From 97ed27f846f3e53dc127c577e6667f5faf6a814b Mon Sep 17 00:00:00 2001
From: Avahe Kellenberger <avahe@protonmail.ch>
Date: Mon, 9 Mar 2020 10:44:02 -0400
Subject: [PATCH] Add `leaves` option to show modules that do not have
 dependencies

---
 README.md   |  16 ++++++++
 bin/cli.js  | 116 ++++++++++++++++++++++++++++++----------------------
 lib/api.js  |  10 +++++
 test/api.js |   9 ++++
 4 files changed, 101 insertions(+), 50 deletions(-)

diff --git a/README.md b/README.md
index 49e4ce14..5b0e95ea 100644
--- a/README.md
+++ b/README.md
@@ -151,6 +151,18 @@ madge('path/to/app.js').then((res) => {
 });
 ```
 
+#### .leaves()
+
+> Return an `Array` of all modules that have no dependencies.
+
+```javascript
+const madge = require('madge');
+
+madge('path/to/app.js').then((res) => {
+	console.log(res.leaves());
+});
+```
+
 #### .dot()
 
 > Returns a `Promise` resolved with a DOT representation of the module dependency graph.
@@ -304,6 +316,10 @@ $ madge --depends wheels.js path/src/app.js
 $ madge --orphans path/src/
 ```
 
+```sh
+$ madge --leaves path/src/
+```
+
 > Excluding modules
 
 ```sh
diff --git a/bin/cli.js b/bin/cli.js
index e87d888f..ace5da8a 100755
--- a/bin/cli.js
+++ b/bin/cli.js
@@ -22,6 +22,7 @@ program
 	.option('-i, --image <file>', 'write graph to file as an image')
 	.option('-l, --layout <name>', 'layout engine to use for graph (dot/neato/fdp/sfdp/twopi/circo)')
 	.option('--orphans', 'show modules that no one is depending on')
+	.option('--leaves', 'show modules that have no dependencies')
 	.option('--dot', 'show graph using the DOT language')
 	.option('--extensions <list>', 'comma separated string of valid file extensions')
 	.option('--require-config <file>', 'path to RequireJS config')
@@ -172,56 +173,9 @@ new Promise((resolve, reject) => {
 			output.getResultSummary(res, startTime);
 		}
 
-		if (program.summary) {
-			output.summary(res.obj(), {
-				json: program.json
-			});
-
-			return res;
-		}
-
-		if (program.depends) {
-			output.modules(res.depends(program.depends), {
-				json: program.json
-			});
-
-			return res;
-		}
-
-		if (program.orphans) {
-			output.modules(res.orphans(), {
-				json: program.json
-			});
-
-			return res;
-		}
-
-		if (program.circular) {
-			const circular = res.circular();
-
-			output.circular(spinner, res, circular, {
-				json: program.json
-			});
-
-			if (circular.length) {
-				exitCode = 1;
-			}
-
-			return res;
-		}
-
-		if (program.image) {
-			return res.image(program.image).then((imagePath) => {
-				spinner.succeed(`${chalk.bold('Image created at')} ${chalk.cyan.bold(imagePath)}`);
-				return res;
-			});
-		}
-
-		if (program.dot) {
-			return res.dot().then((output) => {
-				process.stdout.write(output);
-				return res;
-			});
+		const result = createOutputFromOptions(program, res);
+		if (result !== undefined) {
+			return result;
 		}
 
 		output.list(res.obj(), {
@@ -246,3 +200,65 @@ new Promise((resolve, reject) => {
 		console.log('\n%s %s\n', chalk.red('✖'), err.stack);
 		process.exit(1);
 	});
+
+function createOutputFromOptions(program, res) {
+	if (program.summary) {
+		output.summary(res.obj(), {
+			json: program.json
+		});
+
+		return res;
+	}
+
+	if (program.depends) {
+		output.modules(res.depends(program.depends), {
+			json: program.json
+		});
+
+		return res;
+	}
+
+	if (program.orphans) {
+		output.modules(res.orphans(), {
+			json: program.json
+		});
+
+		return res;
+	}
+
+	if (program.leaves) {
+		output.modules(res.leaves(), {
+			json: program.json
+		});
+
+		return res;
+	}
+
+	if (program.circular) {
+		const circular = res.circular();
+
+		output.circular(spinner, res, circular, {
+			json: program.json
+		});
+
+		if (circular.length) {
+			exitCode = 1;
+		}
+
+		return res;
+	}
+
+	if (program.image) {
+		return res.image(program.image).then((imagePath) => {
+			spinner.succeed(`${chalk.bold('Image created at')} ${chalk.cyan.bold(imagePath)}`);
+			return res;
+		});
+	}
+
+	if (program.dot) {
+		return res.dot().then((output) => {
+			process.stdout.write(output);
+			return res;
+		});
+	}
+}
diff --git a/lib/api.js b/lib/api.js
index 60ed0393..2d1cc5b2 100644
--- a/lib/api.js
+++ b/lib/api.js
@@ -129,6 +129,16 @@ class Madge {
 			.filter((dep) => !map[dep]);
 	}
 
+	/**
+	* Return a list of modules that have no dependencies.
+	* @api public
+	* @return {Array}
+	*/
+	leaves() {
+		const tree = this.obj();
+		return Object.keys(tree).filter((key) => !tree[key].length);
+	}
+
 	/**
 	 * Return the module dependency graph as DOT output.
 	 * @api public
diff --git a/test/api.js b/test/api.js
index 0a96edca..697486eb 100644
--- a/test/api.js
+++ b/test/api.js
@@ -235,6 +235,15 @@ describe('API', () => {
 		});
 	});
 
+	describe('leaves()', () => {
+		it('returns modules that have no dependencies', (done) => {
+			madge(__dirname + '/cjs/normal').then((res) => {
+				res.leaves().should.eql(['d.js']);
+				done();
+			}).catch(done);
+		});
+	});
+
 	describe('svg()', () => {
 		it('returns a promise resolved with XML SVG output in a Buffer', (done) => {
 			madge(__dirname + '/cjs/b.js')