Add regression test for merged doctests compilation time display

Author: GuillaumeGomez

tests/run-make/doctests-compilation-time-info/rmake.rs

@@ -0,0 +1,119 @@
+//@ ignore-cross-compile (needs to run doctests)
+
+use run_make_support::rfs::write;
+use run_make_support::{cwd, rustdoc};
+
+fn check_present_of_compilation_time_report(
+    content: &str,
+    success: bool,
+    should_contain_compile_time: bool,
+) {
+    let mut cmd = rustdoc();
+    let file = cwd().join("foo.rs");
+
+    write(&file, content);
+    cmd.input(&file).arg("--test").edition("2024").env("RUST_BACKTRACE", "0");
+    let output = if success { cmd.run() } else { cmd.run_fail() };
+
+    assert_eq!(
+        output
+            .stdout_utf8()
+            .split("all doctests ran in ")
+            .last()
+            .is_some_and(|s| s.contains("; merged doctests compilation took")),
+        should_contain_compile_time,
+    );
+}
+
+fn main() {
+    // Checking with only successful merged doctests.
+    check_present_of_compilation_time_report(
+        "\
+//! ```
+//! let x = 12;
+//! ```",
+        true,
+        true,
+    );
+    // Checking with only fainling merged doctests.
+    check_present_of_compilation_time_report(
+        "\
+//! ```
+//! panic!();
+//! ```",
+        false,
+        true,
+    );
+    // Checking with mix of successful doctests.
+    check_present_of_compilation_time_report(
+        "\
+//! ```
+//! let x = 12;
+//! ```
+//!
+//! ```compile_fail
+//! let x
+//! ```",
+        true,
+        true,
+    );
+    // Checking with mix of failing doctests.
+    check_present_of_compilation_time_report(
+        "\
+//! ```
+//! panic!();
+//! ```
+//!
+//! ```compile_fail
+//! let x
+//! ```",
+        false,
+        true,
+    );
+    // Checking with mix of failing doctests (v2).
+    check_present_of_compilation_time_report(
+        "\
+//! ```
+//! let x = 12;
+//! ```
+//!
+//! ```compile_fail
+//! let x = 12;
+//! ```",
+        false,
+        true,
+    );
+    // Checking with mix of failing doctests (v3).
+    check_present_of_compilation_time_report(
+        "\
+//! ```
+//! panic!();
+//! ```
+//!
+//! ```compile_fail
+//! let x = 12;
+//! ```",
+        false,
+        true,
+    );
+    // Checking with successful non-merged doctests.
+    check_present_of_compilation_time_report(
+        "\
+//! ```compile_fail
+//! let x
+//! ```",
+        true,
+        // If there is no merged doctests, then we should not display compilation time.
+        false,
+    );
+    // Checking with failing non-merged doctests.
+    check_present_of_compilation_time_report(
+        "\
+//! ```compile_fail
+//! let x = 12;
+//! ```",
+        false,
+        // If there is no merged doctests, then we should not display compilation time.
+        false,
+    );
+}