feat: take TestSelector into account

More information can be found at sbt/junit-interface#108

junit-interface/src/main/java/munit/internal/junitinterface/JUnitRunner.java

@@ -11,8 +11,13 @@
 
 import sbt.testing.Runner;
 import sbt.testing.Task;
+import sbt.testing.Selector;
+import sbt.testing.TestSelector;
 import sbt.testing.TaskDef;
 
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
 final class JUnitRunner implements Runner {
   private final String[] args;
   private final String[] remoteArgs;
@@ -127,7 +132,8 @@ public Task[] tasks(TaskDef[] taskDefs) {
     for (int i = 0; i < length; i++) {
       TaskDef taskDef = taskDefs[i];
       if (shouldRun(computer, taskDef)) {
-        tasks.add(new JUnitTask(this, settings, taskDef, computer));
+        RunSettings alteredSettings = alterRunSettings(this.settings, taskDef.selectors());
+        tasks.add(new JUnitTask(this, alteredSettings, taskDef, computer));
       }
     }
     return tasks.toArray(new Task[0]);
@@ -153,6 +159,35 @@ private RunListener createRunListener(String runListenerClassName) {
     } else return null;
   }
 
+  /**
+   * Alter default RunSettings depending on the passed selectors. If selectors contains only
+   * elements of type TestSelector, then default settings are altered to include only test names
+   * from these selectors. This allows to run particular test cases within given test class.
+   * testFilter is treated as a regular expression, hence joining is done via '|'.
+   */
+  private RunSettings alterRunSettings(RunSettings defaultSettings, Selector[] selectors) {
+    List<TestSelector> testSelectors =
+        Arrays.stream(selectors)
+            .flatMap(
+                selector -> {
+                  return selector instanceof TestSelector
+                      ? Stream.of((TestSelector) selector)
+                      : Stream.empty();
+                })
+            .collect(Collectors.toList());
+    if (testSelectors.size() == selectors.length) {
+      String testFilter =
+          testSelectors.stream().map(TestSelector::testName).collect(Collectors.joining("|"));
+      // if already provided testFilter is not empty add to it | (regex or operator)
+      String currentFilter =
+          defaultSettings.testFilter.length() > 0 ? defaultSettings.testFilter + "|" : "";
+      String newFilter = currentFilter + testFilter;
+      return defaultSettings.withTestFilter(newFilter);
+    }
+
+    return defaultSettings;
+  }
+
   @Override
   public String done() {
     // Can't simply return the summary due to https://github.com/sbt/sbt/issues/3510

junit-interface/src/main/java/munit/internal/junitinterface/RunSettings.java

@@ -78,6 +78,28 @@ class RunSettings implements Settings {
     this.trimStackTraces = trimStackTraces;
   }
 
+  public RunSettings withTestFilter(String newTestFilter) {
+    String ignoreRunners = String.join(",", this.ignoreRunners);
+    return new RunSettings(
+        this.color,
+        this.decodeScalaNames,
+        this.verbose,
+        this.useSbtLoggers,
+        this.useBufferedLoggers,
+        this.trimStackTraces,
+        this.summary,
+        this.logAssert,
+        ignoreRunners,
+        this.logExceptionClass,
+        this.sysprops,
+        this.globPatterns,
+        this.includeCategories,
+        this.excludeCategories,
+        this.includeTags,
+        this.excludeTags,
+        newTestFilter);
+  }
+
   String decodeName(String name) {
     return decodeScalaNames ? decodeScalaName(name) : name;
   }

tests/jvm/src/test/scala/munit/TestSelectorSuite.scala

@@ -0,0 +1,122 @@
+package munit
+
+import sbt.testing.Event
+import sbt.testing.EventHandler
+import sbt.testing.Selector
+import sbt.testing.Status
+import sbt.testing.SuiteSelector
+import sbt.testing.TaskDef
+import sbt.testing.TestSelector
+import scala.collection.mutable
+import sbt.testing.Runner
+
+/**
+ * Dummy test suite which is needed by TestSelectorSuite
+ */
+class MyTestSuite extends FunSuite {
+
+  test("testFoo") {
+    assert(true, "Test should pass")
+  }
+
+  test("testBar") {
+    assert(true, "Test should pass")
+  }
+}
+
+/**
+ * Check if TestSelector's are correctly handled by Munit.
+ * Execute prepared TaskDef's using manually created instances of sbt.testing.{Framework and Runner}.
+ */
+class TestSelectorSuite extends FunSuite {
+  val framework = new Framework();
+  val runner: Runner = framework.runner(
+    Array.empty,
+    Array.empty,
+    this.getClass().getClassLoader()
+  );
+
+  val fingerprint = framework.munitFingerprint
+
+  /**
+   * Reference to the collection which will contain fully qualified names of executed tests.
+   * Only after finished execution it's safe to convert this mutable collection to immutable one.
+   */
+  private def getEventHandler(): (mutable.ListBuffer[String], EventHandler) = {
+    val executedItems = new mutable.ListBuffer[String]
+    val eventHandler = new EventHandler {
+      override def handle(event: Event) =
+        if (event.status() == Status.Success) {
+          executedItems += event.fullyQualifiedName()
+        }
+    }
+    (executedItems, eventHandler)
+  }
+
+  private def getTaskDefs(selectors: Array[Selector]): Array[TaskDef] = {
+    Array(
+      new TaskDef("munit.MyTestSuite", fingerprint, false, selectors)
+    )
+  }
+
+  test("runAllViaSuiteSelector") {
+    val selectors = Array[Selector](
+      new SuiteSelector
+    )
+    val taskDefs = Array(
+      new TaskDef("munit.MyTestSuite", fingerprint, false, selectors)
+    )
+
+    val tasks = runner.tasks(taskDefs)
+    assertEquals(tasks.size, 1)
+    val task = tasks(0)
+
+    val (executedItems, eventHandler) = getEventHandler()
+
+    task.execute(eventHandler, Nil.toArray)
+    assertEquals(
+      executedItems.toSet,
+      Set("munit.MyTestSuite.testBar", "munit.MyTestSuite.testFoo")
+    )
+  }
+
+  test("runAllViaTestSelectors") {
+    val selectors = Array[Selector](
+      new TestSelector("testFoo"),
+      new TestSelector("testBar")
+    )
+    val taskDefs = getTaskDefs(selectors)
+
+    val tasks = runner.tasks(taskDefs)
+    assertEquals(tasks.size, 1)
+    val task = tasks(0)
+
+    val (executedItems, eventHandler) = getEventHandler()
+
+    task.execute(eventHandler, Nil.toArray)
+    assertEquals(
+      executedItems.toSet,
+      Set("munit.MyTestSuite.testBar", "munit.MyTestSuite.testFoo")
+    )
+  }
+
+  test("runOnlyOne") {
+    val selectors = Array[Selector](
+      new TestSelector("testFoo")
+    )
+    val taskDefs = getTaskDefs(selectors)
+
+    val tasks = runner.tasks(taskDefs)
+    assertEquals(tasks.size, 1)
+    val task = tasks(0)
+
+    val (executedItems, eventHandler) = getEventHandler()
+
+    task.execute(eventHandler, Nil.toArray)
+    assertEquals(
+      executedItems.toSet,
+      Set("munit.MyTestSuite.testFoo")
+    )
+
+  }
+}