feat(Zsh microkernel): Add Zsh microkernel

Zsh is now the default shell on MacOS (since Catalina).

rust/kernel-zsh/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "kernel-zsh"
+description = "A microkernel for Zsh"
+version = "0.0.0"
+edition = "2021"
+
+[dependencies]
+kernel = { path = "../kernel", version = "0.0.0" }
+kernel-micro = { path = "../kernel-micro", version = "0.0.0" }
+
+[dev-dependencies]
+tokio = { version = "1.13.0", features = ["macros"] }
+test-utils = { path = "../test-utils", version = "0.0.0" }

rust/kernel-zsh/src/lib.rs

@@ -0,0 +1,73 @@
+use kernel_micro::{include_file, MicroKernel};
+
+/// A microkernel for Zsh
+///
+/// The `kernel-zsh.sh` script relies on `/dev/stdin`, `/dev/stdout`,
+/// and `/dev/stderr` so this kernel is not available on Windows.
+pub fn new() -> MicroKernel {
+    MicroKernel::new(
+        "zsh-micro",
+        &["zsh"],
+        &["linux", "macos", "windows"],
+        ("zsh", "*"),
+        &["{{script}}"],
+        include_file!("zsh-kernel.sh"),
+        &[],
+        "{{name}}=\"{{json}}\"",
+        "echo ${{name}}",
+    )
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use kernel::{eyre::Result, stencila_schema::Node, KernelTrait};
+    use test_utils::{assert_json_eq, print_logs, serde_json::json};
+
+    /// Tests of basic functionality
+    /// This test is replicated in all the microkernels.
+    /// Other test should be written for language specific quirks and regressions.
+    #[tokio::test]
+    async fn basics() -> Result<()> {
+        print_logs();
+
+        let mut kernel = new();
+        if !kernel.available().await {
+            return Ok(());
+        } else {
+            kernel.start().await?;
+        }
+
+        // Assign a variable and output it
+        let (outputs, messages) = kernel.exec("a=2\necho $a").await?;
+        assert_json_eq!(messages, json!([]));
+        assert_json_eq!(outputs, [2]);
+
+        // Syntax error
+        let (outputs, messages) = kernel.exec("if").await?;
+        messages[0]
+            .error_message
+            .ends_with("syntax error: unexpected end of file\n");
+
+        assert_json_eq!(outputs, json!([]));
+
+        // Runtime error
+        let (outputs, messages) = kernel.exec("foo").await?;
+        messages[0]
+            .error_message
+            .ends_with("foo: command not found\n");
+        assert_json_eq!(outputs, json!([]));
+
+        // Set and get another variable
+        kernel.set("b", Node::Integer(3)).await?;
+        let b = kernel.get("b").await?;
+        assert_json_eq!(b, 3);
+
+        // Use both variables
+        let (outputs, messages) = kernel.exec("echo $a$b").await?;
+        assert_json_eq!(messages, json!([]));
+        assert_json_eq!(outputs, [23]);
+
+        Ok(())
+    }
+}

rust/kernel-zsh/src/zsh-kernel.sh

@@ -0,0 +1,8 @@
+#!/usr/bin/env zsh
+
+while read -r code
+do
+  print -v unescaped "$code"
+  eval "$unescaped"
+  print "\U10ACDC" | tee /dev/stderr
+done < "${1:-/dev/stdin}"

rust/kernels/Cargo.toml

@@ -32,4 +32,5 @@ kernel-node = { path = "../kernel-node", version = "0.0.0", optional = true }
 kernel-python = { path = "../kernel-python", version = "0.0.0", optional = true }
 kernel-r = { path = "../kernel-r", version = "0.0.0", optional = true }
 kernel-store = { path = "../kernel-store", version = "0.0.0", optional = true }
+kernel-zsh = { path = "../kernel-zsh", version = "0.0.0", optional = true }
 slug = "0.1.4"

rust/kernels/src/lib.rs

@@ -127,6 +127,7 @@ impl MetaKernel {
         microkernel_new!("kernel-node", kernel_node, &selector);
         microkernel_new!("kernel-python", kernel_python, &selector);
         microkernel_new!("kernel-r", kernel_r, &selector);
+        microkernel_new!("kernel-zsh", kernel_zsh, &selector);
 
         bail!(
             "Unable to create an execution kernel for selector `{}`",
@@ -542,6 +543,7 @@ pub async fn available() -> Result<Vec<Kernel>> {
     microkernel_available!("kernel-node", kernel_node, available);
     microkernel_available!("kernel-python", kernel_python, available);
     microkernel_available!("kernel-r", kernel_r, available);
+    microkernel_available!("kernel-zsh", kernel_zsh, available);
 
     Ok(available)
 }

rust/stencila/Cargo.toml

@@ -75,6 +75,7 @@ default = [
   "kernels/kernel-python",
   "kernels/kernel-r",
   "kernels/kernel-store",
+  "kernels/kernel-zsh",
 
   # Binaries
   "binaries/cli",