diff --git a/src/bootstrap/src/core/build_steps/setup.rs b/src/bootstrap/src/core/build_steps/setup.rs
index dd9c68aba7f7e..5b434eddb7158 100644
--- a/src/bootstrap/src/core/build_steps/setup.rs
+++ b/src/bootstrap/src/core/build_steps/setup.rs
@@ -14,7 +14,6 @@ use std::str::FromStr;
 use std::{fmt, fs, io};
 
 #[cfg(test)]
-#[path = "../../tests/setup.rs"]
 mod tests;
 
 #[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
diff --git a/src/bootstrap/src/tests/setup.rs b/src/bootstrap/src/core/build_steps/setup/tests.rs
similarity index 100%
rename from src/bootstrap/src/tests/setup.rs
rename to src/bootstrap/src/core/build_steps/setup/tests.rs
diff --git a/src/bootstrap/src/core/builder.rs b/src/bootstrap/src/core/builder.rs
index 3770d0687b242..dac8393de6b4c 100644
--- a/src/bootstrap/src/core/builder.rs
+++ b/src/bootstrap/src/core/builder.rs
@@ -32,7 +32,6 @@ use clap::ValueEnum;
 use once_cell::sync::Lazy;
 
 #[cfg(test)]
-#[path = "../tests/builder.rs"]
 mod tests;
 
 pub struct Builder<'a> {
diff --git a/src/bootstrap/src/tests/builder.rs b/src/bootstrap/src/core/builder/tests.rs
similarity index 100%
rename from src/bootstrap/src/tests/builder.rs
rename to src/bootstrap/src/core/builder/tests.rs
diff --git a/src/bootstrap/src/core/config/config.rs b/src/bootstrap/src/core/config/config.rs
index fcdd742e69c22..c0dd1e1208484 100644
--- a/src/bootstrap/src/core/config/config.rs
+++ b/src/bootstrap/src/core/config/config.rs
@@ -3,10 +3,6 @@
 //! This module implements parsing `config.toml` configuration files to tweak
 //! how the build runs.
 
-#[cfg(test)]
-#[path = "../../tests/config.rs"]
-mod tests;
-
 use std::cell::{Cell, RefCell};
 use std::cmp;
 use std::collections::{HashMap, HashSet};
@@ -1203,7 +1199,7 @@ impl Config {
         Self::parse_inner(args, get_toml)
     }
 
-    fn parse_inner(args: &[String], get_toml: impl Fn(&Path) -> TomlConfig) -> Config {
+    pub(crate) fn parse_inner(args: &[String], get_toml: impl Fn(&Path) -> TomlConfig) -> Config {
         let mut flags = Flags::parse(&args);
         let mut config = Config::default_opts();
 
diff --git a/src/bootstrap/src/core/config/mod.rs b/src/bootstrap/src/core/config/mod.rs
index 9c6861826d605..99412848abbb7 100644
--- a/src/bootstrap/src/core/config/mod.rs
+++ b/src/bootstrap/src/core/config/mod.rs
@@ -1,4 +1,6 @@
 pub(crate) mod config;
 pub(crate) mod flags;
+#[cfg(test)]
+mod tests;
 
 pub use config::*;
diff --git a/src/bootstrap/src/tests/config.rs b/src/bootstrap/src/core/config/tests.rs
similarity index 99%
rename from src/bootstrap/src/tests/config.rs
rename to src/bootstrap/src/core/config/tests.rs
index c65067f8e8f76..201d11571c48a 100644
--- a/src/bootstrap/src/tests/config.rs
+++ b/src/bootstrap/src/core/config/tests.rs
@@ -1,4 +1,4 @@
-use super::{Config, Flags};
+use super::{flags::Flags, Config};
 use crate::core::config::{LldMode, TomlConfig};
 
 use clap::CommandFactory;
diff --git a/src/bootstrap/src/utils/change_tracker.rs b/src/bootstrap/src/utils/change_tracker.rs
index 327b4674acfdb..0d5e2600b73a9 100644
--- a/src/bootstrap/src/utils/change_tracker.rs
+++ b/src/bootstrap/src/utils/change_tracker.rs
@@ -2,6 +2,9 @@
 //! with the goal of keeping developers synchronized with important modifications in
 //! the bootstrap.
 
+#[cfg(test)]
+mod tests;
+
 #[derive(Clone, Debug)]
 pub struct ChangeInfo {
     /// Represents the ID of PR caused major change on bootstrap.
diff --git a/src/bootstrap/src/utils/change_tracker/tests.rs b/src/bootstrap/src/utils/change_tracker/tests.rs
new file mode 100644
index 0000000000000..d2bfc07d1727b
--- /dev/null
+++ b/src/bootstrap/src/utils/change_tracker/tests.rs
@@ -0,0 +1,10 @@
+use crate::{find_recent_config_change_ids, CONFIG_CHANGE_HISTORY};
+
+#[test]
+fn test_find_recent_config_change_ids() {
+    // If change-id is greater than the most recent one, result should be empty.
+    assert!(find_recent_config_change_ids(usize::MAX).is_empty());
+
+    // There is no change-id equal to or less than 0, result should include the entire change history.
+    assert_eq!(find_recent_config_change_ids(0).len(), CONFIG_CHANGE_HISTORY.len());
+}
diff --git a/src/bootstrap/src/utils/helpers.rs b/src/bootstrap/src/utils/helpers.rs
index 0c917c3d57933..d1f713af91709 100644
--- a/src/bootstrap/src/utils/helpers.rs
+++ b/src/bootstrap/src/utils/helpers.rs
@@ -21,7 +21,6 @@ use crate::LldMode;
 pub use crate::utils::dylib::{dylib_path, dylib_path_var};
 
 #[cfg(test)]
-#[path = "../tests/helpers.rs"]
 mod tests;
 
 /// A helper macro to `unwrap` a result except also print out details like:
diff --git a/src/bootstrap/src/tests/helpers.rs b/src/bootstrap/src/utils/helpers/tests.rs
similarity index 62%
rename from src/bootstrap/src/tests/helpers.rs
rename to src/bootstrap/src/utils/helpers/tests.rs
index 2d626fad417d7..9cfaa3eb67b5c 100644
--- a/src/bootstrap/src/tests/helpers.rs
+++ b/src/bootstrap/src/utils/helpers/tests.rs
@@ -1,5 +1,14 @@
-use crate::utils::helpers::{check_cfg_arg, extract_beta_rev, hex_encode, make};
-use std::path::PathBuf;
+use crate::{
+    utils::helpers::{
+        check_cfg_arg, extract_beta_rev, hex_encode, make, program_out_of_date, symlink_dir,
+    },
+    Config,
+};
+use std::{
+    fs::{self, remove_file, File},
+    io::Write,
+    path::PathBuf,
+};
 
 #[test]
 fn test_make() {
@@ -70,3 +79,38 @@ fn test_check_cfg_arg() {
         "--check-cfg=cfg(target_os,values(\"nixos\",\"nix2\"))"
     );
 }
+
+#[test]
+fn test_program_out_of_date() {
+    let config = Config::parse(&["check".to_owned(), "--config=/does/not/exist".to_owned()]);
+    let tempfile = config.tempdir().join(".tmp-stamp-file");
+    File::create(&tempfile).unwrap().write_all(b"dummy value").unwrap();
+    assert!(tempfile.exists());
+
+    // up-to-date
+    assert!(!program_out_of_date(&tempfile, "dummy value"));
+    // out-of-date
+    assert!(program_out_of_date(&tempfile, ""));
+
+    remove_file(tempfile).unwrap();
+}
+
+#[test]
+fn test_symlink_dir() {
+    let config = Config::parse(&["check".to_owned(), "--config=/does/not/exist".to_owned()]);
+    let tempdir = config.tempdir().join(".tmp-dir");
+    let link_path = config.tempdir().join(".tmp-link");
+
+    fs::create_dir_all(&tempdir).unwrap();
+    symlink_dir(&config, &tempdir, &link_path).unwrap();
+
+    let link_source = fs::read_link(&link_path).unwrap();
+    assert_eq!(link_source, tempdir);
+
+    fs::remove_dir(tempdir).unwrap();
+
+    #[cfg(windows)]
+    fs::remove_dir(link_path).unwrap();
+    #[cfg(not(windows))]
+    fs::remove_file(link_path).unwrap();
+}