add tests

Author: HT154

pkl-gradle/src/main/java/org/pkl/gradle/ExternalReader.java

@@ -16,12 +16,11 @@
 package org.pkl.gradle;
 
 import java.io.Serializable;
+import java.util.Collections;
 import java.util.List;
-import org.pkl.core.util.Nullable;
 
-public record ExternalReader(String executable, @Nullable List<String> arguments)
-    implements Serializable {
+public record ExternalReader(String executable, List<String> arguments) implements Serializable {
   public ExternalReader(String executable) {
-    this(executable, null);
+    this(executable, Collections.emptyList());
   }
 }

pkl-gradle/src/main/java/org/pkl/gradle/spec/BasePklSpec.java

@@ -60,7 +60,7 @@ public interface BasePklSpec {
   ListProperty<String> getHttpNoProxy();
 
   MapProperty<URI, URI> getHttpRewrites();
-  
+
   MapProperty<String, ExternalReader> getExternalModuleReaders();
 
   MapProperty<String, ExternalReader> getExternalResourceReaders();

pkl-gradle/src/main/java/org/pkl/gradle/task/BasePklTask.java

@@ -40,7 +40,6 @@
 import org.gradle.api.tasks.InputFile;
 import org.gradle.api.tasks.InputFiles;
 import org.gradle.api.tasks.Internal;
-import org.gradle.api.tasks.Nested;
 import org.gradle.api.tasks.Optional;
 import org.gradle.api.tasks.TaskAction;
 import org.pkl.commons.cli.CliBaseOptions;
@@ -148,13 +147,11 @@ public Provider<String> getEvalRootDirPath() {
   @Input
   @Optional
   public abstract MapProperty<URI, URI> getHttpRewrites();
-  
+
   @Input
-  @Optional
   public abstract MapProperty<String, ExternalReader> getExternalModuleReaders();
 
   @Input
-  @Optional
   public abstract MapProperty<String, ExternalReader> getExternalResourceReaders();
 
   /**

pkl-gradle/src/test/kotlin/org/pkl/gradle/EvaluatorsTest.kt

@@ -896,6 +896,46 @@ class EvaluatorsTest : AbstractTest() {
     assertThat(result5.task(":evalTestGatherImports")).isNull()
   }
 
+  @Test
+  fun `external module reader`() {
+    writePklFile("import \"foo:test.pkl\"")
+    writeBuildFile(
+      "json",
+      additionalContents =
+        """
+      allowedModules = ["foo:", "file:", "repl:text"]
+      externalModuleReaders = ["foo": new org.pkl.gradle.ExternalReader("echo")]
+    """
+          .trimIndent(),
+    )
+
+    // this is not actually a valid external reader, so we expect this to fail
+    // this test is just asserting that Pkl is configured to use the external process
+    // and that it does attempt to do so
+    val result = runTask("evalTest", true)
+    assertThat(result.output).contains("IOException: Stream closed")
+  }
+
+  @Test
+  fun `external resource reader`() {
+    writePklFile("result = read(\"foo:test\")")
+    writeBuildFile(
+      "json",
+      additionalContents =
+        """
+      allowedResources = ["foo:", "prop:"]
+      externalResourceReaders = ["foo": new org.pkl.gradle.ExternalReader("echo")]
+    """
+          .trimIndent(),
+    )
+
+    // this is not actually a valid external reader, so we expect this to fail
+    // this test is just asserting that Pkl is configured to use the external process
+    // and that it does attempt to do so
+    val result = runTask("evalTest", true)
+    assertThat(result.output).contains("IOException: Stream closed")
+  }
+
   private fun writeBuildFile(
     // don't use `org.pkl.core.OutputFormat`
     // because test compile class path doesn't contain pkl-core