feat: Add the project itself as an editable dependency

docs/advanced/pyproject_toml.md

@@ -14,8 +14,11 @@ platforms = ["linux-64", "osx-arm64", "osx-64", "win-64"]
 ```
 This is the minimum requirement for pixi to understand and parse the project.
 
-If you use `pixi init` in a folder that has a `pyproject.toml` file, pixi will automatically add the `[tool.pixi.project]` section to the file.
-And will also add some defaults to the `.gitignore` and `.gitattributes` file.
+However, it is recommended you use `pixi init` in a folder that has a `pyproject.toml` file. Pixi will automatically
+
+ - Add the above `[tool.pixi.project]` section to the file, auto-detecting your current platform;
+ - Add the current project as an editable pypi dependency;
+ - Add some defaults to the `.gitignore` and `.gitattributes` file.
 
 ## Python dependency
 The `pyproject.toml` file supports the `requires_python` field.
@@ -144,11 +147,19 @@ test = ["test"]
 ```
 
 ## Build-system section
-The `pyproject.toml` file normally contains a `[build-system]` section.
-Currently, pixi does not use this section, but it is recommended to keep it in the file for compatibility with other tools.
+The `pyproject.toml` file normally contains a `[build-system]` section.  Pixi will use this section to build and install the project if it is added as a pypi path dependency.
+
+If the `pyproject.toml` file does not contain any `[build-system]` section, pixi will fall back to [uv](https://github.com/astral-sh/uv)'s default, which is equivalent to the below:
+
+```toml title="pyproject.toml"
+[build-system]
+requires = ["setuptools >= 40.8.0"]
+build-backend = "setuptools.build_meta:__legacy__"
+```
+Including a `[build-system]` section is **highly recommended**. If you are not sure of the [build-backend](https://packaging.python.org/en/latest/tutorials/packaging-projects/#choosing-build-backend) you want to use, including the `[build-system]` section below in your `pyproject.toml` is a good starting point
 
 ```toml title="pyproject.toml"
 [build-system]
-requires = ["setuptools", "wheel"]
+requires = ["setuptools"]
 build-backend = "setuptools.build_meta"
 ```

examples/flask-hello-world-pyproject/.gitignore

@@ -0,0 +1 @@
+*.egg-info

examples/flask-hello-world-pyproject/pyproject.toml

@@ -2,16 +2,22 @@
 name = "flask-hello-world-pyproject"
 version = "0.1.0"
 description = "Example how to get started with flask in a pixi environment."
-license = "MIT OR Apache-2.0"
-homepage = "https://github.com/prefix/pixi"
 readme = "README.md"
 requires-python = ">=3.11"
-dependencies = ["flask==2.*"]
+dependencies = ["flask==2.*", "pytest"]
+
+[build-system]
+requires = ["setuptools", "wheel"]
+build-backend = "setuptools.build_meta"
 
 [tool.pixi.project]
 name = "flask-hello-world-pyproject"
 channels = ["conda-forge"]
-platforms = ["linux-64"]
+platforms = ["linux-64", "osx-arm64", "osx-64", "win-64"]
+
+[tool.pixi.pypi-dependencies]
+flask-hello-world-pyproject = { path = ".", editable = true }
 
 [tool.pixi.tasks]
-start = "python -m flask run --port=5050"
+start = "python -m flask --app flask_hello_world_pyproject.app:app run --port=5050"
+test = "pytest -v tests/*"

examples/flask-hello-world-pyproject/tests/test.py

@@ -0,0 +1,6 @@
+import flask_hello_world_pyproject  # noqa: F401
+
+
+def test_import():
+    """Simple test to validate the package itself has been installed."""
+    assert True

src/cli/init.rs

@@ -7,6 +7,7 @@ use clap::Parser;
 use indexmap::IndexMap;
 use miette::IntoDiagnostic;
 use minijinja::{context, Environment};
+use pyproject_toml::PyProjectToml;
 use rattler_conda_types::Platform;
 use std::io::{Error, ErrorKind, Write};
 use std::path::Path;
@@ -58,10 +59,14 @@ name = "{{ name }}"
 channels = [{%- if channels %}"{{ channels|join("\", \"") }}"{%- endif %}]
 platforms = ["{{ platforms|join("\", \"") }}"]
 
+[tool.pixi.pypi-dependencies]
+{{ name }} = { path = ".", editable = true }
+
 "#;
 
 const GITIGNORE_TEMPLATE: &str = r#"# pixi environments
 .pixi
+*.egg-info
 
 "#;
 
@@ -147,12 +152,20 @@ pub async fn execute(args: Args) -> miette::Result<()> {
         if pyproject_manifest_path.is_file() {
             let file = fs::read_to_string(pyproject_manifest_path.clone()).unwrap();
             if !file.contains("[tool.pixi.project]") {
+                // Get name from the pyproject [project] table
+                let name = match PyProjectToml::new(file.as_str()) {
+                    Ok(pyproject) => pyproject
+                        .project
+                        .map(|p| p.name)
+                        .expect("'name' should be defined in the [project] table"),
+                    Err(e) => miette::bail!("Failed to parse 'pyproject.toml'. Error is {}", e),
+                };
                 let rv = env
                     .render_named_str(
                         consts::PYPROJECT_MANIFEST,
                         PYROJECT_TEMPLATE,
                         context! {
-                            default_name,
+                            name,
                             channels,
                             platforms
                         },
@@ -169,6 +182,13 @@ pub async fn execute(args: Args) -> miette::Result<()> {
                         pyproject_manifest_path.to_string_lossy(),
                         e
                     );
+                } else {
+                    // Inform about the addition of the package itself as an editable dependency of the project
+                    eprintln!(
+                        "{}Added package '{}' as an editable dependency.",
+                        console::style(console::Emoji("✔ ", "")).green(),
+                        name
+                    );
                 }
             }
 

src/project/manifest/pyproject.rs

@@ -39,32 +39,31 @@ impl PyProjectManifest {
 
 impl From<PyProjectManifest> for ProjectManifest {
     fn from(item: PyProjectManifest) -> Self {
-        // Start by loading the data nested under "tool.pixi"
+        // Start by loading the data nested under "tool.pixi" as manifest,
+        // and create a reference to the 'pyproject.toml' project table
         let mut manifest = item.tool.pixi.clone();
+        let pyproject = item
+            .project
+            .as_ref()
+            .expect("the [project] table should exist");
 
         // TODO: tool.pixi.project.name should be made optional or read from project.name
         // TODO: could copy across / convert some other optional fields if relevant
 
         // Add python as dependency based on the project.requires_python property (if any)
-        let pythonspec = item
-            .project
-            .as_ref()
-            .and_then(|p| p.requires_python.as_ref())
-            .map(|v| VersionOrUrl::VersionSpecifier(v.clone()));
+        let pythonspec = pyproject
+            .requires_python
+            .clone()
+            .map(VersionOrUrl::VersionSpecifier);
         let target = manifest.default_feature_mut().targets.default_mut();
         target.add_dependency(
             PackageName::from_str("python").unwrap(),
             version_or_url_to_nameless_matchspec(&pythonspec).unwrap(),
             SpecType::Run,
         );
 
-        // add pyproject dependencies as pypi dependencies
-        if let Some(deps) = item
-            .project
-            .as_ref()
-            .and_then(|p| p.dependencies.as_ref())
-            .cloned()
-        {
+        // Add pyproject dependencies as pypi dependencies
+        if let Some(deps) = pyproject.dependencies.clone() {
             for d in deps.into_iter() {
                 target.add_pypi_dependency(
                     PyPiPackageName::from_normalized(d.name.clone()),
@@ -115,6 +114,9 @@ mod tests {
     };
 
     const PYPROJECT_FULL: &str = r#"
+        [project]
+        name = "project"
+
         [tool.pixi.project]
         name = "project"
         version = "0.1.0"

tests/test_examples.sh

@@ -12,3 +12,6 @@ pixi run -v --manifest-path examples/pypi-source-deps/pixi.toml test
 echo "Running the solve-groups example:"
 pixi run -v --manifest-path examples/solve-groups/pixi.toml -e min-py38 test
 pixi run -v --manifest-path examples/solve-groups/pixi.toml -e max-py310 test
+
+echo "Running the flask-hello-world-pyproject example:"
+pixi run -v --manifest-path examples/flask-hello-world-pyproject/pyproject.toml test