add basic types and fix cmake

src/test/FormulaTest.cpp

@@ -0,0 +1,75 @@
+#include "catch.hpp"
+
+#include <stdexcept>
+
+#include "Formula.h"
+
+TEST_CASE("Formula compiles a constant expression", "[formula]")
+{
+    const Formula f = Formula::compile("42");
+
+    REQUIRE(f.isValid());
+    REQUIRE(f.evaluate(0.0)   == Approx(42.0));
+    REQUIRE(f.evaluate(100.0) == Approx(42.0));
+}
+
+TEST_CASE("Formula evaluates a linear expression in x", "[formula]")
+{
+    // Matches world.toml [waves].threat_rate_formula default.
+    const Formula f = Formula::compile("1*x - 30");
+
+    REQUIRE(f.evaluate(0.0)  == Approx(-30.0));
+    REQUIRE(f.evaluate(30.0) == Approx(0.0));
+    REQUIRE(f.evaluate(60.0) == Approx(30.0));
+}
+
+TEST_CASE("Formula evaluates a polynomial in x", "[formula]")
+{
+    const Formula f = Formula::compile("2 + 3*x*x");
+
+    REQUIRE(f.evaluate(0.0) == Approx(2.0));
+    REQUIRE(f.evaluate(2.0) == Approx(14.0));
+    REQUIRE(f.evaluate(4.0) == Approx(50.0));
+}
+
+TEST_CASE("Formula retains its source string", "[formula]")
+{
+    const std::string source = "10 + x / 5";
+    const Formula f = Formula::compile(source);
+
+    REQUIRE(f.source() == source);
+}
+
+TEST_CASE("Formula throws on malformed source", "[formula]")
+{
+    REQUIRE_THROWS_AS(Formula::compile("1 * + x"),   std::runtime_error);
+    REQUIRE_THROWS_AS(Formula::compile(""),          std::runtime_error);
+    REQUIRE_THROWS_AS(Formula::compile("unknown_var"), std::runtime_error);
+}
+
+TEST_CASE("Formula survives move construction", "[formula]")
+{
+    // tinyexpr bakes the bound variable's address into the compiled tree.
+    // Formula keeps x on the heap so that address stays valid across moves.
+    Formula original = Formula::compile("x * 2");
+    Formula moved(std::move(original));
+
+    REQUIRE(moved.evaluate(21.0) == Approx(42.0));
+}
+
+TEST_CASE("Formula survives move assignment", "[formula]")
+{
+    Formula a = Formula::compile("x + 1");
+    Formula b = Formula::compile("x + 100");
+
+    b = std::move(a);
+
+    REQUIRE(b.evaluate(5.0) == Approx(6.0));
+}
+
+TEST_CASE("Default-constructed Formula is invalid and throws on evaluate", "[formula]")
+{
+    const Formula f;
+    REQUIRE_FALSE(f.isValid());
+    REQUIRE_THROWS_AS(f.evaluate(0.0), std::runtime_error);
+}