Bit writers' align() now does nothing if writer is already aligned

This is consistent with readers' behaviour.

Author: tsolomko

Sources/LsbBitWriter.swift

@@ -72,6 +72,9 @@ public final class LsbBitWriter: BitWriter {
      - Note: If writer is already aligned, then does nothing.
      */
     public func align() {
+        guard self.bitMask != 1
+            else { return }
+
         self.data.append(self.currentByte)
         self.currentByte = 0
         self.bitMask = 1

Sources/MsbBitWriter.swift

@@ -72,6 +72,9 @@ public final class MsbBitWriter: BitWriter {
      - Note: If writer is already aligned, then does nothing.
      */
     public func align() {
+        guard self.bitMask != 128
+            else { return }
+
         self.data.append(self.currentByte)
         self.currentByte = 0
         self.bitMask = 128

Tests/BitByteDataTests/LsbBitWriterTests.swift

@@ -52,7 +52,7 @@ class LsbBitWriterTests: XCTestCase {
         let bitWriter = LsbBitWriter()
 
         bitWriter.align()
-        XCTAssertEqual(bitWriter.data, Data(bytes: [0]))
+        XCTAssertEqual(bitWriter.data, Data())
         XCTAssertTrue(bitWriter.isAligned)
     }
 

Tests/BitByteDataTests/MsbBitWriterTests.swift

@@ -55,7 +55,7 @@ class MsbBitWriterTests: XCTestCase {
         let bitWriter = MsbBitWriter()
 
         bitWriter.align()
-        XCTAssertEqual(bitWriter.data, Data(bytes: [0]))
+        XCTAssertEqual(bitWriter.data, Data())
         XCTAssertTrue(bitWriter.isAligned)
     }