echo: do not infer long args

src/uu/echo/src/echo.rs

@@ -132,13 +132,15 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
 }
 
 pub fn uu_app() -> Command {
+    // Note: echo is different from the other utils in that it should **not**
+    // have `infer_long_args(true)`, because, for example, `--ver` should be
+    // printed as `--ver` and not show the version text.
     Command::new(uucore::util_name())
         // TrailingVarArg specifies the final positional argument is a VarArg
         // and it doesn't attempts the parse any further args.
         // Final argument must have multiple(true) or the usage string equivalent.
         .trailing_var_arg(true)
         .allow_hyphen_values(true)
-        .infer_long_args(true)
         .version(crate_version!())
         .about(ABOUT)
         .after_help(AFTER_HELP)

tests/by-util/test_echo.rs

@@ -293,3 +293,13 @@ fn old_octal_syntax() {
         .succeeds()
         .stdout_is("A1\n");
 }
+
+#[test]
+fn partial_version_argument() {
+    new_ucmd!().arg("--ver").succeeds().stdout_is("--ver\n");
+}
+
+#[test]
+fn partial_help_argument() {
+    new_ucmd!().arg("--he").succeeds().stdout_is("--he\n");
+}