Gtest setup

.gitignore

@@ -6,3 +6,4 @@
 *.fls
 *.fdb_latexmk
 .vscode/
+build/

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "googletest"]
+	path = googletest
+	url = https://github.com/google/googletest

CMakeLists.txt

@@ -0,0 +1,13 @@
+cmake_minimum_required(VERSION 3.13)
+
+project(booklet LANGUAGES CXX)
+
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+
+include(CTest)
+enable_testing()
+
+add_subdirectory(tests)
+add_subdirectory(googletest)

Makefile

@@ -9,10 +9,14 @@ all:
 	mv main.pdf "$(PDFNAME)"
 
 clean:
-	-rm main.aux main.log main.out main.toc
+	-rm -r main.aux main.log main.out main.toc build
 
 distclean: clean
 	-rm "$(PDFNAME)"
 
 print-todos:
 	grep --color '\\todo{' main.tex content/*
+
+test:
+	mkdir -p build
+	cd build && cmake .. && make -j8 && ./tests/tests

tests/CMakeLists.txt

@@ -0,0 +1,28 @@
+cmake_minimum_required(VERSION 3.13)
+
+include(GoogleTest)
+
+set(TEST_SOURCES
+    test_fenwick.cpp
+    test_mod_inverse.cpp
+)
+
+add_executable(tests
+    ${TEST_SOURCES}
+)
+
+target_include_directories(tests
+    PUBLIC
+        ../source
+        ../googletest/include
+)
+
+set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
+
+target_link_libraries(tests
+    PUBLIC
+        gtest
+        gtest_main
+)
+
+gtest_discover_tests(tests)

tests/test_fenwick.cpp

@@ -0,0 +1,10 @@
+#include "gtest/gtest.h"
+#include "fenwick.h"
+
+TEST(fenwick, works) {
+    Fenwick ft(5);
+    EXPECT_EQ(ft.sum(0, 4), 0);
+    ft.add(2, 5);
+    EXPECT_EQ(ft.sum(0, 4), 5);
+    EXPECT_EQ(ft.sum(0, 1), 0);
+}

tests/test_mod_inverse.cpp

@@ -0,0 +1,21 @@
+#include "gtest/gtest.h"
+#include "mod_inverse.h"
+
+TEST(mod_inverse, correct) {
+    auto check = [](ll x, ll mod) {
+        auto inv = mod_inverse(x, mod);
+        return ((x * inv) % mod) == 1;
+    };
+
+    for(ll mod : {17, 1000000007, 1000000009}) {
+        for(ll x : {2, 50, 1000000000}) {
+            EXPECT_TRUE(check(x, mod));
+        }
+    }
+}
+
+TEST(mod_inverse, fails_if_not_coprime) {
+    EXPECT_EQ(mod_inverse(5, 10), -1);
+    EXPECT_EQ(mod_inverse(1000, 1000000), -1);
+    EXPECT_EQ(mod_inverse(1000000000, 8000000000), -1);
+}