README fixes and LinesSource

Enables JUnit parameterised tests.

Author: mpetuska

README.md

@@ -40,10 +40,10 @@ Here's the overview of your daily routine while solving AoC puzzles:
 1. Open `./calendar/dayX` directory for the day you're solving.
 2. Paste your input for part1 into `part1.txt`.
 3. Open `DayX.kt` file and implement your solution in `part1` method and return your answer.
-4. Check your solution for part1 by running `./gradlew test --tests='dayX.DayX#part1'`
-5. Paste your input for part2 into `part2.txt`.
+4. Check your solution for part1 by running `./gradlew test --tests='dayX.DayX.part1'`
+5. Paste your input for part2 into `part2.txt` (only if it's different frm `part1`, otherwise `part1.txt` will be used.
 6. Open `DayX.kt` file and implement your solution in `part2` method and return your answer.
-7. Check your solution for part2 by running `./gradlew test --tests='dayX.DayX#part2'`
+7. Check your solution for part2 by running `./gradlew test --tests='dayX.DayX.part2'`
 8. Check both your solutions by running `./gradlew test --tests='dayX.DayX'`
 9. Submit your answers to [AoC](https://adventofcode.com)
 10. Clean up inputs by running `./gradlew cleanInputs`

build.gradle.kts

@@ -13,6 +13,7 @@ repositories {
 
 dependencies {
     implementation(kotlin("test-junit5"))
+    implementation("org.junit.jupiter:junit-jupiter-params")
 }
 
 sourceSets {

src/main/kotlin/Day.kt

@@ -1,8 +1,13 @@
 import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.extension.ExtensionContext
+import org.junit.jupiter.params.ParameterizedTest
+import org.junit.jupiter.params.provider.Arguments
+import org.junit.jupiter.params.provider.ArgumentsProvider
 import java.awt.Toolkit
 import java.awt.datatransfer.StringSelection
 import java.io.File
 import java.util.*
+import java.util.stream.Stream
 import kotlin.time.ExperimentalTime
 import kotlin.time.measureTimedValue
 
@@ -42,9 +47,36 @@ abstract class Day {
         Toolkit.getDefaultToolkit().systemClipboard.setContents(StringSelection(data), null)
     }
 
+
     @Test
     fun part1(): Unit = solve("part1.txt", null, ::part1)
 
     @Test
     fun part2(): Unit = solve("part2.txt", "part1.txt", ::part2)
+
+    /**
+     * [Lines] provider for JUnit [ParameterizedTest].
+     * It reads the file named `{test_method_name}.txt` placed in the same directory as the test class.
+     *
+     * Usage:
+     * ```kotlin
+     * @ParameterizedTest
+     * @ArgumentsSource(LinesSource::class)
+     * fun part1(input: Lines) {}
+     * ```
+     */
+    class LinesSource : ArgumentsProvider {
+        private fun Class<*>.readInput(inputFileName: String) =
+            this::class.java.getResource(inputFileName)?.toURI()?.let(::File)?.takeIf { it.length() > 0 }
+
+        override fun provideArguments(context: ExtensionContext): Stream<out Arguments> {
+            val clazz = context.testClass.get()
+            val method = context.testMethod.get()
+            val input = clazz.readInput("${method.name}.txt")
+                ?: clazz.readInput("${method.name}.txt".replace("2", "1"))
+                ?: error("${method.name}.txt not found")
+            return Stream.of(Arguments.of(input.readLines()))
+        }
+
+    }
 }