Port `run-make/libtest-json/validate_json.py` to Rust

This is a trivial Python script that simply tries to parse each line of stdin
(i.e. the test process output) as JSON, to verify that the overall output is
JSON Lines.

We can perform the same check directly in `rmake.rs` using `serde_json`.

2 files changed, 13 insertions, 10 deletions

diff --git a/tests/run-make/libtest-json/rmake.rs b/tests/run-make/libtest-json/rmake.rs
index acbd88dc46c..c31f4a79b64 100644
--- a/tests/run-make/libtest-json/rmake.rs
+++ b/tests/run-make/libtest-json/rmake.rs
@@ -3,7 +3,7 @@
 //@ ignore-cross-compile
 //@ needs-unwind (test file contains #[should_panic] test)
 
-use run_make_support::{cmd, diff, python_command, rustc};
+use run_make_support::{cmd, diff, rustc, serde_json};
 
 fn main() {
     rustc().arg("--test").input("f.rs").run();
@@ -21,7 +21,18 @@ fn run_tests(extra_args: &[&str], expected_file: &str) {
         .run_fail();
     let test_stdout = &cmd_out.stdout_utf8();
 
-    python_command().arg("validate_json.py").stdin(test_stdout).run();
+    // Verify that the test process output is JSON Lines, i.e. each line is valid JSON.
+    for (line, n) in test_stdout.lines().zip(1..) {
+        if let Err(e) = serde_json::from_str::<serde_json::Value>(line) {
+            panic!(
+                "could not parse JSON on line {n}: {e}\n\
+                \n\
+                === STDOUT ===\n\
+                {test_stdout}\
+                =============="
+            );
+        }
+    }
 
     diff()
         .expected_file(expected_file)
diff --git a/tests/run-make/libtest-json/validate_json.py b/tests/run-make/libtest-json/validate_json.py
deleted file mode 100755
index 657f732f2bf..00000000000
--- a/tests/run-make/libtest-json/validate_json.py
+++ /dev/null
@@ -1,8 +0,0 @@
-#!/usr/bin/env python
-
-import sys
-import json
-
-# Try to decode line in order to ensure it is a valid JSON document
-for line in sys.stdin:
-    json.loads(line)