Add truncation for quantify::transposition_growth

And also coverage for nested::fast_reduce

src/adiar/exec_policy.h

@@ -126,12 +126,15 @@ namespace adiar
       //////////////////////////////////////////////////////////////////////////
       class transposition_growth
       {
+      private:
+        static constexpr float min_val = 0.0f;
+
       public:
         /// \brief Minimal value
         static constexpr transposition_growth
         min()
         {
-          return 0.0f;
+          return min_val;
         }
 
         /// \brief Maximal value
@@ -144,14 +147,22 @@ namespace adiar
       private:
         float _value;
 
+        /// \brief Convert into a `signed char`
+        static constexpr float
+        from_float(float f)
+        {
+          // Truncate `f` to be in the interval [0.0f, ...)
+          return f < min_val ? min_val : f;
+        }
+
       public:
         constexpr transposition_growth()
           : _value(1.5f)
         { }
 
         /// \brief Wrap a `float`.
         constexpr transposition_growth(float value)
-          : _value(value)
+          : _value(from_float(value))
         {}
 
         /// \brief Reobtain the wrapped `float`

test/adiar/test_exec_policy.cpp

@@ -16,14 +16,25 @@ go_bandit([]() {
           AssertThat(default__transposition_growth, Is().GreaterThanOrEqualTo(0.0f));
         });
 
-        it("'quantify::transposition max' defaults to a non-negative value", [&]() {
-          AssertThat(default__transposition_max, Is().GreaterThanOrEqualTo(0u));
+        it("'quantify::transposition growth' truncates negative values to '0.0f'", [&]() {
+          const exec_policy::quantify::transposition_growth res(-0.5f);
+          AssertThat(static_cast<float>(res), Is().GreaterThanOrEqualTo(0.0f));
         });
 
         it("'nested::fast reduce epsilon' defaults to a value in [-1,1]", [&]() {
           AssertThat(default__fast_reduce, Is().GreaterThanOrEqualTo(-1.0f));
           AssertThat(default__fast_reduce, Is().LessThanOrEqualTo(1.0f));
         });
+
+        it("'nested::fast reduce epsilon' truncates negative values to '-1.0f'", [&]() {
+          const exec_policy::nested::fast_reduce res(-42.0f);
+          AssertThat(static_cast<float>(res), Is().EqualTo(-1.0f));
+        });
+
+        it("'nested::fast reduce epsilon' truncates positive value to '1.0f'", [&]() {
+          const exec_policy::nested::fast_reduce res(2.0f);
+          AssertThat(static_cast<float>(res), Is().EqualTo(1.0f));
+        });
       });
 
       describe("exec_policy(const __ &)", [&]() {