diff --git a/src/args.rs b/src/args.rs
index 336be67..1ac3ad2 100644
--- a/src/args.rs
+++ b/src/args.rs
@@ -1,5 +1,3 @@
-use std::path::PathBuf;
-
 use clap::Parser;
 
 #[derive(Parser, Debug)]
diff --git a/src/main.rs b/src/main.rs
index a8abacf..3be6cd6 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,17 +1,13 @@
 use args::Args;
 use clap::Parser;
 use codespan_reporting::{
-    files::{SimpleFile, SimpleFiles},
+    files::SimpleFiles,
     term::{
         self,
         termcolor::{ColorChoice, StandardStream},
     },
 };
-use syntax::{
-    check::{self, check},
-    error::SyntaxError,
-    parse_syntax, PipelineElement,
-};
+use syntax::{check::check, error::SyntaxError, parse_syntax};
 
 mod args;
 mod builtins;
diff --git a/src/syntax/check.rs b/src/syntax/check.rs
index c69f950..dd074cb 100644
--- a/src/syntax/check.rs
+++ b/src/syntax/check.rs
@@ -1,22 +1,20 @@
-use super::{
-    error::{FileId, SyntaxError},
-    parse_syntax, PipelineElement, PipelineElementKind,
-};
+#[cfg(test)]
+mod test;
 
-pub fn check(
-    syntax: &Vec<PipelineElement>,
-) -> Result<(), Vec<SyntaxError>> {
+use super::{error::SyntaxError, PipelineElement, PipelineElementKind};
+
+pub fn check(syntax: &[PipelineElement]) -> Result<(), Vec<SyntaxError>> {
     let mut errs = Vec::new();
 
-    if let Err(e_span) = check_missing_streamer(&syntax) {
+    if let Err(e_span) = check_missing_streamer(syntax) {
         errs.push(SyntaxError::MissingStreamer(vec![e_span]));
     }
 
-    if let Err(err_locs) = check_missing_filters(&syntax) {
+    if let Err(err_locs) = check_missing_filters(syntax) {
         errs.push(SyntaxError::MissingFilter(err_locs))
     }
 
-    if let Err(e_span) = check_missing_sink(&syntax) {
+    if let Err(e_span) = check_missing_sink(syntax) {
         errs.push(SyntaxError::MissingSink(vec![e_span]));
     }
 
@@ -27,7 +25,7 @@ pub fn check(
     }
 }
 
-fn check_missing_streamer(syntax: &Vec<PipelineElement>) -> Result<(), logos::Span> {
+fn check_missing_streamer(syntax: &[PipelineElement]) -> Result<(), logos::Span> {
     if let Some(&PipelineElement {
         kind: PipelineElementKind::Pipe,
         ref span,
@@ -39,15 +37,7 @@ fn check_missing_streamer(syntax: &Vec<PipelineElement>) -> Result<(), logos::Sp
     }
 }
 
-#[test]
-fn test_check_missing_streamer() {
-    let test_data = "| invert | save \"./image_processed.jpg\"";
-    let syntax = parse_syntax(test_data).unwrap();
-
-    assert_eq!(check_missing_streamer(&syntax), Err(0..1))
-}
-
-fn check_missing_filters(syntax: &Vec<PipelineElement>) -> Result<(), Vec<logos::Span>> {
+fn check_missing_filters(syntax: &[PipelineElement]) -> Result<(), Vec<logos::Span>> {
     let mut missing_filter_locs = Vec::new();
 
     for i in 0..syntax.len() {
@@ -73,15 +63,7 @@ fn check_missing_filters(syntax: &Vec<PipelineElement>) -> Result<(), Vec<logos:
     }
 }
 
-#[test]
-fn test_check_missing_filters() {
-    let test_data = "meow | | test | awa |   | nya";
-    let syntax = parse_syntax(test_data).unwrap();
-
-    assert_eq!(check_missing_filters(&syntax), Err(vec![5..8, 20..25]))
-}
-
-fn check_missing_sink(syntax: &Vec<PipelineElement>) -> Result<(), logos::Span> {
+fn check_missing_sink(syntax: &[PipelineElement]) -> Result<(), logos::Span> {
     if let Some(&PipelineElement {
         kind: PipelineElementKind::Pipe,
         ref span,
@@ -92,11 +74,3 @@ fn check_missing_sink(syntax: &Vec<PipelineElement>) -> Result<(), logos::Span>
         Ok(())
     }
 }
-
-#[test]
-fn test_check_missing_sink() {
-    let test_data = "meow | invert | ";
-    let syntax = parse_syntax(test_data).unwrap();
-
-    assert_eq!(check_missing_sink(&syntax), Err(14..15))
-}
diff --git a/src/syntax/check/test.rs b/src/syntax/check/test.rs
new file mode 100644
index 0000000..c885303
--- /dev/null
+++ b/src/syntax/check/test.rs
@@ -0,0 +1,28 @@
+use crate::syntax::{
+    check::{check_missing_filters, check_missing_sink, check_missing_streamer},
+    parse_syntax,
+};
+
+#[test]
+fn test_check_missing_streamer() {
+    let test_data = "| invert | save \"./image_processed.jpg\"";
+    let syntax = parse_syntax(test_data).unwrap();
+
+    assert_eq!(check_missing_streamer(&syntax), Err(0..1))
+}
+
+#[test]
+fn test_check_missing_filters() {
+    let test_data = "meow | | test | awa |   | nya";
+    let syntax = parse_syntax(test_data).unwrap();
+
+    assert_eq!(check_missing_filters(&syntax), Err(vec![5..8, 20..25]))
+}
+
+#[test]
+fn test_check_missing_sink() {
+    let test_data = "meow | invert | ";
+    let syntax = parse_syntax(test_data).unwrap();
+
+    assert_eq!(check_missing_sink(&syntax), Err(14..15))
+}
diff --git a/src/syntax/error.rs b/src/syntax/error.rs
index cf5a02e..e4cdaff 100644
--- a/src/syntax/error.rs
+++ b/src/syntax/error.rs
@@ -1,7 +1,5 @@
 use codespan_reporting::diagnostic::{Diagnostic, Label};
 
-pub type FileId = usize;
-
 /// The enum representing a syntax error, used for error reporting
 #[derive(Debug, Clone)]
 pub enum SyntaxError {
@@ -27,7 +25,7 @@ impl SyntaxError {
             Self::InvalidToken(errs) => Diagnostic::error()
                 .with_message("failed to parse invalid tokens")
                 .with_labels(
-                    errs.into_iter()
+                    errs.iter()
                         .map(|span| {
                             Label::primary(file_id, span.clone()).with_message("invalid token")
                         })
@@ -36,7 +34,7 @@ impl SyntaxError {
             Self::MissingStreamer(locs) => Diagnostic::error()
                 .with_message("pipelines must always start with a streamer")
                 .with_labels(
-                    locs.into_iter()
+                    locs.iter()
                         .map(|span| {
                             Label::primary(file_id, span.clone()).with_message("missing streamer")
                         })
@@ -45,7 +43,7 @@ impl SyntaxError {
             Self::MissingFilter(locs) => Diagnostic::error()
                 .with_message("missing filters in pipelines")
                 .with_labels(
-                    locs.into_iter()
+                    locs.iter()
                         .map(|span| {
                             Label::primary(file_id, span.clone()).with_message("no filter here")
                         })
@@ -54,7 +52,7 @@ impl SyntaxError {
             Self::MissingSink(locs) => Diagnostic::error()
                 .with_message("pipelines cannot end on a pipe")
                 .with_labels(
-                    locs.into_iter()
+                    locs.iter()
                         .map(|span| Label::primary(file_id, span.clone()).with_message("no sink"))
                         .collect(),
                 ),