Scaffold the build interface

The `Builder` struct defines the public interface for building a PGXN
release. Internally, it delegates `configure`, `compile`, and `test`
commands (so far) to pipeline-specific build modules. Its `new`
constructor reads the pgxn_meta Release pipeline to determine which one
to instantiate; in the future it will also fall back on detecting the
pipeline where none is specified.

The `error` module define errors returned by the crate, while the
`pipeline` module defines a trait with the functions `Builder` expects
to dispatch to. All pipelines must implement this trait. This will make
it easy to add new pipelines in the future; They just have to implement
the trait, add a new `Build` enum, then add appropriate calls to its
methods in `Builder`'s dispatching methods.

For now, the `pgxs` and `pgrx` modules alone define structs that
implement the `pipeline.Pipeline` trait with no-op functions.

Add tests for basic functionality of `Builder`.

Cargo.toml

@@ -4,4 +4,8 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+pgxn_meta = "0.4"
 thiserror = "1.0"
+
+[dev-dependencies]
+serde_json = "1.0.128"

src/error/mod.rs

@@ -0,0 +1,14 @@
+//! Build Errors.
+use thiserror::Error;
+
+/// Build errors.
+#[derive(Error, Debug, PartialEq)]
+pub enum BuildError {
+    /// Errors configuring a build.
+    #[error("configuration failure")]
+    Configuration(),
+
+    /// Unknown pipeline error.
+    #[error("unknown build pipeline `{0}`")]
+    UnknownPipeline(String),
+}

src/lib.rs

@@ -7,45 +7,79 @@ This crate builds PGXN distributions for a variety of platforms and Postgres
 versions.
 
 */
-use thiserror::Error;
-
-/// Build errors.
-#[derive(Error, Debug)]
-pub enum BuildError {
-    /// Errors configuring a build.
-    #[error("configuration failure")]
-    Configuration(),
+pub mod error;
+mod pgrx;
+mod pgxs;
+mod pipeline;
+
+use crate::{error::BuildError, pgrx::Pgrx, pgxs::Pgxs, pipeline::Pipeline};
+use pgxn_meta::{dist, release::Release};
+
+/// Defines the types of builders.
+#[derive(Debug, PartialEq)]
+enum Build {
+    /// Defines a builder using the PGXS pipeline.
+    Pgxs(Pgxs),
+
+    /// Defines a builder using the pgrx pipeline.
+    Pgrx(Pgrx),
 }
 
-/// Defines the interface for downloading, configuring, building, and testing
-/// PGXN distributions.
-pub trait Builder {
-    /// Downloads a distribution.
-    fn download() -> Result<(), BuildError>;
+/// Builder builds PGXN releases.
+#[derive(Debug, PartialEq)]
+pub struct Builder(Build);
 
-    /// Unpacks a downloaded distribution.
-    fn unpack() -> Result<(), BuildError>;
+impl Builder {
+    /// Creates and returns a new builder using the appropriate pipeline.
+    pub fn new(meta: Release) -> Result<Self, BuildError> {
+        if let Some(deps) = meta.dependencies() {
+            if let Some(pipeline) = deps.pipeline() {
+                return match pipeline {
+                    dist::Pipeline::Pgxs => Ok(Builder(Build::Pgxs(Pgxs::new(meta)))),
+                    dist::Pipeline::Pgrx => Ok(Builder(Build::Pgrx(Pgrx::new(meta)))),
+                    _ => Err(BuildError::UnknownPipeline(pipeline.to_string())),
+                };
+            }
+        }
+        println!("HERE");
+        todo!("Detect pipeline");
+    }
 
-    /// Patches a distribution.
-    fn patch() -> Result<(), BuildError>;
+    /// Downloads a release.
+    pub fn download(&self) -> Result<(), BuildError> {
+        Ok(())
+    }
+
+    /// Unpacks a release.
+    pub fn unpack(&self) -> Result<(), BuildError> {
+        Ok(())
+    }
 
     /// Configures a distribution to build on a particular platform and
     /// Postgres version.
-    fn configure() -> Result<(), BuildError>;
+    pub fn configure(&self) -> Result<(), BuildError> {
+        match &self.0 {
+            Build::Pgxs(pgxs) => pgxs.configure(),
+            Build::Pgrx(pgrx) => pgrx.configure(),
+        }
+    }
 
     /// Compiles a distribution on a particular platform and Postgres version.
-    fn compile() -> Result<(), BuildError>;
+    pub fn compile(&self) -> Result<(), BuildError> {
+        match &self.0 {
+            Build::Pgxs(pgxs) => pgxs.compile(),
+            Build::Pgrx(pgrx) => pgrx.compile(),
+        }
+    }
 
     /// Tests a distribution a particular platform and Postgres version.
-    fn test() -> Result<(), BuildError>;
+    pub fn test(&self) -> Result<(), BuildError> {
+        match &self.0 {
+            Build::Pgxs(pgxs) => pgxs.test(),
+            Build::Pgrx(pgrx) => pgrx.test(),
+        }
+    }
 }
 
 #[cfg(test)]
-mod tests {
-    // use super::*;
-
-    #[test]
-    fn it_works() {
-        assert!(true == true);
-    }
-}
+mod tests;

src/pgrx/mod.rs

@@ -0,0 +1,32 @@
+//! Builder implementation for [pgrx] Pipelines.
+//!
+//! [pgrx]: https://github.com/pgcentralfoundation/pgrx
+
+use crate::error::BuildError;
+use crate::pipeline::Pipeline;
+use pgxn_meta::release::Release;
+
+/// Builder implementation for [pgrx] Pipelines.
+///
+/// [pgrx]: https://github.com/pgcentralfoundation/pgrx
+#[derive(Debug, PartialEq)]
+pub(crate) struct Pgrx {
+    meta: Release,
+}
+
+impl Pipeline for Pgrx {
+    fn new(meta: Release) -> Self {
+        Pgrx { meta }
+    }
+    fn configure(&self) -> Result<(), BuildError> {
+        Ok(())
+    }
+
+    fn compile(&self) -> Result<(), BuildError> {
+        Ok(())
+    }
+
+    fn test(&self) -> Result<(), BuildError> {
+        Ok(())
+    }
+}

src/pgxs/mod.rs

@@ -0,0 +1,33 @@
+//! Builder implementation for [PGXS] Pipelines.
+//!
+//! [PGXS]: https://www.postgresql.org/docs/current/extend-pgxs.html
+
+use crate::error::BuildError;
+use crate::pipeline::Pipeline;
+use pgxn_meta::release::Release;
+
+/// Builder implementation for [PGXS] Pipelines.
+///
+/// [PGXS]: https://www.postgresql.org/docs/current/extend-pgxs.html
+#[derive(Debug, PartialEq)]
+pub(crate) struct Pgxs {
+    meta: Release,
+}
+
+impl Pipeline for Pgxs {
+    fn new(meta: Release) -> Self {
+        Pgxs { meta }
+    }
+
+    fn configure(&self) -> Result<(), BuildError> {
+        Ok(())
+    }
+
+    fn compile(&self) -> Result<(), BuildError> {
+        Ok(())
+    }
+
+    fn test(&self) -> Result<(), BuildError> {
+        Ok(())
+    }
+}

src/pipeline/mod.rs

@@ -0,0 +1,21 @@
+//! Build Pipeline interface definition.
+
+use crate::error::BuildError;
+use pgxn_meta::release::Release;
+
+/// Defines the interface for build pipelines to configure, compile, and test
+/// PGXN distributions.
+pub(crate) trait Pipeline {
+    /// Creates an instance of a Builder.
+    fn new(meta: Release) -> Self;
+
+    /// Configures a distribution to build on a particular platform and
+    /// Postgres version.
+    fn configure(&self) -> Result<(), BuildError>;
+
+    /// Compiles a distribution on a particular platform and Postgres version.
+    fn compile(&self) -> Result<(), BuildError>;
+
+    /// Tests a distribution a particular platform and Postgres version.
+    fn test(&self) -> Result<(), BuildError>;
+}

src/tests.rs

@@ -0,0 +1,102 @@
+use super::*;
+use serde_json::{json, Value};
+
+fn release_meta(pipeline: &str) -> Value {
+    json!({
+      "name": "pair",
+      "abstract": "A key/value pair data type",
+      "version": "0.1.8",
+      "maintainers": [
+        { "name": "David E. Wheeler", "email": "[email protected]" }
+      ],
+      "license": "PostgreSQL",
+      "contents": {
+        "extensions": {
+          "pair": {
+            "sql": "sql/pair.sql",
+            "control": "pair.control"
+          }
+        }
+      },
+      "dependencies": { "pipeline": pipeline },
+      "meta-spec": { "version": "2.0.0" },
+      "certs": {
+        "pgxn": {
+          "payload": "eyJ1c2VyIjoidGhlb3J5IiwiZGF0ZSI6IjIwMjQtMDktMTNUMTc6MzI6NTVaIiwidXJpIjoiZGlzdC9wYWlyLzAuMS43L3BhaXItMC4xLjcuemlwIiwiZGlnZXN0cyI6eyJzaGE1MTIiOiJiMzUzYjVhODJiM2I1NGU5NWY0YTI4NTllN2EyYmQwNjQ4YWJjYjM1YTdjMzYxMmIxMjZjMmM3NTQzOGZjMmY4ZThlZTFmMTllNjFmMzBmYTU0ZDdiYjY0YmNmMjE3ZWQxMjY0NzIyYjQ5N2JjYjYxM2Y4MmQ3ODc1MTUxNWI2NyJ9fQ",
+          "signature": "DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8ISlSApmWQxfKTUJqPP3-Kg6NU1Q",
+        },
+      },
+    })
+}
+
+#[test]
+fn pgxs() {
+    // Test pgxs pipeline.
+    let meta = release_meta("pgxs");
+    let rel = Release::try_from(meta.clone()).unwrap();
+    let builder = Builder::new(rel).unwrap();
+    let rel = Release::try_from(meta).unwrap();
+    let exp = Builder(Build::Pgxs(Pgxs::new(rel)));
+    assert_eq!(exp, builder, "pgxs");
+    assert!(builder.download().is_ok());
+    assert!(builder.unpack().is_ok());
+    assert!(builder.configure().is_ok());
+    assert!(builder.compile().is_ok());
+    assert!(builder.test().is_ok());
+}
+
+#[test]
+fn pgrx() {
+    // Test pgrx pipeline.
+    let meta = release_meta("pgrx");
+    let rel = Release::try_from(meta.clone()).unwrap();
+    let builder = Builder::new(rel).unwrap();
+    let rel = Release::try_from(meta).unwrap();
+    let exp = Builder(Build::Pgrx(Pgrx::new(rel)));
+    assert_eq!(exp, builder, "pgrx");
+    assert!(builder.download().is_ok());
+    assert!(builder.unpack().is_ok());
+    assert!(builder.configure().is_ok());
+    assert!(builder.compile().is_ok());
+    assert!(builder.test().is_ok());
+}
+
+#[test]
+fn unsupported_pipeline() {
+    // Test unsupported pipeline.
+    let meta = release_meta("meson");
+    let rel = Release::try_from(meta).unwrap();
+    assert_eq!(
+        BuildError::UnknownPipeline("meson".to_string()),
+        Builder::new(rel).unwrap_err(),
+    );
+}
+
+#[test]
+#[should_panic(expected = "Detect pipeline")]
+fn detect_pipeline() {
+    // Test unspecified pipeline.
+    let mut meta = release_meta("");
+    meta.as_object_mut().unwrap().remove("dependencies");
+    let rel = Release::try_from(meta).unwrap();
+    _ = Builder::new(rel);
+}
+
+#[test]
+#[should_panic(expected = "Detect pipeline")]
+fn no_pipeline() {
+    // Test unspecified pipeline.
+    let mut meta = release_meta("");
+    let deps = meta
+        .as_object_mut()
+        .unwrap()
+        .get_mut("dependencies")
+        .unwrap()
+        .as_object_mut()
+        .unwrap();
+
+    deps.remove("pipeline");
+    deps.insert("postgres".to_string(), json!({"version": "14"}));
+    let rel = Release::try_from(meta).unwrap();
+    _ = Builder::new(rel);
+}