Add FloatingPoint.percent methods

- TOOO: Implement for integers
- TODO: Tests

Author: ShinryakuTako

Sources/OctopusKit/Apple API Extensions/Foundation/FloatingPoint+OctopusKit.swift

@@ -11,7 +11,7 @@
 import Foundation
 
 public extension FloatingPoint {
-     
+    
     // MARK: - Random Numbers
 
     /// Shorthand for `Self(Int.random(in: range))`
@@ -41,4 +41,23 @@ public extension FloatingPoint {
     {
         Self(Int.random(in: range, using: &generator))
     }
+    
+    // MARK: - Percentages
+    
+    /// Returns the specified percentage of `self`.
+    @inlinable
+    func percent(_ percent: Self) -> Self {
+        // TODO: Apply this extension to integers too?
+        return self * (percent / 100)
+    }
+    
+    /// Returns `self` percent of the specified `value`.
+    ///
+    /// **Example:** `10.percent(of: 50)` returns `5`
+    @inlinable
+    func percent(of value: Self) -> Self {
+        // TODO: Apply this extension to integers too?
+        return value * (self / 100)
+    }
+
 }

Tests/OctopusKitTests/Apple API Extensions Tests/NumericsTests.swift

@@ -44,7 +44,7 @@ class NumericsTests: XCTestCase {
 
         // #2: Test floats
 
-        XCTContext.runActivity(named: "Test integers") { _ in
+        XCTContext.runActivity(named: "Test floats") { _ in
             var value: Float = 10.0
 
             // #2A: Difference = 0.1
@@ -72,7 +72,27 @@ class NumericsTests: XCTestCase {
 
     }
 
+    func testFloatingPoint() {
+        
+        // TODO: #1: Test percent(_:)
+        
+        /* NOTE: This test will fail because you're not supposed to directly compare floating point numbers.
+         
+        XCTContext.runActivity(named: "Test percent") { _ in
+            
+            // #1A: N% of 100 should be N
+            
+            for percent in 0...100 {
+                XCTAssertTrue(100.percent(Double(percent)).isEqual(to: Double(percent)))
+            }
+        }
+        */
+        
+        // TODO: #2: Test percent(of:)
+    }
+    
     static var allTests = [
-        ("Test AdditiveArithmetic extensions", testAdditiveArithmetic)
+        ("Test AdditiveArithmetic extensions", testAdditiveArithmetic),
+        ("Test FloatingPoint extensions", testFloatingPoint)
     ]
 }