feat: added initial assert subcommand

DEVELOPMENT.md

@@ -1,3 +1,11 @@
+## Ad hoc testing
+
+Beyond the unit tests, ad hoc "integration testing" can be done by running via Gradle passing the intended command-line via `--args`, such as:
+
+```shell
+./gradlew run --args="assert fileExists build.gradle"
+```
+
 ## Creating a new release
 
 The Github Actions workflow `publish-release` will take of performing the release build, but the tag needs to be created with the release tasks shown below.

build.gradle

@@ -137,12 +137,13 @@ dependencies {
     implementation 'com.jayway.jsonpath:json-path:2.6.0'
     implementation 'org.apache.maven:maven-artifact:3.8.4'
 
-    testImplementation 'org.assertj:assertj-core:3.21.0'
+    testImplementation 'org.assertj:assertj-core:3.22.0'
     testImplementation 'org.junit.jupiter:junit-jupiter:5.8.2'
     testImplementation 'org.junit.jupiter:junit-jupiter-params:5.8.2'
-    testImplementation 'org.mockito:mockito-junit-jupiter:4.1.0'
+    testImplementation 'org.mockito:mockito-junit-jupiter:4.2.0'
     testImplementation 'org.mock-server:mockserver-junit-jupiter:5.11.2'
-    testImplementation 'com.github.stefanbirkner:system-lambda:1.2.0'
+    // https://github.com/stefanbirkner/system-lambda
+    testImplementation 'com.github.stefanbirkner:system-lambda:1.2.1'
 
     annotationProcessor "info.picocli:picocli-codegen:${picocliVersion}"
 }

src/main/java/me/itzg/helpers/McImageHelper.java

@@ -3,6 +3,7 @@
 import ch.qos.logback.classic.Level;
 import ch.qos.logback.classic.Logger;
 import me.itzg.helpers.asciify.Asciify;
+import me.itzg.helpers.assertcmd.AssertCommand;
 import me.itzg.helpers.get.GetCommand;
 import me.itzg.helpers.hash.HashCommand;
 import me.itzg.helpers.patch.PatchCommand;
@@ -19,6 +20,7 @@
 @Command(name = "mc-image-helper",
     subcommands = {
         Asciify.class,
+        AssertCommand.class,
         CompareVersionsCommand.class,
         GetCommand.class,
         HashCommand.class,

src/main/java/me/itzg/helpers/assertcmd/AssertCommand.java

@@ -0,0 +1,11 @@
+package me.itzg.helpers.assertcmd;
+
+import picocli.CommandLine.Command;
+
+@Command(name = "assert", description = "Provides assertion operators for verifying container setup",
+  subcommands = {
+    FileExists.class
+  }
+)
+public class AssertCommand {
+}

src/main/java/me/itzg/helpers/assertcmd/FileExists.java

@@ -0,0 +1,32 @@
+package me.itzg.helpers.assertcmd;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+import java.util.concurrent.Callable;
+import picocli.CommandLine.Command;
+import picocli.CommandLine.ExitCode;
+import picocli.CommandLine.Parameters;
+
+@Command(name = "fileExists")
+class FileExists implements Callable<Integer> {
+
+  @Parameters
+  List<Path> paths;
+
+  @Override
+  public Integer call() throws Exception {
+    boolean missing = false;
+
+    if (paths != null) {
+      for (Path path : paths) {
+        if (!Files.exists(path)) {
+          System.err.printf("%s does not exist%n", path);
+          missing = true;
+        }
+      }
+    }
+
+    return missing ? ExitCode.SOFTWARE : ExitCode.OK;
+  }
+}

src/test/java/me/itzg/helpers/assertcmd/FileExistsTest.java

@@ -0,0 +1,56 @@
+package me.itzg.helpers.assertcmd;
+
+import static com.github.stefanbirkner.systemlambda.SystemLambda.tapSystemErr;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+import picocli.CommandLine;
+
+class FileExistsTest {
+
+  @Test
+  void passesWhenAllExist(@TempDir Path tempDir) throws Exception {
+    final Path file1 = Files.createFile(tempDir.resolve("file1"));
+    final Path file2 = Files.createFile(tempDir.resolve("file2"));
+
+    final String errOut = tapSystemErr(() -> {
+      int exitCode = new CommandLine(new FileExists())
+          .execute(
+              file1.toString(),
+              file2.toString()
+          );
+
+      assertThat(exitCode).isEqualTo(0);
+    });
+
+    assertThat(errOut).isBlank();
+  }
+
+  @Test
+  void failsWhenSomeMissing(@TempDir Path tempDir) throws Exception {
+    final Path file1 = Files.createFile(tempDir.resolve("file1"));
+    final Path file2 = Files.createFile(tempDir.resolve("file2"));
+    final Path pathA = tempDir.resolve("fileA");
+    final Path fileB = tempDir.resolve("fileB");
+
+    final String errOut = tapSystemErr(() -> {
+      int exitCode = new CommandLine(new FileExists())
+          .execute(
+              file1.toString(),
+              pathA.toString(),
+              file2.toString(),
+              fileB.toString()
+          );
+
+      assertThat(exitCode).isEqualTo(1);
+    });
+
+    assertThat(errOut).contains(
+        "fileA does not exist",
+        "fileB does not exist"
+    );
+  }
+}