fix!: detect missing blank line separator in body check

README.md

@@ -75,7 +75,7 @@ Available checks:
 * `subject` - Format matches `type(scope): description`, valid type,
     lowercase start, no trailing period, max 72 chars
 * `imperative` - First word is an imperative verb (for example `add` not `added`)
-* `body` - Body is present after a blank line
+* `body` - Blank line separates subject from body, and body is non-empty
 * `signed-off` - `Signed-off-by:` trailer exists
 * `signature` - Verify GPG or SSH signature
 

docs/index.html

@@ -369,7 +369,7 @@ <h3>Checks</h3>
               </tr>
               <tr>
                 <td><code>body</code></td>
-                <td>Body is present after a blank line</td>
+                <td>Blank line separates subject from body, and body is non-empty</td>
               </tr>
               <tr>
                 <td><code>signed-off</code></td>

src/git_commit_guard/__init__.py

@@ -220,11 +220,15 @@ def check_imperative(desc, result):
 
 
 def check_body(lines, result):
-    if len(lines) < 3:  # noqa: PLR2004
+    if len(lines) == 1:
         result.error("missing body", check=Check.BODY)
         return
     if lines[1].strip():
         result.error("missing blank line between subject and body", check=Check.BODY)
+        return
+    if len(lines) == 2:  # noqa: PLR2004 Magic value used in comparison, consider replacing 2 with a constant variable
+        result.error("missing body", check=Check.BODY)
+        return
     body_lines = [ln for ln in lines[2:] if not _TRAILER_RE.match(ln)]
     if not any(ln.strip() for ln in body_lines):
         result.error("missing body", check=Check.BODY)

tests/test_git_commit_guard.py

@@ -237,6 +237,12 @@ def test_missing_blank_line(self):
         check_body(["fix: add thing", "body text", "more"], r)
         assert not r.ok
 
+    def test_missing_blank_line_two_lines(self):
+        r = Result()
+        check_body(["fix: add thing", "body text"], r)
+        assert not r.ok
+        assert any("blank line" in msg for _, _, msg in r.errors)
+
     def test_blank_body_content(self):
         r = Result()
         check_body(["fix: add thing", "", "   "], r)