diff --git a/dsp/src/lib.rs b/dsp/src/lib.rs
index ca1daec..389bda5 100644
--- a/dsp/src/lib.rs
+++ b/dsp/src/lib.rs
@@ -5,3 +5,6 @@ pub type Complex<T> = (T, T);
 pub mod iir;
 pub mod lockin;
 pub mod pll;
+
+#[cfg(test)]
+mod testing;
diff --git a/dsp/src/lockin.rs b/dsp/src/lockin.rs
index 66b3a9a..6b6017b 100644
--- a/dsp/src/lockin.rs
+++ b/dsp/src/lockin.rs
@@ -271,60 +271,9 @@ pub fn magnitude_phase(signal: &mut [Complex<f32>]) {
 #[cfg(test)]
 mod tests {
     use super::*;
-
-    fn f32_is_close(a: f32, b: f32) -> bool {
-        (a - b).abs() <= a.abs().max(b.abs()) * f32::EPSILON
-    }
-
-    fn complex_is_close(a: Complex<f32>, b: Complex<f32>) -> bool {
-        f32_is_close(a.0, b.0) && f32_is_close(a.1, b.1)
-    }
-
-    fn complex_array_is_close(a: &[Complex<f32>], b: &[Complex<f32>]) -> bool {
-        let mut result: bool = true;
-        a.iter().zip(b.iter()).for_each(|(i, j)| {
-            result &= complex_is_close(*i, *j);
-        });
-        result
-    }
-
-    fn within_tolerance(
-        a: f32,
-        b: f32,
-        relative_tolerance: f32,
-        fixed_tolerance: f32,
-    ) -> bool {
-        (a - b).abs()
-            <= a.abs().max(b.abs()) * relative_tolerance + fixed_tolerance
-    }
-
-    fn complex_within_tolerance(
-        a: Complex<f32>,
-        b: Complex<f32>,
-        relative_tolerance: f32,
-        fixed_tolerance: f32,
-    ) -> bool {
-        within_tolerance(a.0, b.0, relative_tolerance, fixed_tolerance)
-            && within_tolerance(a.1, b.1, relative_tolerance, fixed_tolerance)
-    }
-
-    fn complex_array_within_tolerance(
-        a: &[Complex<f32>],
-        b: &[Complex<f32>],
-        relative_tolerance: f32,
-        fixed_tolerance: f32,
-    ) -> bool {
-        let mut result: bool = true;
-        a.iter().zip(b.iter()).for_each(|(i, j)| {
-            result &= complex_within_tolerance(
-                *i,
-                *j,
-                relative_tolerance,
-                fixed_tolerance,
-            );
-        });
-        result
-    }
+    use crate::testing::{
+        complex_array_is_close, complex_array_within_tolerance,
+    };
 
     #[test]
     fn array_push() {
diff --git a/dsp/src/testing.rs b/dsp/src/testing.rs
new file mode 100644
index 0000000..0fe9e4f
--- /dev/null
+++ b/dsp/src/testing.rs
@@ -0,0 +1,54 @@
+use super::Complex;
+
+pub fn f32_is_close(a: f32, b: f32) -> bool {
+    (a - b).abs() <= a.abs().max(b.abs()) * f32::EPSILON
+}
+
+pub fn complex_is_close(a: Complex<f32>, b: Complex<f32>) -> bool {
+    f32_is_close(a.0, b.0) && f32_is_close(a.1, b.1)
+}
+
+pub fn complex_array_is_close(a: &[Complex<f32>], b: &[Complex<f32>]) -> bool {
+    let mut result: bool = true;
+    a.iter().zip(b.iter()).for_each(|(i, j)| {
+        result &= complex_is_close(*i, *j);
+    });
+    result
+}
+
+pub fn within_tolerance(
+    a: f32,
+    b: f32,
+    relative_tolerance: f32,
+    fixed_tolerance: f32,
+) -> bool {
+    (a - b).abs() <= a.abs().max(b.abs()) * relative_tolerance + fixed_tolerance
+}
+
+pub fn complex_within_tolerance(
+    a: Complex<f32>,
+    b: Complex<f32>,
+    relative_tolerance: f32,
+    fixed_tolerance: f32,
+) -> bool {
+    within_tolerance(a.0, b.0, relative_tolerance, fixed_tolerance)
+        && within_tolerance(a.1, b.1, relative_tolerance, fixed_tolerance)
+}
+
+pub fn complex_array_within_tolerance(
+    a: &[Complex<f32>],
+    b: &[Complex<f32>],
+    relative_tolerance: f32,
+    fixed_tolerance: f32,
+) -> bool {
+    let mut result: bool = true;
+    a.iter().zip(b.iter()).for_each(|(i, j)| {
+        result &= complex_within_tolerance(
+            *i,
+            *j,
+            relative_tolerance,
+            fixed_tolerance,
+        );
+    });
+    result
+}