From 4d23be2cd9758fc4a12423e721ffce6d1c47c122 Mon Sep 17 00:00:00 2001
From: raika-dev <derikkandev@gmail.com>
Date: Sun, 24 May 2020 11:01:34 -0700
Subject: [PATCH] Handle semantically scoped @ modules when finding dupes.

---
 src/resolve/duplicateModules.test.ts | 35 ++++++++++++++++++++-
 src/resolve/duplicateModules.ts      | 47 +++++++++++++++++++++++++++-
 2 files changed, 80 insertions(+), 2 deletions(-)

diff --git a/src/resolve/duplicateModules.test.ts b/src/resolve/duplicateModules.test.ts
index 3e2704f..940bc8c 100644
--- a/src/resolve/duplicateModules.test.ts
+++ b/src/resolve/duplicateModules.test.ts
@@ -1,4 +1,17 @@
-import { findDuplicateModules } from "./duplicateModules";
+import {
+  findDuplicateModules,
+  splitBySemanticModulePath
+} from "./duplicateModules";
+
+it("handles non-scoped packages", () => {
+  const ret = splitBySemanticModulePath("foo/node_modules/zap/tap");
+  expect(ret).toEqual(["foo", "node_modules", "zap", "tap"]);
+});
+
+it("handles @scoped packages", () => {
+  const ret = splitBySemanticModulePath("foo/node_modules/@zap/tap");
+  expect(ret).toEqual(["foo", "node_modules", "@zap/tap"]);
+});
 
 it("handles one module", () => {
   const ret = findDuplicateModules(["foo/zap/node_modules/tap"]);
@@ -15,6 +28,26 @@ it("handles multiple modules", () => {
   expect(ret.length).toBe(0);
 });
 
+it("correctly splits @ scoped modules", () => {
+  const ret = findDuplicateModules([
+    "foo/zap/node_modules/@tap/wow",
+    "foo/zap/node_modules/no/node_modules/@tap/zap"
+  ]);
+
+  expect(ret.length).toBe(0);
+});
+
+it("correctly find duplicated @ scoped modules", () => {
+  const ret = findDuplicateModules([
+    "foo/zap/node_modules/@tap/wow",
+    "foo/zap/node_modules/no/node_modules/@tap/wow"
+  ]);
+
+  expect(ret.length).toBe(1);
+  expect(ret[0].key).toBe("@tap/wow");
+  expect(ret[0].value.sort()).toEqual(["<PROJECT ROOT>", "no"]);
+});
+
 it("handles duplicate modules", () => {
   const ret = findDuplicateModules([
     "foo/zap/node_modules/tap",
diff --git a/src/resolve/duplicateModules.ts b/src/resolve/duplicateModules.ts
index 4f2d0b9..f56d0d5 100644
--- a/src/resolve/duplicateModules.ts
+++ b/src/resolve/duplicateModules.ts
@@ -1,3 +1,48 @@
+/**
+ * Splits the folder path by semantically scoped package path.
+ *
+ * For example
+ * node_modules/@foo/zap becomes ["node_modules", "@foo/zap"]
+ *
+ * vs:
+ * node_modules/foo/zap becomes ["node_modules", "foo", "zap"]
+ *
+ * @param path file path to split
+ */
+export function splitBySemanticModulePath(path: string): string[] {
+  let folderSplit = path.split("/");
+
+  const ret: string[] = [];
+  let scopedPackage = "";
+  let lastNodeModules = false;
+
+  for (const p of folderSplit) {
+    if (p === "node_modules") {
+      lastNodeModules = true;
+      ret.push(p);
+      continue;
+    }
+
+    if (lastNodeModules && p[0] === "@") {
+      scopedPackage = p;
+      lastNodeModules = false;
+      continue;
+    }
+
+    lastNodeModules = false;
+
+    if (scopedPackage.length) {
+      ret.push(`${scopedPackage}/${p}`);
+      scopedPackage = "";
+      continue;
+    }
+
+    ret.push(p);
+  }
+
+  return ret;
+}
+
 /**
  * Given a list of files find duplicate node modules and the dependencies that
  * brought them into the project.
@@ -17,7 +62,7 @@ export function findDuplicateModules(
     v => v.indexOf("node_modules") > -1
   );
   const explodedPaths = containsNodeModules
-    .map(v => v.split("/"))
+    .map(v => splitBySemanticModulePath(v))
     .map(splitPath => {
       return {
         nodeModulePreamables: splitPath