Add Array CC_padded(to:with:) and unit tests

Author: mickeyl

Sources/CornucopiaCore/Extensions/Array/Array+Padding.swift

@@ -0,0 +1,11 @@
+//
+//  Cornucopia – (C) Dr. Lauer Information Technology
+//
+public extension Array {
+
+    /// Returns a copy padded to at least the requested `length` using `element`.
+    func CC_padded(to length: Int, with element: Element) -> [Element] {
+        guard length > count else { return self }
+        return self + Array(repeating: element, count: length - count)
+    }
+}

Tests/CornucopiaCoreTests/Extensions/Array/ArrayPaddingTests.swift

@@ -0,0 +1,37 @@
+import XCTest
+
+import CornucopiaCore
+
+class ArrayPaddingTests: XCTestCase {
+
+    func testCC_paddedAddsElements() {
+        let given: [UInt8] = [0x01, 0x02]
+        let when = given.CC_padded(to: 4, with: 0xFF)
+        let expected: [UInt8] = [0x01, 0x02, 0xFF, 0xFF]
+        XCTAssertEqual(when, expected)
+    }
+
+    func testCC_paddedNoopWhenAlreadyLonger() {
+        let given = [1, 2, 3]
+        let when = given.CC_padded(to: 2, with: 0)
+        XCTAssertEqual(when, given)
+    }
+
+    func testCC_paddedNoopWhenExactLength() {
+        let given = ["a", "b"]
+        let when = given.CC_padded(to: 2, with: "z")
+        XCTAssertEqual(when, given)
+    }
+
+    func testCC_paddedEmptyArray() {
+        let given: [Int] = []
+        let when = given.CC_padded(to: 3, with: 7)
+        XCTAssertEqual(when, [7, 7, 7])
+    }
+
+    func testCC_paddedNegativeLengthNoop() {
+        let given = [1, 2]
+        let when = given.CC_padded(to: -1, with: 9)
+        XCTAssertEqual(when, given)
+    }
+}