From 15011715e7be8958964041cc33833afe1cf2bc1e Mon Sep 17 00:00:00 2001
From: mikael <mlund@mac.com>
Date: Sun, 16 Jun 2024 18:38:19 +0200
Subject: [PATCH] Tidy random

---
 src/random.cpp | 37 ++++++++++++++++++-------------------
 src/random.h   |  4 ++--
 2 files changed, 20 insertions(+), 21 deletions(-)

diff --git a/src/random.cpp b/src/random.cpp
index e03be3d65..12614098f 100644
--- a/src/random.cpp
+++ b/src/random.cpp
@@ -1,28 +1,27 @@
 #include <doctest/doctest.h>
 #include "random.h"
 #include <nlohmann/json.hpp>
-#include <stdexcept>
 #include <iostream>
 #include <string>
 #include <sstream>
 
 namespace Faunus {
 
-void from_json(const nlohmann::json &j, Random &random) {
+void from_json(const nlohmann::json &j, Random & rng) {
     if (j.is_object()) {
         auto seed = j.value("seed", std::string());
         try {
             if (seed == "default" or seed == "fixed") { // use default seed, i.e. do nothing
                 return;
             } else if (seed == "hardware") { // use hardware seed
-                random.engine = decltype(random.engine)(std::random_device()());
+                rng.engine = decltype(rng.engine)(std::random_device()());
             } else if (!seed.empty()) { // read engine state
                 std::stringstream stream(seed);
                 stream.exceptions(std::ios::badbit | std::ios::failbit);
-                stream >> random.engine;
+                stream >> rng.engine;
             }
         } catch (std::exception &e) {
-            std::cerr << "could not initialize random engine - falling back to fixed seed." << std::endl;
+            std::cerr << "could not initialize rng engine - falling back to fixed seed." << std::endl;
         }
     }
 }
@@ -52,7 +51,7 @@ TEST_CASE("[Faunus] Random") {
     using namespace Faunus;
     Random slump, slump2; // local instances
 
-    CHECK(slump() == slump2()); // deterministic initialization by default; the global random variable cannot
+    CHECK_EQ(slump(), slump2()); // deterministic initialization by default; the global random variable cannot
                                 // be used for comparison as its state is not reset at the beginning of
                                 // each test case
 
@@ -66,22 +65,22 @@ TEST_CASE("[Faunus] Random") {
             max = j;
         x += j;
     }
-    CHECK(min == 0);
-    CHECK(max == 9);
-    CHECK(std::fabs(x / N) == doctest::Approx(4.5).epsilon(0.01));
+    CHECK_EQ(min, 0);
+    CHECK_EQ(max, 9);
+    CHECK_EQ(std::fabs(x / N), doctest::Approx(4.5).epsilon(0.01));
 
     Random r1 = R"( {"seed" : "hardware"} )"_json; // non-deterministic seed
     Random r2;                                     // default is a deterministic seed
-    CHECK(r1() != r2());
+    CHECK((r1() != r2()));
     Random r3 = nlohmann::json(r1); // r1 --> json --> r3
-    CHECK(r1() == r3());
+    CHECK_EQ(r1(), r3());
 
     // check if random_device works
     Random a, b;
-    CHECK(a() == b());
+    CHECK_EQ(a(), b());
     a.seed();
     b.seed();
-    CHECK(a() != b());
+    CHECK((a() != b()));
 }
 
 TEST_CASE("[Faunus] WeightedDistribution") {
@@ -89,12 +88,12 @@ TEST_CASE("[Faunus] WeightedDistribution") {
     WeightedDistribution<double> v;
 
     v.push_back(0.5);
-    CHECK(v.getLastIndex() == 0);
-    CHECK(v.size() == 1);
+    CHECK_EQ(v.getLastIndex(), 0);
+    CHECK_EQ(v.size(), 1);
 
     v.push_back(0.1, 4);
-    CHECK(v.getLastIndex() == 1);
-    CHECK(v.size() == 2);
+    CHECK_EQ(v.getLastIndex(), 1);
+    CHECK_EQ(v.size(), 2);
     CHECK(not v.empty());
 
     int N = 1e4;
@@ -102,7 +101,7 @@ TEST_CASE("[Faunus] WeightedDistribution") {
     for (int i = 0; i < N; i++) {
         sum += v.sample(Faunus::random.engine);
     }
-    CHECK(sum / N == doctest::Approx((0.5 * 1 + 0.1 * 4) / (1 + 4)).epsilon(0.05));
+    CHECK_EQ(sum / N, doctest::Approx((0.5 * 1 + 0.1 * 4) / (1 + 4)).epsilon(0.05));
 
     std::vector<int> weights = {2, 1};
     v.setWeight(weights.begin(), weights.end());
@@ -110,7 +109,7 @@ TEST_CASE("[Faunus] WeightedDistribution") {
     for (int i = 0; i < N; i++) {
         sum += v.sample(Faunus::random.engine);
     }
-    CHECK(sum / N == doctest::Approx((0.5 * 2 + 0.1 * 1) / (2 + 1)).epsilon(0.05));
+    CHECK_EQ(sum / N, doctest::Approx((0.5 * 2 + 0.1 * 1) / (2 + 1)).epsilon(0.05));
 
     weights = {2, 1, 1};
     CHECK_THROWS(v.setWeight(weights.begin(), weights.end()));
diff --git a/src/random.h b/src/random.h
index 972916a7e..49b1703c1 100644
--- a/src/random.h
+++ b/src/random.h
@@ -83,8 +83,8 @@ template <typename T> class WeightedDistribution {
   public:
     std::vector<T> data;                        //!< raw vector of T
     auto size() const { return data.size(); }   //!< Number of data points
-    bool empty() const { return data.empty(); } //!< True if no data points
-    size_t getLastIndex() const {
+    [[nodiscard]] bool empty() const { return data.empty(); } //!< True if no data points
+    [[nodiscard]] size_t getLastIndex() const {
         assert(!data.empty());
         return latest_index;
     } //!< index of last `get()` or `addGroup()` element