SHAMHUB_URL/alice/example/change/1",
+    "state": "open",
+    "title": "feature1",
+    "body": "\n\nThis is the first template.\n",
+    "base": {
+      "ref": "main",
+      "sha": "2036762c8e15b28b80f94f5085db6d4d1f2678e8"
+    },
+    "head": {
+      "ref": "feature1",
+      "sha": "56594727085e14b4c394420451042c322eaf9441"
+    }
+  },
+  {
+    "number": 2,
+    "html_url": "$SHAMHUB_URL/alice/example/change/2",
+    "state": "open",
+    "title": "feature2",
+    "body": "\n\nThis is the second template.\n",
+    "base": {
+      "ref": "main",
+      "sha": "2036762c8e15b28b80f94f5085db6d4d1f2678e8"
+    },
+    "head": {
+      "ref": "feature2",
+      "sha": "91537b46b0c34e9df135cebe1e9270d5d7627952"
+    }
+  }
+]