doc tests depends on feature

Index: imara-diff/src/lib.rs
===================================================================
--- imara-diff.orig/src/lib.rs
+++ imara-diff/src/lib.rs
@@ -30,14 +30,17 @@
 //!
 //! ```
 //! use imara_diff::intern::InternedInput;
+//! #[cfg(feature = "unified_diff")]
 //! use imara_diff::{diff, Algorithm, UnifiedDiffBuilder};
 //!
+//! #[cfg(feature = "unified_diff")]
 //! let before = r#"fn foo() -> Bar {
 //!     let mut foo = 2;
 //!     foo *= 50;
 //!     println!("hello world")
 //! }"#;
 //!
+//! #[cfg(feature = "unified_diff")]
 //! let after = r#"// lorem ipsum
 //! fn foo() -> Bar {
 //!     let mut foo = 2;
@@ -48,8 +51,11 @@
 //! // foo
 //! "#;
 //!
+//! #[cfg(feature = "unified_diff")]
 //! let input = InternedInput::new(before, after);
+//! #[cfg(feature = "unified_diff")]
 //! let diff = diff(Algorithm::Histogram, &input, UnifiedDiffBuilder::new(&input));
+//! #[cfg(feature = "unified_diff")]
 //! assert_eq!(
 //!     diff,
 //!     r#"@@ -1,5 +1,8 @@
@@ -73,14 +79,17 @@
 //! use std::ops::Range;
 //!
 //! use imara_diff::intern::InternedInput;
+//! #[cfg(feature = "unified_diff")]
 //! use imara_diff::{diff, Algorithm, UnifiedDiffBuilder};
 //!
+//! #[cfg(feature = "unified_diff")]
 //! let before = r#"fn foo() -> Bar {
 //!     let mut foo = 2;
 //!     foo *= 50;
 //!     println!("hello world")
 //! }"#;
 //!
+//! #[cfg(feature = "unified_diff")]
 //! let after = r#"// lorem ipsum
 //! fn foo() -> Bar {
 //!     let mut foo = 2;
@@ -91,11 +100,16 @@
 //! // foo
 //! "#;
 //!
+//! #[cfg(feature = "unified_diff")]
 //! let mut insertions = Vec::new();
+//! #[cfg(feature = "unified_diff")]
 //! let mut removals = Vec::new();
+//! #[cfg(feature = "unified_diff")]
 //! let mut replacements = Vec::new();
 //!
+//! #[cfg(feature = "unified_diff")]
 //! let input = InternedInput::new(before, after);
+//! #[cfg(feature = "unified_diff")]
 //! let sink = |before: Range<u32>, after: Range<u32>| {
 //!     let hunk_before: Vec<_> = input.before[before.start as usize..before.end as usize]
 //!         .iter()
@@ -113,9 +127,13 @@
 //!         replacements.push((hunk_before, hunk_after))
 //!     }
 //! };
+//! #[cfg(feature = "unified_diff")]
 //! let diff = diff(Algorithm::Histogram, &input, sink);
+//! #[cfg(feature = "unified_diff")]
 //! assert_eq!(&insertions, &[vec!["// lorem ipsum"], vec!["// foo"]]);
+//! #[cfg(feature = "unified_diff")]
 //! assert!(removals.is_empty());
+//! #[cfg(feature = "unified_diff")]
 //! assert_eq!(
 //!     &replacements,
 //!     &[(
@@ -133,19 +151,30 @@
 //! use imara_diff::intern::InternedInput;
 //! use imara_diff::sink::Counter;
 //! use imara_diff::sources::lines_with_terminator;
+//! #[cfg(feature = "unified_diff")]
 //! use imara_diff::{diff, Algorithm, UnifiedDiffBuilder};
 //!
+//! #[cfg(feature = "unified_diff")]
 //! let before = "foo";
+//! #[cfg(feature = "unified_diff")]
 //! let after = "foo\n";
 //!
+//! #[cfg(feature = "unified_diff")]
 //! let input = InternedInput::new(before, after);
+//! #[cfg(feature = "unified_diff")]
 //! let changes = diff(Algorithm::Histogram, &input, Counter::default());
+//! #[cfg(feature = "unified_diff")]
 //! assert_eq!(changes.insertions, 0);
+//! #[cfg(feature = "unified_diff")]
 //! assert_eq!(changes.removals, 0);
 //!
+//! #[cfg(feature = "unified_diff")]
 //! let input = InternedInput::new(lines_with_terminator(before), lines_with_terminator(after));
+//! #[cfg(feature = "unified_diff")]
 //! let changes = diff(Algorithm::Histogram, &input, Counter::default());
+//! #[cfg(feature = "unified_diff")]
 //! assert_eq!(changes.insertions, 1);
+//! #[cfg(feature = "unified_diff")]
 //! assert_eq!(changes.removals, 1);
 //! ```
 
Index: imara-diff/src/tests.rs
===================================================================
--- imara-diff.orig/src/tests.rs
+++ imara-diff/src/tests.rs
@@ -6,8 +6,11 @@ use expect_test::{expect, expect_file};
 
 use crate::intern::InternedInput;
 use crate::sink::Counter;
-use crate::{diff, Algorithm, UnifiedDiffBuilder};
+use crate::{diff, Algorithm};
+#[cfg(feature = "unified_diff")]
+use crate::UnifiedDiffBuilder;
 
+#[cfg(feature = "unified_diff")]
 #[test]
 fn replace() {
     let before = r#"fn foo() -> Bar{
@@ -45,6 +48,7 @@ fn foo() -> Bar{
     }
 }
 
+#[cfg(feature = "unified_diff")]
 #[test]
 fn identical_files() {
     let file = r#"fn foo() -> Bar{
@@ -60,6 +64,7 @@ fn identical_files() {
     }
 }
 
+#[cfg(feature = "unified_diff")]
 #[test]
 fn simple_insert() {
     let before = r#"fn foo() -> Bar{
@@ -116,6 +121,7 @@ pub fn project_root() -> PathBuf {
     res
 }
 
+#[cfg(feature = "unified_diff")]
 //#[test]
 #[cfg(not(miri))]
 fn hand_checked_udiffs() {