diff --git a/tests/gtest/test_population_test_fixture.hpp b/tests/gtest/test_population_test_fixture.hpp
index aaca79aa..9cf1424a 100644
--- a/tests/gtest/test_population_test_fixture.hpp
+++ b/tests/gtest/test_population_test_fixture.hpp
@@ -2,65 +2,59 @@
 
 #include "population_dynamics/population/population.hpp"
 
-namespace
-{
-
-  // Use test fixture to reuse the same configuration of objects for
-  // several different tests. To use a test fixture, derive a class
-  // from testing::Test.
-  class PopulationInitializeTestFixture : public testing::Test
-  {
-    // Make members protected and they can be accessed from
-    // sub-classes.
-  protected:
-    // Use SetUp function to prepare the objects for each test.
-    // Use override in C++11 to make sure SetUp (e.g., not Setup with
-    // a lowercase u) is spelled
-    // correctly.
-    void SetUp() override
-    {
-      population.id_g = id_g;
-      population.nyears = nyears;
-      population.nseasons = nseasons;
-      population.nages = nages;
-      for (int i = 0; i < nfleets; i++)
-      {
-        auto fleet = std::make_shared<fims_popdy::Fleet<double>>();
-        population.fleets.push_back(fleet);
-      }
+namespace {
+
+// Use test fixture to reuse the same configuration of objects for
+// several different tests. To use a test fixture, derive a class
+// from testing::Test.
+class PopulationInitializeTestFixture : public testing::Test {
+  // Make members protected and they can be accessed from
+  // sub-classes.
+ protected:
+  // Use SetUp function to prepare the objects for each test.
+  // Use override in C++11 to make sure SetUp (e.g., not Setup with
+  // a lowercase u) is spelled
+  // correctly.
+  void SetUp() override {
+    population.id_g = id_g;
+    population.nyears = nyears;
+    population.nseasons = nseasons;
+    population.nages = nages;
+    for (int i = 0; i < nfleets; i++) {
+      auto fleet = std::make_shared<fims_popdy::Fleet<double>>();
+      population.fleets.push_back(fleet);
     }
-
-    // Virtual void TearDown() will be called after each test is
-    // run. It needs to be defined if there is clearup work to
-    // do. Otherwise, it does not need to be provided.
-    virtual void TearDown() {}
-
-    fims_popdy::Population<double> population;
-
-    // Use default values from the Li et al., 2021
-    // https://github.com/Bai-Li-NOAA/Age_Structured_Stock_Assessment_Model_Comparison/blob/master/R/save_initial_input.R
-    int id_g = 0;
-    int nyears = 30;
-    int nseasons = 1;
-    int nages = 12;
-    int nfleets = 2;
-  };
-
-  class PopulationEvaluateTestFixture : public testing::Test
-  {
-  protected:
-    void SetUp() override
-    {
-      population.id_g = id_g;
-      population.nyears = nyears;
-      population.nseasons = nseasons;
-      population.nages = nages;
-      population.nfleets = nfleets;
-
-      // C++ code to set up true values for log_naa, log_M,
-      // log_Fmort, and log_q:
-      int seed = 1234;
-      std::default_random_engine generator(seed);
+  }
+
+  // Virtual void TearDown() will be called after each test is
+  // run. It needs to be defined if there is clearup work to
+  // do. Otherwise, it does not need to be provided.
+  virtual void TearDown() {}
+
+  fims_popdy::Population<double> population;
+
+  // Use default values from the Li et al., 2021
+  // https://github.com/Bai-Li-NOAA/Age_Structured_Stock_Assessment_Model_Comparison/blob/master/R/save_initial_input.R
+  int id_g = 0;
+  int nyears = 30;
+  int nseasons = 1;
+  int nages = 12;
+  int nfleets = 2;
+};
+
+class PopulationEvaluateTestFixture : public testing::Test {
+ protected:
+  void SetUp() override {
+    population.id_g = id_g;
+    population.nyears = nyears;
+    population.nseasons = nseasons;
+    population.nages = nages;
+    population.nfleets = nfleets;
+
+    // C++ code to set up true values for log_naa, log_M,
+    // log_Fmort, and log_q:
+    int seed = 1234;
+    std::default_random_engine generator(seed);
 
     // log_Fmort
     double log_Fmort_min = fims_math::log(0.1);
@@ -80,242 +74,224 @@ namespace
     // and population object needs a shared pointer in population.hpp
     // (std::vector<std::shared_ptr<fims_popdy::Fleet<Type> > > fleets;)
 
-      // Does Fmort need to be in side of the year loop like log_q?
-      for (int i = 0; i < nfleets; i++)
-      {
-        auto fleet = std::make_shared<fims_popdy::Fleet<double>>();
-        auto selectivity =
+    // Does Fmort need to be in side of the year loop like log_q?
+    for (int i = 0; i < nfleets; i++) {
+      auto fleet = std::make_shared<fims_popdy::Fleet<double>>();
+      auto selectivity =
           std::make_shared<fims_popdy::LogisticSelectivity<double>>();
-        selectivity->inflection_point = 7;
-        selectivity->slope = 0.5;
-
-        fleet->Initialize(nyears, nages);
-        fleet->selectivity = selectivity;
-        fleet->log_q = log_q_distribution(generator);
-        for (int year = 0; year < nyears; year++)
-        {
-          fleet->log_Fmort[year] = log_Fmort_distribution(generator);
-        }
-        if (i == 0)
-        {
-          fleet->is_survey = true;
-        }
-        fleet->Prepare();
-        population.fleets.push_back(fleet);
+      selectivity->inflection_point = 7;
+      selectivity->slope = 0.5;
+
+      fleet->Initialize(nyears, nages);
+      fleet->selectivity = selectivity;
+      fleet->log_q = log_q_distribution(generator);
+      for (int year = 0; year < nyears; year++) {
+        fleet->log_Fmort[year] = log_Fmort_distribution(generator);
       }
-
-      population.Initialize(nyears, nseasons, nages);
-
-      for (int i = 0; i < nages; i++)
-      {
-        population.ages[i] = i + 1;
+      if (i == 0) {
+        fleet->is_survey = true;
       }
+      fleet->Prepare();
+      population.fleets.push_back(fleet);
+    }
 
-      // log_naa
-      double log_init_naa_min = 10.0;
-      double log_init_naa_max = 12.0;
-      std::uniform_real_distribution<double> log_naa_distribution(
-          log_init_naa_min, log_init_naa_max);
-      for (int i = 0; i < nages; i++)
-      {
-        population.log_init_naa[i] = log_naa_distribution(generator);
-      }
+    population.Initialize(nyears, nseasons, nages);
 
-      // log_M
-      double log_M_min = fims_math::log(0.1);
-      double log_M_max = fims_math::log(0.3);
-      std::uniform_real_distribution<double> log_M_distribution(log_M_min,
-                                                                log_M_max);
-      for (int i = 0; i < nyears * nages; i++)
-      {
-        population.log_M[i] = log_M_distribution(generator);
-      }
+    for (int i = 0; i < nages; i++) {
+      population.ages[i] = i + 1;
+    }
 
-      // numbers_at_age
-      double numbers_at_age_min = fims_math::exp(10.0);
-      double numbers_at_age_max = fims_math::exp(12.0);
-      std::uniform_real_distribution<double> numbers_at_age_distribution(
-          numbers_at_age_min, numbers_at_age_max);
-      for (int i = 0; i < (nyears + 1) * nages; i++)
-      {
-        population.numbers_at_age[i] = numbers_at_age_distribution(generator);
-      }
+    // log_naa
+    double log_init_naa_min = 10.0;
+    double log_init_naa_max = 12.0;
+    std::uniform_real_distribution<double> log_naa_distribution(
+        log_init_naa_min, log_init_naa_max);
+    for (int i = 0; i < nages; i++) {
+      population.log_init_naa[i] = log_naa_distribution(generator);
+    }
 
-      // weight_at_age
-      double weight_at_age_min = 0.5;
-      double weight_at_age_max = 12.0;
-
-      std::shared_ptr<fims_popdy::EWAAgrowth<double>> growth =
-          std::make_shared<fims_popdy::EWAAgrowth<double>>();
-      std::uniform_real_distribution<double> weight_at_age_distribution(
-          weight_at_age_min, weight_at_age_max);
-      for (int i = 0; i < nages; i++)
-      {
-        growth->ewaa[static_cast<double>(population.ages[i])] =
-            weight_at_age_distribution(generator);
-      }
+    // log_M
+    double log_M_min = fims_math::log(0.1);
+    double log_M_max = fims_math::log(0.3);
+    std::uniform_real_distribution<double> log_M_distribution(log_M_min,
+                                                              log_M_max);
+    for (int i = 0; i < nyears * nages; i++) {
+      population.log_M[i] = log_M_distribution(generator);
+    }
 
-      population.growth = growth;
+    // numbers_at_age
+    double numbers_at_age_min = fims_math::exp(10.0);
+    double numbers_at_age_max = fims_math::exp(12.0);
+    std::uniform_real_distribution<double> numbers_at_age_distribution(
+        numbers_at_age_min, numbers_at_age_max);
+    for (int i = 0; i < (nyears + 1) * nages; i++) {
+      population.numbers_at_age[i] = numbers_at_age_distribution(generator);
+    }
 
-      population.Prepare();
+    // weight_at_age
+    double weight_at_age_min = 0.5;
+    double weight_at_age_max = 12.0;
+
+    std::shared_ptr<fims_popdy::EWAAgrowth<double>> growth =
+        std::make_shared<fims_popdy::EWAAgrowth<double>>();
+    std::uniform_real_distribution<double> weight_at_age_distribution(
+        weight_at_age_min, weight_at_age_max);
+    for (int i = 0; i < nages; i++) {
+      growth->ewaa[static_cast<double>(population.ages[i])] =
+          weight_at_age_distribution(generator);
+    }
 
-      auto maturity = std::make_shared<fims_popdy::LogisticMaturity<double>>();
-      maturity->inflection_point = 6;
-      maturity->slope = 0.15;
-      population.maturity = maturity;
+    population.growth = growth;
 
-      auto recruitment = std::make_shared<fims_popdy::SRBevertonHolt<double>>();
-      recruitment->logit_steep = fims_math::logit(0.2, 1.0, 0.75);
-      recruitment->log_rzero = fims_math::log(1000000.0);
-      recruitment->recruit_deviations.resize(nyears);
-      for (int i = 0; i < recruitment->recruit_deviations.size(); i++) {
-        recruitment->recruit_deviations[i] = 1.0;
-      }
-      population.recruitment = recruitment;
+    population.Prepare();
 
-      int year = 4;
-      int age = 6;
-      int i_age_year = year * population.nages + age;
-      int i_agem1_yearm1 = (year - 1) * population.nages + age - 1;
+    auto maturity = std::make_shared<fims_popdy::LogisticMaturity<double>>();
+    maturity->inflection_point = 6;
+    maturity->slope = 0.15;
+    population.maturity = maturity;
 
-      population.CalculateMortality(i_age_year, year, age);
-      population.CalculateNumbersAA(i_age_year, i_agem1_yearm1, age);
+    auto recruitment = std::make_shared<fims_popdy::SRBevertonHolt<double>>();
+    recruitment->logit_steep = fims_math::logit(0.2, 1.0, 0.75);
+    recruitment->log_rzero = fims_math::log(1000000.0);
+    recruitment->recruit_deviations.resize(nyears);
+    for (int i = 0; i < recruitment->recruit_deviations.size(); i++) {
+      recruitment->recruit_deviations[i] = 1.0;
     }
-
-    virtual void TearDown() {}
-
-    fims_popdy::Population<double> population;
-    int id_g = 0;
-    int nyears = 30;
-    int nseasons = 1;
-    int nages = 12;
-    int nfleets = 2;
+    population.recruitment = recruitment;
 
     int year = 4;
     int age = 6;
-    int i_age_year = year * nages + age;
-    int i_agem1_yearm1 = (year - 1) * nages + age - 1;
-    
-  };
-
-  class PopulationPrepareTestFixture : public testing::Test
-  {
-  protected:
-    void SetUp() override
-    {
-      population.id_g = id_g;
-      population.nyears = nyears;
-      population.nseasons = nseasons;
-      population.nages = nages;
-      population.nfleets = nfleets;
-
-      // C++ code to set up true values for log_Fmort, and log_q:
-      int seed = 1234;
-      std::default_random_engine generator(seed);
-
-      // log_Fmort
-      double log_Fmort_min = fims_math::log(0.1);
-      double log_Fmort_max = fims_math::log(2.3);
-      std::uniform_real_distribution<double> log_Fmort_distribution(
-          log_Fmort_min, log_Fmort_max);
-
-      // log_q
-      double log_q_min = fims_math::log(0.1);
-      double log_q_max = fims_math::log(1);
-      std::uniform_real_distribution<double> log_q_distribution(log_q_min,
-                                                                log_q_max);
-
-      // Make a shared pointer to selectivity and fleet because
-      // fleet object needs a shared pointer in fleet.hpp
-      // (std::shared_ptr<fims::SelectivityBase<Type> > selectivity;)
-      // and population object needs a shared pointer in population.hpp
-      // (std::vector<std::shared_ptr<fims::Fleet<Type> > > fleets;)
-
-      for (int i = 0; i < nfleets; i++)
-      {
-        auto fleet = std::make_shared<fims_popdy::Fleet<double>>();
-        auto selectivity = std::make_shared<fims_popdy::LogisticSelectivity<double>>();
-        selectivity->inflection_point = 7;
-        selectivity->slope = 0.5;
-
-        fleet->Initialize(nyears, nages);
-        fleet->selectivity = selectivity;
-        fleet->log_q = log_q_distribution(generator);
-        for (int year = 0; year < nyears; year++)
-        {
-          fleet->log_Fmort[year] = log_Fmort_distribution(generator);
-        }
-        if (i == 0)
-        {
-          fleet->is_survey = true;
-        }
-        fleet->Prepare();
-        population.fleets.push_back(fleet);
-      }
+    int i_age_year = year * population.nages + age;
+    int i_agem1_yearm1 = (year - 1) * population.nages + age - 1;
+
+    population.CalculateMortality(i_age_year, year, age);
+    population.CalculateNumbersAA(i_age_year, i_agem1_yearm1, age);
+  }
+
+  virtual void TearDown() {}
+
+  fims_popdy::Population<double> population;
+  int id_g = 0;
+  int nyears = 30;
+  int nseasons = 1;
+  int nages = 12;
+  int nfleets = 2;
+
+  int year = 4;
+  int age = 6;
+  int i_age_year = year * nages + age;
+  int i_agem1_yearm1 = (year - 1) * nages + age - 1;
+};
+
+class PopulationPrepareTestFixture : public testing::Test {
+ protected:
+  void SetUp() override {
+    population.id_g = id_g;
+    population.nyears = nyears;
+    population.nseasons = nseasons;
+    population.nages = nages;
+    population.nfleets = nfleets;
+
+    // C++ code to set up true values for log_Fmort, and log_q:
+    int seed = 1234;
+    std::default_random_engine generator(seed);
+
+    // log_Fmort
+    double log_Fmort_min = fims_math::log(0.1);
+    double log_Fmort_max = fims_math::log(2.3);
+    std::uniform_real_distribution<double> log_Fmort_distribution(
+        log_Fmort_min, log_Fmort_max);
 
-      population.Initialize(nyears, nseasons, nages);
+    // log_q
+    double log_q_min = fims_math::log(0.1);
+    double log_q_max = fims_math::log(1);
+    std::uniform_real_distribution<double> log_q_distribution(log_q_min,
+                                                              log_q_max);
 
-      for (int i = 0; i < nages; i++)
-      {
-        population.ages[i] = i + 1;
-      }
+    // Make a shared pointer to selectivity and fleet because
+    // fleet object needs a shared pointer in fleet.hpp
+    // (std::shared_ptr<fims::SelectivityBase<Type> > selectivity;)
+    // and population object needs a shared pointer in population.hpp
+    // (std::vector<std::shared_ptr<fims::Fleet<Type> > > fleets;)
 
-      // log_naa
-      double log_init_naa_min = 10.0;
-      double log_init_naa_max = 12.0;
-      std::uniform_real_distribution<double> log_naa_distribution(
-          log_init_naa_min, log_init_naa_max);
-      for (int i = 0; i < nages; i++)
-      {
-        population.log_init_naa[i] = log_naa_distribution(generator);
+    for (int i = 0; i < nfleets; i++) {
+      auto fleet = std::make_shared<fims_popdy::Fleet<double>>();
+      auto selectivity =
+          std::make_shared<fims_popdy::LogisticSelectivity<double>>();
+      selectivity->inflection_point = 7;
+      selectivity->slope = 0.5;
+
+      fleet->Initialize(nyears, nages);
+      fleet->selectivity = selectivity;
+      fleet->log_q = log_q_distribution(generator);
+      for (int year = 0; year < nyears; year++) {
+        fleet->log_Fmort[year] = log_Fmort_distribution(generator);
       }
-
-      // log_M
-      double log_M_min = fims_math::log(0.1);
-      double log_M_max = fims_math::log(0.3);
-      std::uniform_real_distribution<double> log_M_distribution(log_M_min,
-                                                                log_M_max);
-      for (int i = 0; i < nyears * nages; i++)
-      {
-        population.log_M[i] = log_M_distribution(generator);
+      if (i == 0) {
+        fleet->is_survey = true;
       }
+      fleet->Prepare();
+      population.fleets.push_back(fleet);
+    }
 
-      // numbers_at_age
-      double numbers_at_age_min = fims_math::exp(10.0);
-      double numbers_at_age_max = fims_math::exp(12.0);
-      std::uniform_real_distribution<double> numbers_at_age_distribution(
-          numbers_at_age_min, numbers_at_age_max);
-      for (int i = 0; i < (nyears + 1) * nages; i++)
-      {
-        population.numbers_at_age[i] = numbers_at_age_distribution(generator);
-      }
+    population.Initialize(nyears, nseasons, nages);
 
-      // weight_at_age
-      double weight_at_age_min = 0.5;
-      double weight_at_age_max = 12.0;
-
-      std::shared_ptr<fims_popdy::EWAAgrowth<double>> growth =
-          std::make_shared<fims_popdy::EWAAgrowth<double>>();
-      std::uniform_real_distribution<double> weight_at_age_distribution(
-          weight_at_age_min, weight_at_age_max);
-      for (int i = 0; i < nages; i++)
-      {
-        growth->ewaa[static_cast<double>(population.ages[i])] =
-            weight_at_age_distribution(generator);
-      }
+    for (int i = 0; i < nages; i++) {
+      population.ages[i] = i + 1;
+    }
 
-      population.growth = growth;
+    // log_naa
+    double log_init_naa_min = 10.0;
+    double log_init_naa_max = 12.0;
+    std::uniform_real_distribution<double> log_naa_distribution(
+        log_init_naa_min, log_init_naa_max);
+    for (int i = 0; i < nages; i++) {
+      population.log_init_naa[i] = log_naa_distribution(generator);
+    }
 
-      population.Prepare();
+    // log_M
+    double log_M_min = fims_math::log(0.1);
+    double log_M_max = fims_math::log(0.3);
+    std::uniform_real_distribution<double> log_M_distribution(log_M_min,
+                                                              log_M_max);
+    for (int i = 0; i < nyears * nages; i++) {
+      population.log_M[i] = log_M_distribution(generator);
     }
 
-    virtual void TearDown() {}
+    // numbers_at_age
+    double numbers_at_age_min = fims_math::exp(10.0);
+    double numbers_at_age_max = fims_math::exp(12.0);
+    std::uniform_real_distribution<double> numbers_at_age_distribution(
+        numbers_at_age_min, numbers_at_age_max);
+    for (int i = 0; i < (nyears + 1) * nages; i++) {
+      population.numbers_at_age[i] = numbers_at_age_distribution(generator);
+    }
+
+    // weight_at_age
+    double weight_at_age_min = 0.5;
+    double weight_at_age_max = 12.0;
+
+    std::shared_ptr<fims_popdy::EWAAgrowth<double>> growth =
+        std::make_shared<fims_popdy::EWAAgrowth<double>>();
+    std::uniform_real_distribution<double> weight_at_age_distribution(
+        weight_at_age_min, weight_at_age_max);
+    for (int i = 0; i < nages; i++) {
+      growth->ewaa[static_cast<double>(population.ages[i])] =
+          weight_at_age_distribution(generator);
+    }
+
+    population.growth = growth;
+
+    population.Prepare();
+  }
+
+  virtual void TearDown() {}
 
-    fims_popdy::Population<double> population;
-    int id_g = 0;
-    int nyears = 30;
-    int nseasons = 1;
-    int nages = 12;
-    int nfleets = 2;
-  };
-} // namespace
\ No newline at end of file
+  fims_popdy::Population<double> population;
+  int id_g = 0;
+  int nyears = 30;
+  int nseasons = 1;
+  int nages = 12;
+  int nfleets = 2;
+};
+}  // namespace
\ No newline at end of file