Logs and tests (#3247)

* Add command name to err

* Add var name to error message

* Add test for def comment in test

crates/nu-parser/tests/main.rs

@@ -0,0 +1,25 @@
+use nu_test_support::fs::Stub::FileWithContent;
+use nu_test_support::nu;
+use nu_test_support::playground::Playground;
+
+#[test]
+fn defs_contain_comment_in_help() {
+    Playground::setup("comment_test", |dirs, sandbox| {
+        sandbox.with_files(vec![FileWithContent(
+            "my_def.nu",
+            r#"
+                # I comment and test. I am a good boy.
+                def comment_philosphy [] {
+                    echo It’s not a bug – it’s an undocumented feature. (Anonymous)
+                }
+                "#,
+        )]);
+
+        let actual = nu!(cwd: dirs.test(), r#"
+            source my_def.nu
+            help comment_philosphy
+            "#);
+
+        assert!(actual.out.contains("I comment and test. I am a good boy."));
+    });
+}