Add new class files with Unit tests for tracking the history.

app/src/main/java/me/zobrist/tichucounter/History.kt

@@ -0,0 +1,55 @@
+package me.zobrist.tichucounter
+
+class History {
+    private var scores: ArrayList<Round> = ArrayList()
+
+    fun getScoreA(): Int {
+        var tempScore = 0
+        scores.forEach {
+            tempScore += it.scoreA
+        }
+        return tempScore
+    }
+
+    fun getScoreB(): Int {
+        var tempScore = 0
+        scores.forEach {
+            tempScore += it.scoreB
+        }
+        return tempScore
+    }
+
+    fun getHistoryA(): String {
+        var tempHistory = String()
+        scores.forEach {
+            tempHistory = tempHistory.plus(it.scoreA.toString()).plus("\n")
+        }
+        return tempHistory
+    }
+
+    fun getHistoryB(): String {
+        var tempHistory = String()
+        scores.forEach {
+            tempHistory = tempHistory.plus(it.scoreB.toString()).plus("\n")
+        }
+        return tempHistory
+    }
+
+    fun logRound(round: Round) {
+        scores.add(round)
+    }
+
+    fun revertLastRound() {
+        if (scores.isNotEmpty()) {
+            scores.removeAt(scores.size - 1)
+        }
+    }
+
+    fun clearAll() {
+        scores.clear()
+    }
+
+    fun isEmpty(): Boolean {
+        return scores.isEmpty()
+    }
+}

app/src/main/java/me/zobrist/tichucounter/Round.kt

@@ -0,0 +1,36 @@
+package me.zobrist.tichucounter
+
+class Round() {
+    var scoreA: Int = 0
+    var scoreB: Int = 0
+
+    constructor(score: Int, isScoreA: Boolean) : this() {
+        if (isScoreA) {
+            scoreA = score
+            scoreB = calculateOtherScore(scoreA)
+        } else {
+            scoreB = score
+            scoreA = calculateOtherScore(scoreB)
+        }
+    }
+
+    constructor(scoreA: Int, scoreB: Int) : this() {
+        this.scoreA = scoreA
+        this.scoreB = scoreB
+    }
+
+    private fun calculateOtherScore(score: Int): Int {
+        if (isMultipleOf100(score)) {
+            return 0
+        }
+        return 100 - (score % 100)
+    }
+
+    private fun isMultipleOf100(score: Int): Boolean {
+        return (score / 100) >= 1 && (score % 100) == 0
+    }
+
+    fun isValidRound(): Boolean {
+        return (scoreA % 5 == 0) && (scoreB % 5 == 0) && ((scoreA + scoreB) % 100 == 0)
+    }
+}