Allow main command to define top-level module command (#7764)

crates/nu-command/src/core_commands/help_modules.rs

@@ -151,15 +151,11 @@ pub fn help_modules(
         long_desc.push_str(&format!("{G}Module{RESET}: {C}{name}{RESET}"));
         long_desc.push_str("\n\n");
 
-        if !module.decls.is_empty() {
+        if !module.decls.is_empty() || module.main.is_some() {
             let commands: Vec<(Vec<u8>, DeclId)> = engine_state.get_decls_sorted(false).collect();
 
-            let mut module_commands: Vec<(&[u8], DeclId)> = module
-                .decls
-                .iter()
-                .map(|(name, id)| (name.as_ref(), *id))
-                .collect();
-            module_commands.sort_by(|a, b| a.0.cmp(b.0));
+            let mut module_commands = module.decls();
+            module_commands.sort_by(|a, b| a.0.cmp(&b.0));
 
             let commands_str = module_commands
                 .iter()

crates/nu-command/src/system/nu_check.rs

@@ -302,12 +302,14 @@ fn parse_module(
     is_debug: bool,
     span: Span,
 ) -> Result<PipelineData, ShellError> {
+    let filename = filename.unwrap_or_else(|| "empty".to_string());
+
     let start = working_set.next_span_start();
-    working_set.add_file(filename.unwrap_or_else(|| "empty".to_string()), contents);
+    working_set.add_file(filename.clone(), contents);
     let end = working_set.next_span_start();
 
     let new_span = Span::new(start, end);
-    let (_, _, _, err) = parse_module_block(working_set, new_span, &[]);
+    let (_, _, _, err) = parse_module_block(working_set, new_span, filename.as_bytes(), &[]);
 
     if err.is_some() {
         if is_debug {

crates/nu-command/tests/commands/help.rs

@@ -314,3 +314,31 @@ fn help_usage_extra_usage() {
         assert!(!actual.out.contains("alias_line2"));
     })
 }
+
+#[test]
+fn help_modules_main_1() {
+    let inp = &[
+        r#"module spam {
+            export def main [] { 'foo' };
+        }"#,
+        "help spam",
+    ];
+
+    let actual = nu!(cwd: ".", pipeline(&inp.join("; ")));
+
+    assert!(actual.out.contains("  spam"));
+}
+
+#[test]
+fn help_modules_main_2() {
+    let inp = &[
+        r#"module spam {
+            export def main [] { 'foo' };
+        }"#,
+        "help modules | where name == spam | get 0.commands.0",
+    ];
+
+    let actual = nu!(cwd: ".", pipeline(&inp.join("; ")));
+
+    assert_eq!(actual.out, "spam");
+}

crates/nu-command/tests/commands/use_.rs

@@ -211,3 +211,96 @@ fn use_module_creates_accurate_did_you_mean_2() {
         "command 'foo' was not found but it exists in module 'spam'; try importing it with `use`"
     ));
 }
+
+#[test]
+fn use_main_1() {
+    let inp = &[
+        r#"module spam { export def main [] { "spam" } }"#,
+        r#"use spam"#,
+        r#"spam"#,
+    ];
+
+    let actual = nu!(cwd: ".", pipeline(&inp.join("; ")));
+
+    assert_eq!(actual.out, "spam");
+}
+
+#[test]
+fn use_main_2() {
+    let inp = &[
+        r#"module spam { export def main [] { "spam" } }"#,
+        r#"use spam main"#,
+        r#"spam"#,
+    ];
+
+    let actual = nu!(cwd: ".", pipeline(&inp.join("; ")));
+
+    assert_eq!(actual.out, "spam");
+}
+
+#[test]
+fn use_main_3() {
+    let inp = &[
+        r#"module spam { export def main [] { "spam" } }"#,
+        r#"use spam [ main ]"#,
+        r#"spam"#,
+    ];
+
+    let actual = nu!(cwd: ".", pipeline(&inp.join("; ")));
+
+    assert_eq!(actual.out, "spam");
+}
+
+#[test]
+fn use_main_4() {
+    let inp = &[
+        r#"module spam { export def main [] { "spam" } }"#,
+        r#"use spam *"#,
+        r#"spam"#,
+    ];
+
+    let actual = nu!(cwd: ".", pipeline(&inp.join("; ")));
+
+    assert_eq!(actual.out, "spam");
+}
+
+#[test]
+fn use_main_def_env() {
+    let inp = &[
+        r#"module spam { export def-env main [] { let-env SPAM = "spam" } }"#,
+        r#"use spam"#,
+        r#"spam"#,
+        r#"$env.SPAM"#,
+    ];
+
+    let actual = nu!(cwd: ".", pipeline(&inp.join("; ")));
+
+    assert_eq!(actual.out, "spam");
+}
+
+#[test]
+fn use_main_def_known_external() {
+    // note: requires installed cargo
+    let inp = &[
+        r#"module cargo { export extern main [] }"#,
+        r#"use cargo"#,
+        r#"cargo --version"#,
+    ];
+
+    let actual = nu!(cwd: ".", pipeline(&inp.join("; ")));
+
+    assert!(actual.out.contains("cargo"));
+}
+
+#[test]
+fn use_main_not_exported() {
+    let inp = &[
+        r#"module spam { def main [] { "spam" } }"#,
+        r#"use spam"#,
+        r#"spam"#,
+    ];
+
+    let actual = nu!(cwd: ".", pipeline(&inp.join("; ")));
+
+    assert!(actual.err.contains("external_command"));
+}