Port run-make/libtest-json to rmake

Author: Zalathar

Diff for: src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -9,7 +9,6 @@ run-make/incr-add-rust-src-component/Makefile
 run-make/issue-84395-lto-embed-bitcode/Makefile
 run-make/jobserver-error/Makefile
 run-make/libs-through-symlinks/Makefile
-run-make/libtest-json/Makefile
 run-make/libtest-junit/Makefile
 run-make/libtest-thread-limit/Makefile
 run-make/macos-deployment-target/Makefile

Diff for: tests/run-make/libtest-json/Makefile

@@ -7,4 +7,4 @@
 { "type": "test", "name": "c", "event": "ok" }
 { "type": "test", "event": "started", "name": "d" }
 { "type": "test", "name": "d", "event": "ignored", "message": "msg" }
-{ "type": "suite", "event": "failed", "passed": 2, "failed": 1, "ignored": 1, "measured": 0, "filtered_out": 0, "exec_time": $TIME }
+{ "type": "suite", "event": "failed", "passed": 2, "failed": 1, "ignored": 1, "measured": 0, "filtered_out": 0, "exec_time": "$EXEC_TIME" }

Diff for: tests/run-make/libtest-json/output-default.json

@@ -7,4 +7,4 @@
 { "type": "test", "name": "c", "event": "ok", "stdout": "thread 'c' panicked at f.rs:15:5:\nassertion failed: false\n" }
 { "type": "test", "event": "started", "name": "d" }
 { "type": "test", "name": "d", "event": "ignored", "message": "msg" }
-{ "type": "suite", "event": "failed", "passed": 2, "failed": 1, "ignored": 1, "measured": 0, "filtered_out": 0, "exec_time": $TIME }
+{ "type": "suite", "event": "failed", "passed": 2, "failed": 1, "ignored": 1, "measured": 0, "filtered_out": 0, "exec_time": "$EXEC_TIME" }

Diff for: tests/run-make/libtest-json/output-stdout-success.json

@@ -0,0 +1,31 @@
+// Check libtest's JSON output against snapshots.
+
+//@ ignore-cross-compile
+//@ needs-unwind (test file contains #[should_panic] test)
+
+use run_make_support::{cmd, diff, python_command, rustc};
+
+fn main() {
+    rustc().arg("--test").input("f.rs").run();
+
+    run_tests(&[], "output-default.json");
+    run_tests(&["--show-output"], "output-stdout-success.json");
+}
+
+#[track_caller]
+fn run_tests(extra_args: &[&str], expected_file: &str) {
+    let cmd_out = cmd("./f")
+        .env("RUST_BACKTRACE", "0")
+        .args(&["-Zunstable-options", "--test-threads=1", "--format=json"])
+        .args(extra_args)
+        .run_fail();
+    let test_stdout = &cmd_out.stdout_utf8();
+
+    python_command().arg("validate_json.py").stdin(test_stdout).run();
+
+    diff()
+        .expected_file(expected_file)
+        .actual_text("stdout", test_stdout)
+        .normalize(r#"(?<prefix>"exec_time": )[0-9.]+"#, r#"${prefix}"$$EXEC_TIME""#)
+        .run();
+}