Improve UX for pack and publish path expectations

docs/pack-and-publish.md

@@ -0,0 +1,32 @@
+# pack and publish 
+
+The `publish` and `pack` commands interact with the pkg directory that's 
+created when you run `wasm-pack init`. The `pack` command creates a tarball
+from the pkg directory and the `publish` command creates a tarball from the 
+pkg directory __and__ publishes it to the NPM registry. 
+
+Underneath, these commands use `npm pack` and `npm publish`. You can read
+more about these in the NPM documentation:
+
+- [`npm pack`](https://docs.npmjs.com/cli/pack)
+- [`npm publish`](https://docs.npmjs.com/cli/publish)
+
+Both these commands take the path to the pkg directory as the first argument. 
+You can either set the argument directly to the pkg directory or to the parent 
+of the pkg directory:
+
+```
+$ wasm-pack pack myproject/pkg
+| 🎒  packed up your package!
+$ wasm-pack pack myproject
+| 🎒  packed up your package!
+```
+
+If you try to call `pack` or `publish` on another directory, you get an error:
+
+```
+$ wasm-pack pack myproject/src/
+Unable to find the pkg directory at path 'myproject/src/', or in a child directory of 'myproject/src/'
+```
+
+If you don't set a path, they use the current directory as the path.

src/command/pack.rs

@@ -1,15 +1,23 @@
-use command::utils::set_crate_path;
+use command::utils::{find_pkg_directory, set_crate_path};
 use error::Error;
 use npm;
 use slog::Logger;
 use std::result;
 use PBAR;
 
+/// Executes the 'npm pack' command on the 'pkg' directory
+/// which creates a tarball that can be published to the NPM registry
 pub fn pack(path: Option<String>, log: &Logger) -> result::Result<(), Error> {
     let crate_path = set_crate_path(path);
 
     info!(&log, "Packing up the npm package...");
-    npm::npm_pack(&crate_path)?;
+    let pkg_directory = find_pkg_directory(&crate_path).ok_or(Error::PkgNotFound {
+        message: format!(
+            "Unable to find the pkg directory at path '{}', or in a child directory of '{}'",
+            &crate_path, &crate_path
+        ),
+    })?;
+    npm::npm_pack(&pkg_directory.to_string_lossy())?;
     #[cfg(not(target_os = "windows"))]
     info!(&log, "Your package is located at {}/pkg", &crate_path);
     #[cfg(target_os = "windows")]

src/command/publish.rs

@@ -1,16 +1,25 @@
-use command::utils::set_crate_path;
+use command::utils::{find_pkg_directory, set_crate_path};
 use error::Error;
 use npm;
 use slog::Logger;
 use std::result;
 use PBAR;
 
+/// Creates a tarball from a 'pkg' directory
+/// and publishes it to the NPM registry
 pub fn publish(path: Option<String>, log: &Logger) -> result::Result<(), Error> {
     let crate_path = set_crate_path(path);
 
     info!(&log, "Publishing the npm package...");
     info!(&log, "npm info located in the npm debug log");
-    npm::npm_publish(&crate_path)?;
+    let pkg_directory = find_pkg_directory(&crate_path).ok_or(Error::PkgNotFound {
+        message: format!(
+            "Unable to find the pkg directory at path '{}', or in a child directory of '{}'",
+            &crate_path, &crate_path
+        ),
+    })?;
+
+    npm::npm_publish(&pkg_directory.to_string_lossy())?;
     info!(&log, "Published your package!");
 
     PBAR.message("💥  published your package!");

src/command/utils.rs

@@ -1,5 +1,7 @@
 //! Utility functions for commands.
 
+use std::path::{Path, PathBuf};
+
 /// If an explicit path is given, then use it, otherwise assume the current
 /// directory is the crate path.
 pub fn set_crate_path(path: Option<String>) -> String {
@@ -10,3 +12,22 @@ pub fn set_crate_path(path: Option<String>) -> String {
 
     crate_path
 }
+
+/// Locates the pkg directory from a specific path
+/// Returns None if unable to find the 'pkg' directory
+pub fn find_pkg_directory(guess_path: &str) -> Option<PathBuf> {
+    let path = PathBuf::from(guess_path);
+    if is_pkg_directory(&path) {
+        return Some(path);
+    }
+
+    path.read_dir().ok().and_then(|entries| {
+        entries
+            .filter_map(|x| x.ok().map(|v| v.path()))
+            .find(|x| is_pkg_directory(&x))
+    })
+}
+
+fn is_pkg_directory(path: &Path) -> bool {
+    path.exists() && path.is_dir() && path.ends_with("pkg")
+}

src/error.rs

@@ -34,6 +34,12 @@ pub enum Error {
         /// A message describing the configuration error.
         message: String,
     },
+    #[fail(display = "{}", message)]
+    /// Error when the 'pkg' directory is not found.
+    PkgNotFound {
+        /// Message describing the error.
+        message: String,
+    },
 }
 
 impl Error {
@@ -65,6 +71,9 @@ impl Error {
             Error::CrateConfig { message: _ } => {
                 "There was a crate configuration error. Details:\n\n"
             }
+            Error::PkgNotFound {
+                message: _,
+            } => "Unable to find the 'pgk' directory at the path, set the path as the parent of the 'pkg' directory \n\n",
         }.to_string()
     }
 }

src/npm.rs

@@ -8,11 +8,7 @@ pub const DEFAULT_NPM_REGISTRY: &'static str = "https://registry.npmjs.org/";
 
 /// Run the `npm pack` command.
 pub fn npm_pack(path: &str) -> Result<(), Error> {
-    let pkg_file_path = format!("{}/pkg", path);
-    let output = Command::new("npm")
-        .current_dir(pkg_file_path)
-        .arg("pack")
-        .output()?;
+    let output = Command::new("npm").current_dir(path).arg("pack").output()?;
     if !output.status.success() {
         let s = String::from_utf8_lossy(&output.stderr);
         Error::cli("Packaging up your code failed", s)
@@ -23,9 +19,8 @@ pub fn npm_pack(path: &str) -> Result<(), Error> {
 
 /// Run the `npm publish` command.
 pub fn npm_publish(path: &str) -> Result<(), Error> {
-    let pkg_file_path = format!("{}/pkg", path);
     let output = Command::new("npm")
-        .current_dir(pkg_file_path)
+        .current_dir(path)
         .arg("publish")
         .output()?;
     if !output.status.success() {