Migrate ask_the_preprocessor_to_blow_up to BookTest

tests/custom_preprocessors.rs

@@ -28,31 +28,3 @@ fn example_doesnt_support_not_supported() {
 
     assert_eq!(got, false);
 }
-
-#[test]
-fn ask_the_preprocessor_to_blow_up() {
-    let dummy_book = DummyBook::new();
-    let temp = dummy_book.build().unwrap();
-    let mut md = MDBook::load(temp.path()).unwrap();
-    md.with_preprocessor(example());
-
-    md.config
-        .set("preprocessor.nop-preprocessor.blow-up", true)
-        .unwrap();
-
-    let got = md.build();
-
-    assert!(got.is_err());
-    let error_message = got.err().unwrap().to_string();
-    let status = if cfg!(windows) {
-        "exit code: 1"
-    } else {
-        "exit status: 1"
-    };
-    assert_eq!(
-        error_message,
-        format!(
-            r#"The "nop-preprocessor" preprocessor exited unsuccessfully with {status} status"#
-        )
-    );
-}

tests/testsuite/preprocessor.rs

@@ -52,3 +52,19 @@ fn nop_preprocessor() {
 "#]]);
     });
 }
+
+// Failing preprocessor generates an error.
+#[test]
+fn failing_preprocessor() {
+    BookTest::from_dir("preprocessor/failing_preprocessor")
+        .run("build", |cmd| {
+            cmd.expect_failure()
+                .expect_stdout(str![[""]])
+                .expect_stderr(str![[r#"
+[TIMESTAMP] [INFO] (mdbook::book): Book building has started
+Boom!!1!
+[TIMESTAMP] [ERROR] (mdbook::utils): Error: The "nop-preprocessor" preprocessor exited unsuccessfully with [EXIT_STATUS]: 1 status
+
+"#]]);
+        });
+}

tests/testsuite/preprocessor/failing_preprocessor/book.toml

@@ -0,0 +1,4 @@
+[preprocessor.nop-preprocessor]
+command = "cargo run --quiet --example nop-preprocessor --"
+blow-up = true
+