Add less than comparison

src/Common/Interfaces/LinearDim.php

@@ -8,6 +8,7 @@ public function unit (): LinearUnit;
     public function times (float $multiplier): LinearDim;
     public function minus (LinearDim $dim): LinearDim;
     public function max (float $value): LinearDim;
+    public function lessThan (LinearDim $dim): bool;
 
     /**
      * @param \Dbt\Volumes\Common\Interfaces\LinearUnit|null $unit

src/ConicalFrustumWithAngle.php

@@ -26,6 +26,6 @@ public function __construct (
         $opposite = new Line(tan($angle->value()), $this->baseLinearUnit());
 
         /** @var RadialDim $bottom */
-        $this->bottom = $top->minus($opposite);
+        $this->bottom = $this->top->minus($opposite);
     }
 }

src/Dimensions/Line.php

@@ -2,6 +2,7 @@
 
 namespace Dbt\Volumes\Dimensions;
 
+use Dbt\Volumes\Common\Exceptions\WrongUnit;
 use Dbt\Volumes\Common\Interfaces\Dim;
 use Dbt\Volumes\Common\Interfaces\LinearDim;
 use Dbt\Volumes\Common\Interfaces\LinearUnit;
@@ -52,13 +53,37 @@ public function times (float $multiplier): LinearDim
         return $this->of($this->value() * $multiplier);
     }
 
+    public function max (float $value): LinearDim
+    {
+        return $this->of(max($value, $this->value()));
+    }
+
     public function minus (LinearDim $dim): LinearDim
     {
+        $this->assertSameUnit($dim);
+
         return $this->of($this->value() - $dim->value());
     }
 
-    public function max (float $value): LinearDim
+    /*
+     * Comparison
+     */
+
+    public function lessThan (LinearDim $dim): bool
     {
-        return $this->of(max($value, $this->value()));
+        $this->assertSameUnit($dim);
+
+        return $this->value() < $dim->value();
+    }
+
+    /*
+     * Assertions
+     */
+
+    private function assertSameUnit (LinearDim $dim): void
+    {
+        if (!$this->hasSameUnit($dim)) {
+            throw new WrongUnit();
+        }
     }
 }

tests/Dimensions/LineTest.php

@@ -2,6 +2,7 @@
 
 namespace Dbt\Volumes\Tests\Dimensions;
 
+use Dbt\Volumes\Common\Exceptions\WrongUnit;
 use Dbt\Volumes\Dimensions\Line;
 use Dbt\Volumes\Tests\UnitTestCase;
 use Dbt\Volumes\Units\Inch;
@@ -85,4 +86,32 @@ public function maxing_immutably ()
             $voNeg->max($max)->value()
         );
     }
+
+    /** @test */
+    public function comparing ()
+    {
+        $lower = (float) rand(1, 99);
+        $upper = (float) rand(100, 199);
+        $unit = new None();
+
+        $vo1 = new Line($lower, $unit);
+        $vo2 = new Line($upper, $unit);
+
+        $this->assertTrue($vo1->lessThan($vo2));
+        $this->assertFalse($vo2->lessThan($vo1));
+    }
+
+    /** @test */
+    public function failing_to_compare ()
+    {
+        $this->expectException(WrongUnit::class);
+
+        $lower = (float) rand(1, 99);
+        $upper = (float) rand(100, 199);
+
+        $vo1 = new Line($lower, new Inch());
+        $vo2 = new Line($upper, new Millimeter());
+
+        $vo1->lessThan($vo2);
+    }
 }