From 3397bf431044cca2fd43e38889d8c61bebb8c6e3 Mon Sep 17 00:00:00 2001
From: Bruno BELANYI <bruno@belanyi.fr>
Date: Sat, 21 Aug 2021 12:48:37 +0200
Subject: [PATCH] abacus: bignum: fix order comparisons

This is a pretty big oversight...
---
 src/bignum/bignum.cc | 4 ++++
 tests/unit/bignum.cc | 8 ++++++++
 2 files changed, 12 insertions(+)

diff --git a/src/bignum/bignum.cc b/src/bignum/bignum.cc
index a074ba9..abf0b5f 100644
--- a/src/bignum/bignum.cc
+++ b/src/bignum/bignum.cc
@@ -16,6 +16,10 @@ namespace {
 auto static constexpr BASE = 10;
 
 bool do_less_than(digits_type const& lhs, digits_type const& rhs) {
+    if (lhs.size() != rhs.size()) {
+        return lhs.size() < rhs.size();
+    }
+
     return std::lexicographical_compare(lhs.rbegin(), lhs.rend(), rhs.rbegin(),
                                         rhs.rend());
 }
diff --git a/tests/unit/bignum.cc b/tests/unit/bignum.cc
index 0454414..86c6178 100644
--- a/tests/unit/bignum.cc
+++ b/tests/unit/bignum.cc
@@ -60,6 +60,14 @@ TEST(BigNum, comparisons) {
     EXPECT_GE(one, one);
 }
 
+TEST(BigNum, comparisons_digits) {
+    auto const nine = BigNum(9);
+    auto const ten = BigNum(10);
+
+    EXPECT_LT(nine, ten);
+    EXPECT_GT(ten, nine);
+}
+
 TEST(BigNum, unary) {
     auto const zero = BigNum(0);
     auto const one = BigNum(1);