Test the commit message wrapping boundaries

Hook regression tests distinguish a next word that does not fit within
72 columns from a genuinely underfilled paragraph. The checks include
trailers and formatted blocks, so the complete message is tested without
applying source-comment formatting to commit prose.

Issue: 3cdc678

diff --git a/.githooks/commit-msg-test b/.githooks/commit-msg-test
new file mode 100755 (executable)
index 0000000..d7499ae
--- /dev/null
+++ b/.githooks/commit-msg-test
@@ -0,0 +1,99 @@
+#!/usr/bin/env bash
+# Checks commit prose and trailers with the commit message hook.
+set -euo pipefail
+cd "$(dirname "$0")/.."
+
+work=$(mktemp -d)
+trap 'rm -rf "$work"' EXIT
+
+accept() {
+  cat > "$work/message"
+  if ! sh .githooks/commit-msg "$work/message" > "$work/output" 2>&1; then
+    printf 'commit-msg-test: valid message rejected\n' >&2
+    cat "$work/output" >&2
+    exit 1
+  fi
+}
+
+reject() {
+  cat > "$work/message"
+  if sh .githooks/commit-msg "$work/message" > "$work/output" 2>&1; then
+    printf 'commit-msg-test: invalid message accepted\n' >&2
+    cat "$work/message" >&2
+    exit 1
+  fi
+  grep -q "$1" "$work/output"
+}
+
+# The next word has 13 characters. Its preceding line has 60, so the
+# combined line has 74 characters and cannot fit the 72-column limit.
+accept <<'MESSAGE'
+Reflow comments and expand event literals
+
+Comment paragraphs use the repository reflow tool, and event literals
+put each field on its own line. The Telegram request comment
+distinguishes method-bearing setup errors from safe network causes. Code
+behavior and error values stay unchanged.
+
+Issue: 3cdc678
+MESSAGE
+
+reject 'unnecessary line break after line 3' <<'MESSAGE'
+Reflow comments and expand event literals
+
+Comment paragraphs use the repository reflow tool, and event
+literals put each field on its own line. The Telegram request comment
+distinguishes method-bearing setup errors from safe network causes. Code
+behavior and error values stay unchanged.
+
+Issue: 3cdc678
+MESSAGE
+
+accept <<'MESSAGE'
+Check a filled paragraph
+
+The paragraph fills each line before the next word starts another line.
+Its next word does not fit the line before it.
+
+Issue: abc1234
+MESSAGE
+
+reject 'longer than 72 characters' <<'MESSAGE'
+Reject a wide paragraph
+
+This paragraph has more than seventy-two characters because this extra word extends it.
+
+Issue: abc1234
+MESSAGE
+
+reject 'unnecessary line break after line 3' <<'MESSAGE'
+Reject a short paragraph line
+
+This line can hold
+the next word.
+
+Issue: abc1234
+MESSAGE
+
+accept <<'MESSAGE'
+Keep trailer lines separate
+
+The message has a body.
+
+Issue: abc1234
+Parent: def5678
+MESSAGE
+
+accept <<'MESSAGE'
+Keep formatted blocks separate
+
+- First list item
+- Second list item
+
+    first example line
+    second example line
+
+Issue: abc1234
+MESSAGE
+
+printf 'commit-msg-test: all cases pass\n'

diff --git a/bin/check b/bin/check
index e8e6e97ab96350c2812da6853c9d5ee82152188b..1b608bbe71afc3da8ce1efa45c5134243054e9d8 100755 (executable)
--- a/bin/check
+++ b/bin/check
@@ -28,4 +28,5 @@ go test -race -short ./...
 files '*.nix' | xargs nixfmt --check
 files '*.rst' | xargs rstfmt --check
 files '*.md' | xargs mdformat --check
 files '*.nix' | xargs nixfmt --check
 files '*.rst' | xargs rstfmt --check
 files '*.md' | xargs mdformat --check

-shellcheck bin/check bin/format bin/reflow bin/service-update .githooks/commit-msg
+bash .githooks/commit-msg-test
+shellcheck bin/check bin/format bin/reflow bin/service-update .githooks/commit-msg .githooks/commit-msg-test