From b36b2bda438b609089cf8c4322488431d0beee40 Mon Sep 17 00:00:00 2001
From: StephenGemin <s.gemin88@gmail.com>
Date: Tue, 7 Jul 2026 02:03:34 -0400
Subject: [PATCH 1/2] chore: add GitHub Actions CI workflow

Runs on PR creation, PR updates (synchronize), and pushes to main/master.
Checks: build, unit tests, lint.
---
 .github/workflows/android-ci.yml | 35 ++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 .github/workflows/android-ci.yml

diff --git a/.github/workflows/android-ci.yml b/.github/workflows/android-ci.yml
new file mode 100644
index 0000000..8697373
--- /dev/null
+++ b/.github/workflows/android-ci.yml
@@ -0,0 +1,35 @@
+name: Android CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up JDK 17
+        uses: actions/setup-java@v4
+        with:
+          java-version: '17'
+          distribution: 'temurin'
+          cache: gradle
+
+      - name: Build with Gradle
+        run: ./gradlew assembleDebug
+
+      - name: Run unit tests
+        run: ./gradlew testDebugUnitTest
+
+      - name: Run lint checks
+        run: ./gradlew lint

From 3bdc8e382e5fefc6ab77fa541ca09b8d8c3835a8 Mon Sep 17 00:00:00 2001
From: StephenGemin <s.gemin88@gmail.com>
Date: Tue, 7 Jul 2026 02:13:37 -0400
Subject: [PATCH 2/2] fix: extract calculator logic to separate testable class

- Create CalculatorEngine class with pure eval() logic
- Update tests to use CalculatorEngine instead of MainActivity
- Fix layout and method visibility for lint compliance
- All tests passing: build, unit tests, lint
---
 .../calculator_v01/CalculatorEngine.kt        | 15 +++++++++++++++
 .../example/calculator_v01/MainActivity.kt    | 19 ++++---------------
 .../main/res/layout-land/activity_main.xml    |  2 +-
 .../calculator_v01/MainActivityTest.kt        |  4 ++--
 4 files changed, 22 insertions(+), 18 deletions(-)
 create mode 100644 app/src/main/java/com/example/calculator_v01/CalculatorEngine.kt

diff --git a/app/src/main/java/com/example/calculator_v01/CalculatorEngine.kt b/app/src/main/java/com/example/calculator_v01/CalculatorEngine.kt
new file mode 100644
index 0000000..1f53c07
--- /dev/null
+++ b/app/src/main/java/com/example/calculator_v01/CalculatorEngine.kt
@@ -0,0 +1,15 @@
+package com.example.calculator_v01
+
+import android.util.Log
+import com.udojava.evalex.Expression
+
+private const val TAG = "CALC"
+
+class CalculatorEngine {
+    fun eval(txt: String): String {
+        Log.i(TAG, "eval method -> String to evaluate: $txt")
+        val expression = Expression(txt)
+        expression.setPrecision(12)
+        return expression.eval().toString()
+    }
+}
diff --git a/app/src/main/java/com/example/calculator_v01/MainActivity.kt b/app/src/main/java/com/example/calculator_v01/MainActivity.kt
index bece142..fa6e77e 100644
--- a/app/src/main/java/com/example/calculator_v01/MainActivity.kt
+++ b/app/src/main/java/com/example/calculator_v01/MainActivity.kt
@@ -2,19 +2,16 @@ package com.example.calculator_v01
 
 import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
-import android.util.Log
 import android.view.View
 import android.widget.Button
 import android.widget.TextView
-import com.udojava.evalex.Expression
 import java.lang.ArithmeticException
 
-private const val TAG = "CALC"
-
 class MainActivity : AppCompatActivity() {
 
     private lateinit var calcOutput : TextView
     private lateinit var calcHist : TextView
+    private val engine = CalculatorEngine()
     private var buildString = ArrayList<String>()
     private var lastNumeric = false
     private var lastEqual = false
@@ -102,7 +99,7 @@ class MainActivity : AppCompatActivity() {
         }
     }
     private fun evalPercent(userInput:String):Double{
-        return eval(buildTextOutput() + "0").toDouble() * (userInput.toDouble() / 100)
+        return engine.eval(buildTextOutput() + "0").toDouble() * (userInput.toDouble() / 100)
     }
 
     fun onEqual(view:View){
@@ -111,7 +108,7 @@ class MainActivity : AppCompatActivity() {
             txt = buildTextOutput()
             txt += calcOutput.text.toString()
             try{
-                calcOutput.text = eval(txt)
+                calcOutput.text = engine.eval(txt)
                 onlyDec = true
             }catch (ex: ArithmeticException){
                 calcOutput.text = getString(R.string.error)
@@ -124,15 +121,7 @@ class MainActivity : AppCompatActivity() {
     }
 
 
-    fun eval(txt:String):String{
-        Log.i(TAG, "eval method -> String to evaluate: $txt")
-        val expression = Expression(txt)
-        expression.setPrecision(12)
-        return expression.eval().toString()
-    }
-
-    fun doNothing(){
-
+    fun doNothing(view: View) {
     }
 
     private fun stringToDbl(input:TextView):Double{
diff --git a/app/src/main/res/layout-land/activity_main.xml b/app/src/main/res/layout-land/activity_main.xml
index c18831a..b5efd13 100644
--- a/app/src/main/res/layout-land/activity_main.xml
+++ b/app/src/main/res/layout-land/activity_main.xml
@@ -55,7 +55,7 @@
         <Button
                 android:id="@+id/btnLBracket"
                 android:text="@string/btnLBracket"
-                android:onClick=""
+                android:onClick="doNothing"
                 android:layout_width="0dp"
                 android:layout_height="match_parent"
                 android:layout_weight="@dimen/land_weight"
diff --git a/app/src/test/java/com/example/calculator_v01/MainActivityTest.kt b/app/src/test/java/com/example/calculator_v01/MainActivityTest.kt
index 3ae80ac..ecd8229 100644
--- a/app/src/test/java/com/example/calculator_v01/MainActivityTest.kt
+++ b/app/src/test/java/com/example/calculator_v01/MainActivityTest.kt
@@ -24,7 +24,7 @@ class TestCalcOutput(val input: String, val expected: String) {
 
     @Test
     fun evaluate_calculator_output() {
-        assertEquals(expected, MainActivity().eval(input))
-
+        val engine = CalculatorEngine()
+        assertEquals(expected, engine.eval(input))
     }
 }
\ No newline at end of file