diff --git a/tests/custom_preprocessors.rs b/tests/custom_preprocessors.rs
deleted file mode 100644
index 6baa5db9..00000000
--- a/tests/custom_preprocessors.rs
+++ /dev/null
@@ -1,30 +0,0 @@
-mod dummy_book;
-
-use crate::dummy_book::DummyBook;
-use mdbook::preprocess::{CmdPreprocessor, Preprocessor};
-use mdbook::MDBook;
-
-fn example() -> CmdPreprocessor {
-    CmdPreprocessor::new(
-        "nop-preprocessor".to_string(),
-        "cargo run --example nop-preprocessor --".to_string(),
-    )
-}
-
-#[test]
-fn example_supports_whatever() {
-    let cmd = example();
-
-    let got = cmd.supports_renderer("whatever");
-
-    assert_eq!(got, true);
-}
-
-#[test]
-fn example_doesnt_support_not_supported() {
-    let cmd = example();
-
-    let got = cmd.supports_renderer("not-supported");
-
-    assert_eq!(got, false);
-}
diff --git a/tests/testsuite/preprocessor.rs b/tests/testsuite/preprocessor.rs
index 4c620c3a..d2c1608b 100644
--- a/tests/testsuite/preprocessor.rs
+++ b/tests/testsuite/preprocessor.rs
@@ -3,7 +3,7 @@
 use crate::prelude::*;
 use mdbook::book::Book;
 use mdbook::errors::Result;
-use mdbook::preprocess::{Preprocessor, PreprocessorContext};
+use mdbook::preprocess::{CmdPreprocessor, Preprocessor, PreprocessorContext};
 use std::sync::{Arc, Mutex};
 
 struct Spy(Arc<Mutex<Inner>>);
@@ -68,3 +68,28 @@ Boom!!1!
 "#]]);
         });
 }
+
+fn example() -> CmdPreprocessor {
+    CmdPreprocessor::new(
+        "nop-preprocessor".to_string(),
+        "cargo run --quiet --example nop-preprocessor --".to_string(),
+    )
+}
+
+#[test]
+fn example_supports_whatever() {
+    let cmd = example();
+
+    let got = cmd.supports_renderer("whatever");
+
+    assert_eq!(got, true);
+}
+
+#[test]
+fn example_doesnt_support_not_supported() {
+    let cmd = example();
+
+    let got = cmd.supports_renderer("not-supported");
+
+    assert_eq!(got, false);
+}