From 7d1793fbfef7d068fae247b9fe1bec87df86b9c3 Mon Sep 17 00:00:00 2001
From: Mihai Blaga <legolas8911@gmail.com>
Date: Sat, 22 May 2021 18:12:21 +0200
Subject: [PATCH 1/2] added packageManager cli option support

---
 packages/rnv/src/core/constants.js            |  8 +++++++
 .../rnv/src/core/systemManager/npmUtils.js    | 24 +++++++++++++++----
 2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/packages/rnv/src/core/constants.js b/packages/rnv/src/core/constants.js
index 124f7c38d2..742f1f7bbe 100644
--- a/packages/rnv/src/core/constants.js
+++ b/packages/rnv/src/core/constants.js
@@ -427,6 +427,14 @@ export const PARAM_KEYS = {
         isRequired: true,
         description: 'Use custom name for ./renative.json. (applies only at root level)'
     },
+    packageManager: {
+        value: 'value',
+        description: 'Specify the desired package manager to be used',
+        examples: [
+            '--packageManager yarn',
+            '--packageManager npm'
+        ]
+    }
 };
 
 Object.keys(PARAM_KEYS).forEach((k) => {
diff --git a/packages/rnv/src/core/systemManager/npmUtils.js b/packages/rnv/src/core/systemManager/npmUtils.js
index c22587f40e..5cbaab2fbf 100644
--- a/packages/rnv/src/core/systemManager/npmUtils.js
+++ b/packages/rnv/src/core/systemManager/npmUtils.js
@@ -154,11 +154,24 @@ export const installPackageDependencies = async (c, failOnError = false) => {
     const yarnLockPath = path.join(c.paths.project.dir, 'yarn.lock');
     const npmLockPath = path.join(c.paths.project.dir, 'package-lock.json');
     let command = 'npm install';
-    if (fsExistsSync(yarnLockPath)) {
-        command = 'yarn';
-    } else if (fsExistsSync(npmLockPath)) {
-        command = 'npm install';
-    } else if (isYarnInstalled) {
+
+
+    const yarnLockExists = fsExistsSync(yarnLockPath);
+    const packageLockExists = fsExistsSync(npmLockPath);
+
+    if (yarnLockExists || packageLockExists) {
+        // a lock file exists, defaulting to whichever is present
+        if (yarnLockExists && !isYarnInstalled) throw new Error('You have a yarn.lock file but you don\'t have yarn installed. Install it or delete yarn.lock');
+        command = yarnLockExists ? 'yarn' : 'npm install';
+    } else if (c.program.packageManager) {
+        // no lock file check cli option
+        if (['yarn', 'npm'].includes(c.program.packageManager)) {
+            command = c.program.packageManager === 'yarn' ? 'yarn' : 'npm install';
+        } else {
+            throw new Error(`Unsupported package manager ${c.program.packageManager}. Only yarn and npm are supported at the moment.`);
+        }
+    } else {
+        // no cli option either, asking
         const { packageManager } = await inquirerPrompt({
             type: 'list',
             name: 'packageManager',
@@ -168,6 +181,7 @@ export const installPackageDependencies = async (c, failOnError = false) => {
         });
         if (packageManager === 'yarn') command = 'yarn';
     }
+
     logTask('installPackageDependencies', `packageManager:(${command})`);
 
     try {

From 4f23f10a68e4086031ea08eac7bac7536b6e1a25 Mon Sep 17 00:00:00 2001
From: Mihai Blaga <legolas8911@gmail.com>
Date: Sat, 22 May 2021 18:15:42 +0200
Subject: [PATCH 2/2] extra check

---
 packages/rnv/src/core/systemManager/npmUtils.js | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/rnv/src/core/systemManager/npmUtils.js b/packages/rnv/src/core/systemManager/npmUtils.js
index 5cbaab2fbf..1a6a422305 100644
--- a/packages/rnv/src/core/systemManager/npmUtils.js
+++ b/packages/rnv/src/core/systemManager/npmUtils.js
@@ -167,6 +167,7 @@ export const installPackageDependencies = async (c, failOnError = false) => {
         // no lock file check cli option
         if (['yarn', 'npm'].includes(c.program.packageManager)) {
             command = c.program.packageManager === 'yarn' ? 'yarn' : 'npm install';
+            if (command === 'yarn' && !isYarnInstalled) throw new Error('You specified yarn as packageManager but it\'s not installed');
         } else {
             throw new Error(`Unsupported package manager ${c.program.packageManager}. Only yarn and npm are supported at the moment.`);
         }