fix: Handle dependency cycles gracefully

The toArchy-function now has a cycle-checker that adds a special
"cycle"-node to the tree, when one has been detected

src/index.js

@@ -23,7 +23,7 @@ function analyze (cwd, options = {}) {
     .then(function (tree) {
       return archy({
         label: `size: ${tree.rootPackage.stats.totalBlockSize() / 1024}k... with-dependencies: ${tree.rootPackage.totalStats().totalBlockSize() / 1024}k`,
-        nodes: toArchy(tree.prod, options.depth)
+        nodes: toArchy(tree.prod, options.depth, [])
       })
     })
 }
@@ -33,15 +33,27 @@ function analyze (cwd, options = {}) {
  * @param pkgs
  * @param {number=} depth
  */
-function toArchy (pkgs, depth) {
+function toArchy (pkgs, depth, cycleChecker) {
   if (depth <= 0) return []
   const result = pkgs.map(pkg => {
-    const blockSize = pkg.totalStats().totalBlockSize()
-    const dependencyCount = pkg.totalDependencies()
-    return {
-      label: `${pkg.packageJson._id}, ${chalk.red(blockSize / 1024 + 'k')}, ${dependencyCount} deps`,
-      size: blockSize,
-      nodes: toArchy(pkg.dependencies, depth && depth - 1)
+    if (cycleChecker.indexOf(pkg.packageJson._location) >= 0) {
+      return {
+        label: `${pkg.packageJson._id} (cycle detected)`,
+        size: undefined,
+        nodes: []
+      }
+    }
+    cycleChecker.push(pkg.packageJson._location)
+    try {
+      const blockSize = pkg.totalStats().totalBlockSize()
+      const dependencyCount = pkg.totalDependencies()
+      return {
+        label: `${pkg.packageJson._id}, ${chalk.red(blockSize / 1024 + 'k')}, ${dependencyCount} deps`,
+        size: blockSize,
+        nodes: toArchy(pkg.dependencies, depth && depth - 1, cycleChecker)
+      }
+    } finally {
+      cycleChecker.pop()
     }
   })
   return sortby(result, (node) => {

test/fixtures/moduleWithCyclicDeps.txt

@@ -0,0 +1,5 @@
+size: 42k... with-dependencies: 42k
+└─┬ dep1@1.0.0, 42k, 3 deps
+  └─┬ dep1a@1.0.0, 42k, 3 deps
+    └─┬ dep2@1.0.0, 42k, 3 deps
+      └── dep1@1.0.0 (cycle detected)

test/fixtures/moduleWithCyclicDeps/package.json

@@ -0,0 +1,8 @@
+{
+  "name": "moduleWithDeps",
+  "version": "1.0.0",
+  "dependencies": {
+    "dep1": "1.0.0",
+    "dep2": "1.0.0"
+  }
+}

test/index-spec.js

@@ -28,4 +28,22 @@ describe('The index-function (module main function):', function () {
         expect(result).to.equal(fs.readFileSync(`test/fixtures/moduleWithDeps-depth1-blk${blksize}-${process.platform}.txt`, 'utf-8'))
       })
   })
+
+  it('should handle cyclic dependencies gracefully', function () {
+    return analyze('test/fixtures/moduleWithCyclicDeps')
+      .then((result) => {
+        // The size numbers in this test are irrelevant. In order to keep the test compatible on multiple platforms,
+        // all sizes are set to 42k
+        expect(k24(result)).to.equal(k24(fs.readFileSync(`test/fixtures/moduleWithCyclicDeps.txt`, 'utf-8')))
+      })
+  })
 })
+
+/**
+ * Replace all kilobyte-numbers by 42k for comparibility if the numbers should not be part of the test
+ * @param string
+ * @return {*}
+ */
+function k24 (string) {
+  return string.replace(/\d+k/g, '42k')
+}