Add `git_reference_is_note`.

include/git2/refs.h

@@ -510,6 +510,16 @@ GIT_EXTERN(int) git_reference_is_remote(git_reference *ref);
  */
 GIT_EXTERN(int) git_reference_is_tag(git_reference *ref);
 
+/**
+ * Check if a reference is a note
+ *
+ * @param ref A git reference
+ *
+ * @return 1 when the reference lives in the refs/notes
+ * namespace; 0 otherwise.
+ */
+GIT_EXTERN(int) git_reference_is_note(git_reference *ref);
+
 typedef enum {
 	GIT_REF_FORMAT_NORMAL = 0u,
 

src/refs.c

@@ -1113,6 +1113,17 @@ int git_reference_is_tag(git_reference *ref)
 	return git_reference__is_tag(ref->name);
 }
 
+int git_reference__is_note(const char *ref_name)
+{
+	return git__prefixcmp(ref_name, GIT_REFS_NOTES_DIR) == 0;
+}
+
+int git_reference_is_note(git_reference *ref)
+{
+	assert(ref);
+	return git_reference__is_note(ref->name);
+}
+
 static int peel_error(int error, git_reference *ref, const char* msg)
 {
 	giterr_set(

tests/refs/read.c

@@ -271,6 +271,21 @@ void test_refs_read__can_determine_if_a_reference_is_a_tag(void)
 	assert_is_tag("refs/remotes/test/master", false);
 }
 
+static void assert_is_note(const char *name, bool expected_noteness)
+{
+	git_reference *reference;
+	cl_git_pass(git_reference_lookup(&reference, g_repo, name));
+	cl_assert_equal_i(expected_noteness, git_reference_is_note(reference));
+	git_reference_free(reference);
+}
+
+void test_refs_read__can_determine_if_a_reference_is_a_note(void)
+{
+	assert_is_note("refs/notes/fanout", true);
+	assert_is_note("refs/heads/packed", false);
+	assert_is_note("refs/remotes/test/master", false);
+}
+
 void test_refs_read__invalid_name_returns_EINVALIDSPEC(void)
 {
 	git_reference *reference;