feat: Implement action execution system

Actions can be added to the app.yml file. Each action is simply a command that will get executed when the given action is activated with `jpm do <action>`. Commands can contain special "variables" that will get replaced just before execution. The most important is `{{deps}}` which will result in the full classpath to all dependencies defined in the app.yml being inserted in the command. The remaining one all have to do with making it easier to create os-specific paths (so commands will work both on WIndows and Linux/Mac).

Author: Copilot

.github/copilot-instructions.md

@@ -84,7 +84,7 @@ Always manually validate jpm functionality after making changes:
 
 ### Important Files
 - `pom.xml` - Maven configuration with Spotless formatting, Shade plugin, Appassembler
-- `app.yml` - Example dependency configuration (also created by jpm install)
+- `app.yml` - jpm's actual runtime dependencies and actions (NOT an example file). Dependencies should be kept up-to-date with the (non-test) dependencies in pom.xml
 - `RELEASE.md` - Release process documentation
 - `.gitignore` - Excludes target/, deps/, IDE files
 

.github/workflows/ci.yml

@@ -18,7 +18,10 @@ on:
 jobs:
   build:
 
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest]
 
     steps:
     - uses: actions/checkout@v5

README.md

@@ -89,6 +89,76 @@ to get the required dependencies to run the code.
 _NB: We could have used `jpm copy` instead of `jpm install` to copy the dependencies but that would not have created
 the `app.yml` file._
 
+## Actions
+
+The `app.yml` file doesn't just track dependencies - it can also define custom actions that can be executed with the `jpm do` command or through convenient alias commands.
+
+### Defining Actions
+
+Actions are defined in the `actions` section of your `app.yml` file:
+
+```yaml
+dependencies:
+  com.github.lalyos:jfiglet:0.0.9
+
+actions:
+  build: "javac -cp {{deps}} *.java"
+  run: "java -cp {{deps}} HelloWorld"
+  test: "java -cp {{deps}} TestRunner"
+  clean: "rm -f *.class"
+```
+
+### Executing Actions
+
+You can execute actions using the `jpm do` command:
+
+```shell
+$ jpm do build
+$ jpm do run
+$ jpm do --list    # Lists all available actions
+```
+
+Or use the convenient alias commands:
+
+```shell
+$ jpm build        # Executes the 'build' action
+$ jpm run          # Executes the 'run' action
+$ jpm test         # Executes the 'test' action
+$ jpm clean        # Executes the 'clean' action
+```
+
+Alias commands can accept additional arguments that will be passed through to the underlying action:
+
+```shell
+$ jpm run --verbose debug    # Passes '--verbose debug' to the run action
+```
+
+### Variable Substitution
+
+Actions support several variable substitution features for cross-platform compatibility:
+
+- **`{{deps}}`** - Replaced with the full classpath of all dependencies
+- **`{/}`** - Replaced with the file separator (`\` on Windows, `/` on Linux/Mac)
+- **`{:}`** - Replaced with the path separator (`;` on Windows, `:` on Linux/Mac)
+- **`{~}`** - Replaced with the user's home directory (The actual path on Windows, `~` on Linux/Mac)
+- **`{./path/to/file}`** - Converts relative paths to platform-specific format
+- **`{./libs:./ext:~/usrlibs}`** - Converts entire class paths to platform-specific format
+
+Example with cross-platform compatibility:
+
+```yaml
+actions:
+  build: "javac -cp {{deps}} -d {./target/classes} src{/}*.java"
+  run: "java -cp {{deps}}{:}{./target/classes} Main"
+  test: "java -cp {{deps}}{:}{./target/classes} org.junit.runner.JUnitCore TestSuite"
+```
+
+NB: The `{{deps}}` variable substitution is only performed when needed - if your action doesn't contain `{{deps}}`, jpm won't resolve the classpath, making execution faster for simple actions that don't require dependencies.
+
+NB2: These actions are just a very simple convenience feature. For a much more full-featured cross-platform action runner I recommend taking a look at:
+
+ - [Just](https://github.com/casey/just) - Just a command runner
+
 ## Installation
 
 For now the simplest way to install `jpm` is to use [JBang](https://www.jbang.dev/download/):
@@ -132,8 +202,8 @@ Commands:
                 dependencies to the target directory while at the same time
                 removing any artifacts that are no longer needed (ie the ones
                 that are not mentioned in the app.yml file). If no artifacts
-                are passed the app.yml file will be left untouched and only
-                the existing dependencies in the file will be copied.
+                are passed the app.yml file will be left untouched and only the
+                existing dependencies in the file will be copied.
 
               Example:
                 jpm install org.apache.httpcomponents:httpclient:4.5.14
@@ -145,6 +215,18 @@ Commands:
 
               Example:
                 jpm path org.apache.httpcomponents:httpclient:4.5.14
+
+  do          Executes an action command defined in the app.yml file. Actions
+                can use variable substitution for classpath.
+
+              Example:
+                jpm do build
+                jpm do test
+
+  clean       Executes the 'clean' action as defined in the app.yml file.
+  build       Executes the 'build' action as defined in the app.yml file.
+  run         Executes the 'run' action as defined in the app.yml file.
+  test        Executes the 'test' action as defined in the app.yml file.
 ```
 
 ## Development

app.yml

@@ -1,10 +1,15 @@
 dependencies:
-  eu.maveniverse.maven.mima:context: "2.4.15"
-  eu.maveniverse.maven.mima.runtime:standalone-static: "2.4.15"
-  info.picocli:picocli: "4.7.6"
-  org.yaml:snakeyaml: "2.3"
-  org.jline:jline-console-ui: "3.29.0"
-  org.jline:jline-terminal-jni: "3.29.0"
-  org.slf4j:slf4j-api: "2.0.13"
-  org.slf4j:slf4j-log4j12: "2.0.13"
-  org.slf4j:slf4j-simple: "2.0.13"
+  eu.maveniverse.maven.mima:context: "2.4.33"
+  eu.maveniverse.maven.mima.runtime:standalone-static: "2.4.33"
+  info.picocli:picocli: "4.7.7"
+  org.yaml:snakeyaml: "2.4"
+  org.jline:jline-console-ui: "3.30.5"
+  org.jline:jline-terminal-jni: "3.30.5"
+  org.slf4j:slf4j-api: "2.0.17"
+  org.slf4j:slf4j-simple: "2.0.17"
+
+actions:
+  clean: ".{/}mvnw clean"
+  build: ".{/}mvnw spotless:apply package -DskipTests"
+  run: "{./target/binary/bin/jpm}"
+  test: ".{/}mvnw test"

pom.xml

@@ -39,6 +39,9 @@
         <version.slf4j>2.0.17</version.slf4j>
         <version.spotless>2.46.1</version.spotless>
         <version.google-java-format>1.22.0</version.google-java-format>
+        <version.junit>5.11.4</version.junit>
+        <version.mockito>5.15.2</version.mockito>
+        <version.assertj>3.26.3</version.assertj>
     </properties>
 
     <dependencies>
@@ -82,6 +85,32 @@
             <artifactId>slf4j-simple</artifactId>
             <version>${version.slf4j}</version>
         </dependency>
+        
+        <!-- Test dependencies -->
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>${version.junit}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <version>${version.mockito}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-junit-jupiter</artifactId>
+            <version>${version.mockito}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${version.assertj}</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>
@@ -97,6 +126,11 @@
                     <artifactId>maven-compiler-plugin</artifactId>
                     <version>3.14.0</version>
                 </plugin>
+                <plugin>
+                    <groupId>org.apache.maven.plugins</groupId>
+                    <artifactId>maven-surefire-plugin</artifactId>
+                    <version>3.5.2</version>
+                </plugin>
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-jar-plugin</artifactId>

src/main/java/org/codejive/jpm/Jpm.java

@@ -12,10 +12,12 @@
 public class Jpm {
     private final Path directory;
     private final boolean noLinks;
+    private final boolean verbose;
 
-    private Jpm(Path directory, boolean noLinks) {
+    private Jpm(Path directory, boolean noLinks, boolean verbose) {
         this.directory = directory;
         this.noLinks = noLinks;
+        this.verbose = verbose;
     }
 
     /**
@@ -31,6 +33,7 @@ public static Builder builder() {
     public static class Builder {
         private Path directory;
         private boolean noLinks;
+        private boolean verbose;
 
         private Builder() {}
 
@@ -56,13 +59,24 @@ public Builder noLinks(boolean noLinks) {
             return this;
         }
 
+        /**
+         * Set whether to enable verbose output or not.
+         *
+         * @param verbose Whether to enable verbose output or not.
+         * @return The builder instance for chaining.
+         */
+        public Builder verbose(boolean verbose) {
+            this.verbose = verbose;
+            return this;
+        }
+
         /**
          * Builds the {@link Jpm} instance.
          *
          * @return A {@link Jpm} instance.
          */
         public Jpm build() {
-            return new Jpm(directory, noLinks);
+            return new Jpm(directory, noLinks, verbose);
         }
     }
 
@@ -167,6 +181,49 @@ private static String[] getArtifacts(String[] artifactNames, AppInfo appInfo) {
         return deps;
     }
 
+    /**
+     * Executes an action defined in app.yml file.
+     *
+     * @param actionName The name of the action to execute (null to list actions)
+     * @return An integer containing the exit result of the action
+     * @throws IllegalArgumentException If the action name is not provided or not found
+     * @throws IOException If an error occurred during the operation
+     * @throws DependencyResolutionException If an error occurred during dependency resolution
+     * @throws InterruptedException If the action execution was interrupted
+     */
+    public int executeAction(String actionName, List<String> args)
+            throws IOException, DependencyResolutionException, InterruptedException {
+        AppInfo appInfo = AppInfo.read();
+
+        // Get the action command
+        String command = appInfo.getAction(actionName);
+        if (command == null) {
+            throw new IllegalArgumentException(
+                    "Action '"
+                            + actionName
+                            + "' not found in app.yml. Use --list to see available actions.");
+        }
+
+        // Get the classpath for variable substitution only if needed
+        List<Path> classpath = Collections.emptyList();
+        if (command.contains("{{deps}}")) {
+            classpath = this.path(new String[0]); // Empty array means use dependencies from app.yml
+        }
+
+        return ScriptUtils.executeScript(command, args, classpath, true);
+    }
+
+    /**
+     * Returns a list of available action names defined in the app.yml file.
+     *
+     * @return A list of available action names
+     * @throws IOException If an error occurred during the operation
+     */
+    public List<String> listActions() throws IOException {
+        AppInfo appInfo = AppInfo.read();
+        return new ArrayList<>(appInfo.getActionNames());
+    }
+
     private static boolean isWindows() {
         String os =
                 System.getProperty("os.name")