Add tests for multiple build scripts execution

tests/testsuite/build_scripts_multiple.rs

@@ -409,6 +409,205 @@ path = "src/main.rs"
         .run();
 }
 
+#[cargo_test]
+fn custom_build_script_first_index_script_failed() {
+    // In this, the script that is at first index in the build script array fails
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                cargo-features = ["multiple-build-scripts"]
+
+                [package]
+                name = "foo"
+                version = "0.1.0"
+                edition = "2024"
+
+                build = ["build1.rs", "build2.rs"]
+            "#,
+        )
+        .file("src/main.rs", "fn main() {}")
+        .file("build1.rs", "fn main() { std::process::exit(101); }")
+        .file("build2.rs", "fn main() {}")
+        .build();
+
+    p.cargo("check -v")
+        .masquerade_as_nightly_cargo(&["multiple-build-scripts"])
+        .with_status(101)
+        .with_stderr_data(str![[r#"
+[COMPILING] foo v0.1.0 ([ROOT]/foo)
+[RUNNING] `rustc --crate-name build_script_build1 --edition=2024 build1.rs [..]--crate-type bin [..]`
+[RUNNING] `[ROOT]/foo/target/debug/build/foo-[HASH]/build-script-build1`
+[ERROR] failed to run custom build command for `foo v0.1.0 ([ROOT]/foo)`
+
+Caused by:
+  process didn't exit successfully: `[ROOT]/foo/target/debug/build/foo-[HASH]/build-script-build1` ([EXIT_STATUS]: 101)
+
+"#]])
+        .run();
+}
+
+#[cargo_test]
+fn custom_build_script_second_index_script_failed() {
+    // In this, the script that is at second index in the build script array fails
+    // This test was necessary because earlier, the program failed only if first script failed.
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                cargo-features = ["multiple-build-scripts"]
+
+                [package]
+                name = "foo"
+                version = "0.1.0"
+                edition = "2024"
+
+                build = ["build1.rs", "build2.rs"]
+            "#,
+        )
+        .file("src/main.rs", "fn main() {}")
+        .file("build1.rs", "fn main() {}")
+        .file("build2.rs", "fn main() { std::process::exit(101); }")
+        .build();
+
+    p.cargo("check -v")
+        .masquerade_as_nightly_cargo(&["multiple-build-scripts"])
+        .with_status(0)
+        .with_stderr_data(str![[r#"
+[COMPILING] foo v0.1.0 ([ROOT]/foo)
+[RUNNING] `rustc --crate-name build_script_build1 --edition=2024 build1.rs [..]--crate-type bin [..]`
+[RUNNING] `[ROOT]/foo/target/debug/build/foo-[HASH]/build-script-build1`
+[RUNNING] `rustc --crate-name foo --edition=2024 src/main.rs [..] --crate-type bin [..]`
+[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
+
+"#]])
+        .run();
+}
+
+#[cargo_test]
+fn build_script_with_conflicting_environment_variables() {
+    // In this, multiple scripts set different values to same environment variables
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                cargo-features = ["multiple-build-scripts"]
+
+                [package]
+                name = "foo"
+                version = "0.1.0"
+                edition = "2024"
+
+                build = ["build1.rs", "build2.rs"]
+            "#,
+        )
+        .file(
+            "src/main.rs",
+            r#"
+                const FOO: &'static str = env!("FOO");
+                fn main() {
+                    println!("{}", FOO);
+                }
+            "#,
+        )
+        .file(
+            "build1.rs",
+            r#"fn main() { println!("cargo::rustc-env=FOO=bar1"); }"#,
+        )
+        .file(
+            "build2.rs",
+            r#"fn main() { println!("cargo::rustc-env=FOO=bar2"); }"#,
+        )
+        .build();
+
+    p.cargo("run -v")
+        .masquerade_as_nightly_cargo(&["multiple-build-scripts"])
+        .with_status(0)
+        .with_stdout_data(str![[r#"
+bar1
+
+"#]])
+        .run();
+}
+
+#[cargo_test]
+fn build_script_with_conflicting_out_dirs() {
+    // In this, multiple scripts create file with same name in their respective OUT_DIR.
+
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                cargo-features = ["multiple-build-scripts"]
+
+                [package]
+                name = "foo"
+                version = "0.1.0"
+                edition = "2024"
+
+                build = ["build1.rs", "build2.rs"]
+            "#,
+        )
+        // OUT_DIR is set to the lexicographically largest build script's OUT_DIR by default
+        .file(
+            "src/main.rs",
+            r#"
+                include!(concat!(env!("OUT_DIR"), "/foo.rs"));
+                fn main() {
+                    println!("{}", message());
+                }
+            "#,
+        )
+        .file(
+            "build1.rs",
+            r#"
+            use std::env;
+            use std::fs;
+            use std::path::Path;
+
+            fn main() {
+                let out_dir = env::var_os("OUT_DIR").unwrap();
+                let dest_path = Path::new(&out_dir).join("foo.rs");
+                fs::write(
+                    &dest_path,
+                    "pub fn message() -> &'static str {
+                        \"Hello, from Build Script 1!\"
+                    }
+                    "
+                ).unwrap();
+             }"#,
+        )
+        .file(
+            "build2.rs",
+            r#"
+            use std::env;
+            use std::fs;
+            use std::path::Path;
+
+            fn main() {
+                let out_dir = env::var_os("OUT_DIR").unwrap();
+                let dest_path = Path::new(&out_dir).join("foo.rs");
+                fs::write(
+                    &dest_path,
+                    "pub fn message() -> &'static str {
+                        \"Hello, from Build Script 2!\"
+                    }
+                    "
+                ).unwrap();
+             }"#,
+        )
+        .build();
+
+    p.cargo("run -v")
+        .masquerade_as_nightly_cargo(&["multiple-build-scripts"])
+        .with_status(0)
+        .with_stdout_data(str![[r#"
+Hello, from Build Script 1!
+
+"#]])
+        .run();
+}
+
 #[cargo_test]
 fn rerun_untracks_other_files() {
     let p = project()