npm-pack-here

An alternative to the Yarn link and NPM link workflows, this tool packs a local NPM project and puts the packed contents into the given destination directories.

• Why npm-pack-here
• Demo
• Get started
  • Prerequisites
  • Installation
  • Upgrading
• Using npm-pack-here
  • Specifying Target Directories
  • Specifying Destination Directories
  • The Demo with Extra Details
  • When Done Testing
  • Running Continually (Watch Mode)
  • CLI Options
• Support
• Contributions
• Prior Art

Why npm-pack-here

When testing a locally cloned npm project within another locally cloned project it is common to use yarn link or npm link to setup a folder level symlink to the project under test. This has a two unfortunate side effects,

• The testing project only has the single node_modules folder symlinked and none-of the other project dependencies are changed. So if the project under test has changed its dependencies, the node_modules tree is not updated to reflect that. As a result subtle transitive dependency changes (due to different versions being "lifted" by npm/yarn) are not seen until after the project under test has released a new package version on npm.
• Since a symlink is used, all the dependency resolution is in a single direction, the project under test still only knows about its own node_modules tree and knows nothing about the testing projects node_modules tree. This often leads to duplicate dependencies (which should have resolved as the same version), which frequently results in issues. We find this to be especially true with typescript typings projects. For example if the project under test exports a react component (using typings defined in @types/react) this almost always breaks the typescript compiler as even the exact same version of the types will lead to typescript failing to compile.

To resolve these problems you could attempt to do one of following workflows (let's assume you have a projectB which has a dependency on a projectA),

1. Add a 'file' reference to projectB that references the local location of projectA (after running yarn install/npm install this results in a copy of projectA being put into projectB's node_modules directory). There are two problems with this approach. First, it takes forever since the node_modules directory in projectA is also copied. Second, because it copies the node_modules directory in projectA, you end up running into the same issues described above. To maybe make it work, the node_modules directory in projectA has to be deleted, which might or might not work depending on if projectB has different versions of the same dependencies as projectA.
2. Run npm pack in projectA (which collects all of the content that would be published into a tarball), then add a file reference to this packaged version of projectA in projectB. Now running yarn install or npm install will result in the expected node_modules tree. Except now different issues occur, first is that yarn has a bug where it will inappropriately cache 'packaged' tarballs in the global yarn cache. This means re-packaging projectA won't result in the changes being picked up in projectB (unless you delete the yarn cache for projectA). Also any time projectA changes you have to re-run the pack command and then the yarn/npm install commands. Which is usually pretty slow and and causes most watch scripts to break.
3. Run npm pack in projectA, then untar the packaged files into a directory in projectB. Finally, add a file/link reference to this folder in projectB. After running yarn install or npm install this will result in the expected node_modules tree. This is the most reliable way to do testing of local projects and seems to work well with both yarn and npm. It has the same speed issues as number 2 above whenever updating projectA (have to repack projectA, and then untar it anytime you want to pull in new content into projectB) and will break watch scripts.

This project essentially automates the third workflow above with additional smart file copying to ensure watch scripts behave as expected. Also has support for performing this workflow for multi-level local dependency chains (C depends on B which depends on A).

Demo

Imagine that you have a projectB that has a dependency on a projectA (in this example we are assuming yarn v1 is being used as the package management tool).

In the root directory of projectB, run the following:

npm-pack-here --target [path-to-projectA]
yarn add file:local_modules/[name-of-projectA]
yarn install --check-files

Example output:

[path-to-projectB]> npm-pack-here -t [path-to-projectA]
Copying packed files from - [path-to-projectA]
  to - [path-to-projectB]/local_modules/[name-of-projectA]
  to - [path-to-projectB]/node_modules/[name-of-projectA]
[success] Done copying packed files from - [path-to-projectA]

Set up target projects as local dependencies with yarn using:
        yarn add file:local_modules/[name-of-projectA]
        yarn install --check-files

To get updated changes from target projects, run this command again.
        npm-pack-here --target [path-to-projectA]
  or watch continually
        npm-pack-here watch --target [path-to-projectA]

[path-to-projectB]> yarn add file:local_modules/[name-of-projectA]
…

[path-to-projectB]> yarn install --check-files
…

At this point everything is setup, projectB should be using your local version of projectA

After a while say you want to make an update to projectA, once the update is made just run the first npm-pack-here command again:

npm-pack-here --target [path-to-projectA]

Example output:

[path-to-projectB]> npm-pack-here --target [path-to-projectA]
Copying packed files from - [path-to-projectA]
  to - [path-to-projectB]\local_modules\[name-of-projectA]
  to - [path-to-projectB]\node_modules\[name-of-projectA]
[success] Done copying packed files from - [path-to-projectA]

Get started

Prerequisites

To work with npm-pack-here, you need the following:

• At least the most recent LTS version of node
• If using yarn,
  • a recent release of yarn v1, or
  • a recent release of yarn v2+ using the node-modules linker. npm-pack-here is probably not useful with the other linkers.

Installation

Install as a global yarn or npm dependency,

npm install -g npm-pack-here

The latest version of the script can now be run using the command npm-pack-here (should be immediately available on your path).

Upgrading

To get the latest version of npm-pack-here, run the install command again

Using npm-pack-here

At its core npm-pack-here will identify the packaged content of some set of target source projects and then place them within some set of destination directories. The two core pieces of information that it needs to run are the set of target directories and the set of destination directories.

Specifying Target Directories

To specify the target directories simply pass them in via the required --target parameter.

Specifying Destination Directories

To specify the destination directories there are a variety of options which will depend on your required workflow,

Note: The packaged content is still placed within sub-directories (named using the projects name) within the specified destination directories

Specify Destination Directories Directly

Using the --destinations argument (defaults to the single directory ./local_modules) you can specify the destination directories directly.

Specify A Global Destination Directory Location

Using the --useGlobalCache argument you can specify that a global location should be used as the destination.

Note: this can only be done instead of specifying the --destinations argument

This is helpful when trying to test a diamond dependency situation. It will force yarn/npm to use absolute paths when resolving dependencies which means the root dependency will resolve to the same version instead of two different versions.

Specify that node_modules Sub-Directories Should Be Included as Destinations

Since npm-pack-here was designed to be used for testing two locally cloned npm projects with one another, by default the script will detect a node_modules directory in the current working directory and add the correct sub-directories of node_modules as destinations (using node's require.resolve algorithm). If this behavior is not desired it can be disabled by passing false to the --updateRelativeNodeModulesDirectory argument.

The Demo with Extra Details

Lets walk through the common workflow that the Demo above demonstrated. Imagine that you have a projectB that has a dependency on a projectA and are using yarn as your dependency management tool.

In the root directory of projectB, run:

npm-pack-here --target [path-to-projectA]

This will copy the 'packaged' version of projectA into projectB's ./local_modules and ./node_modules directories. To prevent accidental check-in of ./local_modules, consider adding the folder to projectB's .gitignore file (or be sure to delete/revert the directory when you are done).

Next, add a file reference dependency. In the root directory of projectB, run:

yarn add file:./local_modules/[name-of-projectA]

Replace [name-of-projectA] with your actual project name. This will set up yarn to use the local copy when resolving dependencies.

Often I find due to yarn not always checking transitive dependencies a follow up install command is required.

yarn install --check-files

Work in projectB and projectA as usual. When you are ready to push new changes in projectA to projectB, repeat the first step. In the root directory of projectB run:

npm-pack-here --target [path-to-projectA]

Note: If you added or remove a dependency to projectA, run yarn install --check-files again to ensure the dependency tree in projectB is updated accordingly

Note: If you do not want to run this command every time you want to push updates check out the Running Continually section below

When Done Testing

When you are done testing locally and you want to get back to using the version of projectA in the binary repository, revert the projectB line with the file: reference in your package.json and re-run yarn install --check-files. This should result in your yarn.lock file being reverted and your node_modules tree being repopulated with its original content. Also remember to delete the copy of the packaged content in projectB's local_modules directory. Note this is not required if you added the local_modules directory to projectB's .gitignore.

Running Continually (Watch Mode)

The script supports a watch mode so that after performing the initial file copies it will continually update the destination directories with changes as the packaged content in the target directories are updated.

To use it run the same command with watch added before any other arguments

npm-pack-here watch --target [path-to-projectA]

CLI Options

Required Options

target (Required)

Directories containing npm projects to be packaged and copied to destination directories [array] [required]

If testing with multiple local projects, multiple targets may be passed in to bring all of their packed content into the destination directories.

Optional Options

The defaults for these options should work in almost all standard cases, but there might be times more flexibility is required.

destinations (Optional)

Directories to copy packaged content to [array] [default: ["./local_modules"]]

excludedDestinationPaths (Optional)

Globs for file and directory paths in the destination directory to exclude from being replaced [array] [default: ["node_modules"]]

useGlobalCache (Optional)

Used instead of the destinations argument, currently experimental so defaults to being false. Will place the packaged content in a global location instead of ./local_modules. This is useful if you want to locally test a multi-level diamond dependency graph, if every level depends on a locally packaged version of their sub-dependencies then when you roll up to the top level you end up with multiple versions of the same packages. Using a global location results in yarn or npm treating them all as if they where the same dependency.

updateRelativeNodeModulesDirectory (Optional)

Defaults to true, if set will attempt to add the correct directories from the local node_modules directory to the list of destinations. Uses node's require.resolve algorithm to ensure the correct node_modules directories are updated. With this argument set, all locally specified target dependencies are also packed into the working directory's node_modules directory.

Troubleshooting

Npm-pack-here runs but webpack (or other bundler) doesn’t detect any changes

As of Webpack v5 the default caching settings will likely cause issues when attempting to do local testing with npm-pack-here. The problem is the snapshot.managedPaths default value includes the node_modules directory. With this default setting, webpack’s caching does not seem to detect any changes to file: dependencies as different. To resolve this, add snapshot.managedPaths = [] to your configuration to override the default value.

Another common source of trouble is the watchOptions.ignored setting. If the project’s webpack configuration has added node_modules as ignored then any changes to project’s dependencies will require a restart of webpack’s dev mode.

Other bundlers are known to have similar problems, if you encounter them let us know about it so we can document it here as well.

Support

If you encounter any surprising or unexpected behavior using this tool or have any questions, please feel free to open an issue. This tool is Community Supported so Tableau Developers will periodically review any open issues.

If you would like to expand the capabilities of what npm-pack-here does, we are open to ideas that will not be disruptive to the existing supported workflows. Be warned that we have no plans to grow the problem space that this tool intends to solve. Also we do not want for this tool to become a proxy for yarn or npm. We encourage anyone to build off of our work to solve other problems.

Contributions

See Contributing for details.

Prior Art

An existing project yalc was part of the inspiration for this one. It is attempting to solve the same problem in a more complex way. Due to the extra complexity it did not work for us as we needed it to, so built this solution to be more focused on the exact problem we needed solved.