diff --git a/tests/build_process.rs b/tests/build_process.rs
index 10d0b4a9..c59db328 100644
--- a/tests/build_process.rs
+++ b/tests/build_process.rs
@@ -1,10 +1,8 @@
 mod dummy_book;
 
 use crate::dummy_book::DummyBook;
-use mdbook::book::Book;
 use mdbook::config::Config;
 use mdbook::errors::*;
-use mdbook::preprocess::{Preprocessor, PreprocessorContext};
 use mdbook::renderer::{RenderContext, Renderer};
 use mdbook::MDBook;
 use std::sync::{Arc, Mutex};
@@ -14,20 +12,6 @@ struct Spy(Arc<Mutex<Inner>>);
 #[derive(Debug, Default)]
 struct Inner {
     run_count: usize,
-    rendered_with: Vec<String>,
-}
-
-impl Preprocessor for Spy {
-    fn name(&self) -> &str {
-        "dummy"
-    }
-
-    fn run(&self, ctx: &PreprocessorContext, book: Book) -> Result<Book> {
-        let mut inner = self.0.lock().unwrap();
-        inner.run_count += 1;
-        inner.rendered_with.push(ctx.renderer.clone());
-        Ok(book)
-    }
 }
 
 impl Renderer for Spy {
@@ -42,26 +26,6 @@ impl Renderer for Spy {
     }
 }
 
-#[test]
-fn mdbook_runs_preprocessors() {
-    let spy: Arc<Mutex<Inner>> = Default::default();
-
-    let temp = DummyBook::new().build().unwrap();
-    let cfg = Config::default();
-
-    let mut book = MDBook::load_with_config(temp.path(), cfg).unwrap();
-    book.with_preprocessor(Spy(Arc::clone(&spy)));
-    book.build().unwrap();
-
-    let inner = spy.lock().unwrap();
-    assert_eq!(inner.run_count, 1);
-    assert_eq!(inner.rendered_with.len(), 1);
-    assert_eq!(
-        "html", inner.rendered_with[0],
-        "We should have been run with the default HTML renderer"
-    );
-}
-
 #[test]
 fn mdbook_runs_renderers() {
     let spy: Arc<Mutex<Inner>> = Default::default();
diff --git a/tests/testsuite/main.rs b/tests/testsuite/main.rs
index 5b2d7db1..daec2814 100644
--- a/tests/testsuite/main.rs
+++ b/tests/testsuite/main.rs
@@ -10,6 +10,7 @@ mod index;
 mod init;
 mod markdown;
 mod playground;
+mod preprocessor;
 
 mod prelude {
     pub use crate::book_test::BookTest;
diff --git a/tests/testsuite/preprocessor.rs b/tests/testsuite/preprocessor.rs
new file mode 100644
index 00000000..8c8793a6
--- /dev/null
+++ b/tests/testsuite/preprocessor.rs
@@ -0,0 +1,42 @@
+//! Tests for custom preprocessors.
+
+use crate::prelude::*;
+use mdbook::book::Book;
+use mdbook::errors::Result;
+use mdbook::preprocess::{Preprocessor, PreprocessorContext};
+use std::sync::{Arc, Mutex};
+
+struct Spy(Arc<Mutex<Inner>>);
+
+#[derive(Debug, Default)]
+struct Inner {
+    run_count: usize,
+    rendered_with: Vec<String>,
+}
+
+impl Preprocessor for Spy {
+    fn name(&self) -> &str {
+        "dummy"
+    }
+
+    fn run(&self, ctx: &PreprocessorContext, book: Book) -> Result<Book> {
+        let mut inner = self.0.lock().unwrap();
+        inner.run_count += 1;
+        inner.rendered_with.push(ctx.renderer.clone());
+        Ok(book)
+    }
+}
+
+// Test that preprocessor gets run.
+#[test]
+fn runs_preprocessors() {
+    let test = BookTest::init(|_| {});
+    let spy: Arc<Mutex<Inner>> = Default::default();
+    let mut book = test.load_book();
+    book.with_preprocessor(Spy(Arc::clone(&spy)));
+    book.build().unwrap();
+
+    let inner = spy.lock().unwrap();
+    assert_eq!(inner.run_count, 1);
+    assert_eq!(inner.rendered_with, ["html"]);
+}