feat(cli): `deno init --lib` (#22499)

Closes #22287

Co-authored-by: Asher Gomez <ashersaupingomez@gmail.com>
Co-authored-by: David Sherret <dsherret@gmail.com>

9 files changed, 232 insertions, 68 deletions

diff --git a/cli/args/flags.rs b/cli/args/flags.rs
index 89f53d593..d2321f32e 100644
--- a/cli/args/flags.rs
+++ b/cli/args/flags.rs
@@ -205,6 +205,7 @@ impl FmtFlags {
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub struct InitFlags {
   pub dir: Option<String>,
+  pub lib: bool,
 }
 
 #[derive(Clone, Debug, Eq, PartialEq)]
@@ -2052,11 +2053,18 @@ fn init_subcommand() -> Command {
   Command::new("init")
     .about("Initialize a new project")
     .defer(|cmd| {
-      cmd.arg(
-        Arg::new("dir")
-          .required(false)
-          .value_hint(ValueHint::DirPath),
-      )
+      cmd
+        .arg(
+          Arg::new("dir")
+            .required(false)
+            .value_hint(ValueHint::DirPath),
+        )
+        .arg(
+          Arg::new("lib")
+            .long("lib")
+            .required(false)
+            .action(ArgAction::SetTrue),
+        )
     })
 }
 
@@ -4033,6 +4041,7 @@ fn fmt_parse(flags: &mut Flags, matches: &mut ArgMatches) {
 fn init_parse(flags: &mut Flags, matches: &mut ArgMatches) {
   flags.subcommand = DenoSubcommand::Init(InitFlags {
     dir: matches.remove_one::<String>("dir"),
+    lib: matches.get_flag("lib"),
   });
 }
 
@@ -9753,7 +9762,10 @@ mod tests {
     assert_eq!(
       r.unwrap(),
       Flags {
-        subcommand: DenoSubcommand::Init(InitFlags { dir: None }),
+        subcommand: DenoSubcommand::Init(InitFlags {
+          dir: None,
+          lib: false
+        }),
         ..Flags::default()
       }
     );
@@ -9764,6 +9776,7 @@ mod tests {
       Flags {
         subcommand: DenoSubcommand::Init(InitFlags {
           dir: Some(String::from("foo")),
+          lib: false
         }),
         ..Flags::default()
       }
@@ -9773,11 +9786,38 @@ mod tests {
     assert_eq!(
       r.unwrap(),
       Flags {
-        subcommand: DenoSubcommand::Init(InitFlags { dir: None }),
+        subcommand: DenoSubcommand::Init(InitFlags {
+          dir: None,
+          lib: false
+        }),
         log_level: Some(Level::Error),
         ..Flags::default()
       }
     );
+
+    let r = flags_from_vec(svec!["deno", "init", "--lib"]);
+    assert_eq!(
+      r.unwrap(),
+      Flags {
+        subcommand: DenoSubcommand::Init(InitFlags {
+          dir: None,
+          lib: true
+        }),
+        ..Flags::default()
+      }
+    );
+
+    let r = flags_from_vec(svec!["deno", "init", "foo", "--lib"]);
+    assert_eq!(
+      r.unwrap(),
+      Flags {
+        subcommand: DenoSubcommand::Init(InitFlags {
+          dir: Some(String::from("foo")),
+          lib: true
+        }),
+        ..Flags::default()
+      }
+    );
   }
 
   #[test]
diff --git a/cli/tools/init/mod.rs b/cli/tools/init/mod.rs
index fb2e6e7af..23b14e17c 100644
--- a/cli/tools/init/mod.rs
+++ b/cli/tools/init/mod.rs
@@ -4,33 +4,11 @@ use crate::args::InitFlags;
 use crate::colors;
 use deno_core::anyhow::Context;
 use deno_core::error::AnyError;
+use deno_core::serde_json::json;
 use log::info;
 use std::io::Write;
 use std::path::Path;
 
-fn create_file(
-  dir: &Path,
-  filename: &str,
-  content: &str,
-) -> Result<(), AnyError> {
-  let path = dir.join(filename);
-  if path.exists() {
-    info!(
-      "ℹ️ {}",
-      colors::gray(format!("Skipped creating {filename} as it already exists"))
-    );
-    Ok(())
-  } else {
-    let mut file = std::fs::OpenOptions::new()
-      .write(true)
-      .create_new(true)
-      .open(path)
-      .with_context(|| format!("Failed to create {filename} file"))?;
-    file.write_all(content.as_bytes())?;
-    Ok(())
-  }
-}
-
 pub fn init_project(init_flags: InitFlags) -> Result<(), AnyError> {
   let cwd =
     std::env::current_dir().context("Can't read current working directory.")?;
@@ -42,15 +20,82 @@ pub fn init_project(init_flags: InitFlags) -> Result<(), AnyError> {
     cwd
   };
 
-  let main_ts = include_str!("./templates/main.ts");
-  create_file(&dir, "main.ts", main_ts)?;
+  if init_flags.lib {
+    // Extract the directory name to use as the project name
+    let project_name = dir
+      .file_name()
+      .unwrap_or_else(|| dir.as_os_str())
+      .to_str()
+      .unwrap();
+
+    create_file(
+      &dir,
+      "mod.ts",
+      r#"export function add(a: number, b: number): number {
+  return a + b;
+}
+"#,
+    )?;
+    create_file(
+      &dir,
+      "mod_test.ts",
+      r#"import { assertEquals } from "jsr:@std/assert";
+import { add } from "./mod.ts";
+
+Deno.test(function addTest() {
+  assertEquals(add(2, 3), 5);
+});
+"#,
+    )?;
+
+    create_json_file(
+      &dir,
+      "deno.json",
+      &json!({
+        "name": project_name,
+        "version": "1.0.0",
+        "exports": "./mod.ts",
+        "tasks": {
+          "dev": "deno test --watch mod.ts"
+        }
+      }),
+    )?;
+  } else {
+    create_file(
+      &dir,
+      "main.ts",
+      r#"export function add(a: number, b: number): number {
+  return a + b;
+}
+
+// Learn more at https://deno.land/manual/examples/module_metadata#concepts
+if (import.meta.main) {
+  console.log("Add 2 + 3 =", add(2, 3));
+}
+"#,
+    )?;
+    create_file(
+      &dir,
+      "main_test.ts",
+      r#"import { assertEquals } from "jsr:@std/assert";
+import { add } from "./main.ts";
 
-  create_file(
-    &dir,
-    "main_test.ts",
-    include_str!("./templates/main_test.ts"),
-  )?;
-  create_file(&dir, "deno.json", include_str!("./templates/deno.json"))?;
+Deno.test(function addTest() {
+  assertEquals(add(2, 3), 5);
+});
+"#,
+    )?;
+
+    create_json_file(
+      &dir,
+      "deno.json",
+      &json!({
+        "tasks": {
+          "dev": "deno run --watch main.ts"
+        }
+      }),
+    )?;
+  }
 
   info!("✅ {}", colors::green("Project initialized"));
   info!("");
@@ -60,16 +105,63 @@ pub fn init_project(init_flags: InitFlags) -> Result<(), AnyError> {
     info!("  cd {}", dir);
     info!("");
   }
-  info!("  {}", colors::gray("# Run the program"));
-  info!("  deno run main.ts");
-  info!("");
-  info!(
-    "  {}",
-    colors::gray("# Run the program and watch for file changes")
-  );
-  info!("  deno task dev");
-  info!("");
-  info!("  {}", colors::gray("# Run the tests"));
-  info!("  deno test");
+  if init_flags.lib {
+    info!("  {}", colors::gray("# Run the tests"));
+    info!("  deno test");
+    info!("");
+    info!(
+      "  {}",
+      colors::gray("# Run the tests and watch for file changes")
+    );
+    info!("  deno task dev");
+    info!("");
+    info!("  {}", colors::gray("# Publish to JSR (dry run)"));
+    info!("  deno publish --dry-run");
+  } else {
+    info!("  {}", colors::gray("# Run the program"));
+    info!("  deno run main.ts");
+    info!("");
+    info!(
+      "  {}",
+      colors::gray("# Run the program and watch for file changes")
+    );
+    info!("  deno task dev");
+    info!("");
+    info!("  {}", colors::gray("# Run the tests"));
+    info!("  deno test");
+  }
   Ok(())
 }
+
+fn create_json_file(
+  dir: &Path,
+  filename: &str,
+  value: &deno_core::serde_json::Value,
+) -> Result<(), AnyError> {
+  let mut text = deno_core::serde_json::to_string_pretty(value)?;
+  text.push('\n');
+  create_file(dir, filename, &text)
+}
+
+fn create_file(
+  dir: &Path,
+  filename: &str,
+  content: &str,
+) -> Result<(), AnyError> {
+  let path = dir.join(filename);
+  if path.exists() {
+    info!(
+      "ℹ️ {}",
+      colors::gray(format!("Skipped creating {filename} as it already exists"))
+    );
+    Ok(())
+  } else {
+    let mut file = std::fs::OpenOptions::new()
+      .write(true)
+      .create_new(true)
+      .open(path)
+      .with_context(|| format!("Failed to create {filename} file"))?;
+    file.write_all(content.as_bytes())?;
+    Ok(())
+  }
+}
diff --git a/cli/tools/init/templates/deno.json b/cli/tools/init/templates/deno.json
deleted file mode 100644
index 3c5130f1d..000000000
--- a/cli/tools/init/templates/deno.json
+++ /dev/null
@@ -1,5 +0,0 @@
-{
-  "tasks": {
-    "dev": "deno run --watch main.ts"
-  }
-}
diff --git a/cli/tools/init/templates/main.ts b/cli/tools/init/templates/main.ts
deleted file mode 100644
index be043e97c..000000000
--- a/cli/tools/init/templates/main.ts
+++ /dev/null
@@ -1,8 +0,0 @@
-export function add(a: number, b: number): number {
-  return a + b;
-}
-
-// Learn more at https://deno.land/manual/examples/module_metadata#concepts
-if (import.meta.main) {
-  console.log("Add 2 + 3 =", add(2, 3));
-}
diff --git a/cli/tools/init/templates/main_test.ts b/cli/tools/init/templates/main_test.ts
deleted file mode 100644
index 26af2582b..000000000
--- a/cli/tools/init/templates/main_test.ts
+++ /dev/null
@@ -1,6 +0,0 @@
-import { assertEquals } from "jsr:@std/assert";
-import { add } from "./main.ts";
-
-Deno.test(function addTest() {
-  assertEquals(add(2, 3), 5);
-});
diff --git a/tests/specs/init/lib/__test__.jsonc b/tests/specs/init/lib/__test__.jsonc
new file mode 100644
index 000000000..076930ae6
--- /dev/null
+++ b/tests/specs/init/lib/__test__.jsonc
@@ -0,0 +1,16 @@
+{
+  "tempDir": true,
+  "steps": [{
+    "args": "init --lib project",
+    "output": "init.out"
+  }, {
+    "cwd": "project",
+    "args": "test",
+    "output": "test.out"
+  }, {
+    "cwd": "project",
+    "args": "publish --dry-run",
+    "output": "dry_publish.out",
+    "exitCode": 1
+  }]
+}
diff --git a/tests/specs/init/lib/dry_publish.out b/tests/specs/init/lib/dry_publish.out
new file mode 100644
index 000000000..31f91c38d
--- /dev/null
+++ b/tests/specs/init/lib/dry_publish.out
@@ -0,0 +1,7 @@
+Check file:///[WILDLINE]/mod.ts
+Checking for slow types in the public API...
+Check file:///[WILDLINE]/mod.ts
+error: Failed preparing 'project'.
+
+Caused by:
+    Invalid package name, use '@<scope_name>/<package_name> format
diff --git a/tests/specs/init/lib/init.out b/tests/specs/init/lib/init.out
new file mode 100644
index 000000000..0f1a83f30
--- /dev/null
+++ b/tests/specs/init/lib/init.out
@@ -0,0 +1,14 @@
+✅ Project initialized
+
+Run these commands to get started
+
+  cd project
+
+  # Run the tests
+  deno test
+
+  # Run the tests and watch for file changes
+  deno task dev
+
+  # Publish to JSR (dry run)
+  deno publish --dry-run
diff --git a/tests/specs/init/lib/test.out b/tests/specs/init/lib/test.out
new file mode 100644
index 000000000..0b225a52b
--- /dev/null
+++ b/tests/specs/init/lib/test.out
@@ -0,0 +1,14 @@
+Download http://127.0.0.1:4250/@std/assert/meta.json
+Download http://127.0.0.1:4250/@std/assert/0.220.1_meta.json
+[UNORDERED_START]
+Download http://127.0.0.1:4250/@std/assert/0.220.1/mod.ts
+Download http://127.0.0.1:4250/@std/assert/0.220.1/assert_equals.ts
+Download http://127.0.0.1:4250/@std/assert/0.220.1/assert.ts
+Download http://127.0.0.1:4250/@std/assert/0.220.1/fail.ts
+[UNORDERED_END]
+Check file:///[WILDLINE]/mod_test.ts
+running 1 test from ./mod_test.ts
+addTest ... ok ([WILDLINE])
+
+ok | 1 passed | 0 failed ([WILDLINE])
+