Move `Suggestion` to a new module

Planning to separate the `Suggestion` and `Client` code.

2 files changed, 459 insertions, 444 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 31df669..4a15852 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,18 +1,15 @@
 #![warn(rust_2018_idioms)]
 
 
+pub mod suggestion;
+
 mod url;
 
+pub use crate::suggestion::Suggestion;
 pub use crate::url::SuggestionUrl;
 
 
-use std::io::{BufRead, BufReader, BufWriter, Write};
-use std::path::Path;
-
-use git2::{Patch, Repository};
 use github_rs::client::{Executor, Github};
-use regex::Regex;
-use serde::Deserialize;
 use serde_json::Value;
 use thiserror::Error;
 
@@ -63,182 +60,6 @@ impl<'a> Client<'a> {
     }
 }
 
-#[derive(Debug, PartialEq)]
-enum LineEnding {
-    Lf,
-    CrLf,
-}
-
-#[derive(Debug, Deserialize)]
-pub struct Suggestion {
-    #[serde(rename = "diff_hunk")]
-    diff: String,
-
-    #[serde(rename = "body")]
-    comment: String,
-
-    #[serde(rename = "original_commit_id")]
-    commit: String,
-
-    path: String,
-
-    original_start_line: Option<usize>,
-
-    #[serde(rename = "original_line")]
-    original_end_line: usize,
-}
-
-impl Suggestion {
-    // TODO: Rename to `diff`
-    pub fn patch(&self) -> String {
-        let mut diff: Vec<_> = self.diff.lines()
-            .filter(|l| !l.starts_with("-"))
-            .map(|l| {
-                if l.starts_with("+") {
-                    return l.replacen("+", " ", 1);
-                }
-
-                l.to_owned()
-            })
-            .collect();
-
-        let last = diff.len() - 1;
-        diff[last] = diff.last().unwrap()
-            .replacen(" ", "-", 1);
-
-        diff.push(self.suggestion_patch());
-
-        diff.join("\n")
-    }
-
-    pub fn diff(&self) -> String {
-        let repo = Repository::open(".").unwrap();
-
-        self.diff_with_repo(&repo)
-    }
-
-    fn diff_with_repo(&self, repo: &Repository) -> String {
-        let commit = repo.find_commit(self.commit.parse().unwrap()).unwrap();
-
-        let path = Path::new(&self.path);
-
-        let object = commit
-            .tree().unwrap()
-            .get_path(path).unwrap()
-            .to_object(&repo).unwrap();
-
-        let blob = object.as_blob().unwrap();
-
-        let blob_reader = BufReader::new(blob.content());
-        let mut new = BufWriter::new(Vec::new());
-        self.apply_to(blob_reader, &mut new).unwrap();
-        let new_buffer = new.into_inner().unwrap();
-
-        let mut diff = Patch::from_blob_and_buffer(
-            blob,
-            Some(&path),
-            &new_buffer,
-            Some(&path),
-            None,
-        ).unwrap();
-
-        diff.to_buf()
-            .unwrap()
-            .as_str()
-            .unwrap_or("")
-            .to_owned()
-    }
-
-    fn suggestion_patch(&self) -> String {
-        let re = Regex::new(r"(?s).*(?-s)```\s*suggestion.*\n").unwrap();
-        let s = re.replace(&self.comment, "+");
-        s.replace("```", "")
-    }
-
-    fn suggestion(&self) -> String {
-        self.suggestion_with_line_ending(&LineEnding::Lf)
-    }
-
-    fn suggestion_with_line_ending(&self, line_ending: &LineEnding) -> String {
-        let re = Regex::new(r"(?s).*(?-s)```\s*suggestion.*\n").unwrap();
-        let s = re.replace(&self.comment, "");
-        let s = s.replace("```", "");
-
-        // Suggestion blocks use CRLF by default.
-        if *line_ending == LineEnding::Lf {
-            return s.replace('\r', "");
-        }
-
-        s
-    }
-
-    pub fn apply(&self) -> Result<(), Error> {
-        let repo = Repository::open(".").unwrap();
-
-        let diff_text = self.diff_with_repo(&repo);
-        let diff = git2::Diff::from_buffer(diff_text.as_bytes()).unwrap();
-
-        repo.apply(
-            &diff,
-            git2::ApplyLocation::WorkDir,
-            None,
-        ).unwrap();
-
-        Ok(())
-    }
-
-    fn apply_to<R: BufRead, W: Write>(
-        &self,
-        reader: R,
-        writer: &mut W,
-    ) -> Result<(), Error> {
-        let mut line_ending = LineEnding::Lf;
-
-        for (i, line) in reader.lines().enumerate() {
-            let line_number = i + 1;
-
-            match line {
-                Ok(l) => {
-                    // Determine which line endings the file uses by looking at
-                    // the first line.
-                    if line_number == 1 && is_line_crlf(&l) {
-                        line_ending = LineEnding::CrLf;
-                    }
-
-                    if line_number == self.original_end_line {
-                        write!(
-                            writer,
-                            "{}",
-                            self.suggestion_with_line_ending(&line_ending),
-                        ).unwrap();
-                    } else if self.original_start_line.is_none()
-                            || line_number < self.original_start_line.unwrap()
-                            || line_number > self.original_end_line {
-                        writeln!(writer, "{}", l).unwrap();
-                    }
-                },
-                Err(e) => panic!(e),
-            }
-        }
-
-        Ok(())
-    }
-}
-
-/// Determine the line ending for `line`.
-///
-/// If the second-to-last character on the first line is "\r", assume CRLF.
-/// Otherwise, default to LF.
-fn is_line_crlf(line: &str) -> bool {
-    if let Some(c) = line.chars().rev().nth(2) {
-        if c == '\r' {
-            return true;
-        }
-    }
-
-    false
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -256,266 +77,4 @@ mod tests {
 
         println!("{:?}", suggestion);
     }
-
-    #[test]
-    fn suggestion_patch_generates_patch() {
-        // Diff from gabgodBB (https://github.com/gabgodBB) and suggestion from
-        // probablycorey (https://github.com/probablycorey) in this pull
-        // request: https://github.com/cli/cli/pull/1123
-
-        let suggestion = Suggestion {
-            diff: r#"@@ -1, 9 +1, 11 @@
- package command
- 
- import (
-+	"bufio" // used to input comment
- 	"errors"
- 	"fmt"
- 	"io"
-+	"os" // used to input comment"#.to_owned(),
-            comment: r#"It's ok to leave these uncommented
-
-```suggestion
-	"os"
-```"#.to_owned(),
-            commit: "".to_owned(),
-            path: "".to_owned(),
-            original_start_line: Some(8),
-            original_end_line: 8,
-        };
-
-        assert_eq!(
-            suggestion.patch(),
-            r#"@@ -1, 9 +1, 11 @@
- package command
- 
- import (
- 	"bufio" // used to input comment
- 	"errors"
- 	"fmt"
- 	"io"
--	"os" // used to input comment
-+	"os"
-"#,
-        );
-    }
-
-    #[test]
-    fn unified_diff() {
-        use unidiff::PatchSet;
-
-        let diff = r#"--- a/command/pr.go
-+++ b/command/pr.go
-@@ -1,9 +1,11 @@
- package command
- 
- import (
-+	"bufio" // used to input comment
- 	"errors"
- 	"fmt"
- 	"io"
-+	"os" // used to input comment
-"#;
-
-        let mut patch = PatchSet::new();
-        patch.parse(diff).unwrap();
-
-        println!("{:?}", patch);
-        println!("{}", patch);
-
-        let lines = patch.files_mut()[0].hunks_mut()[0].lines_mut();
-
-        // for line in &lines {
-        //     if line.is_removed() {
-        //     } else if line.is_added() {
-        //         line.line_type = unidiff::LINE_TYPE_CONTEXT.to_owned();
-        //     }
-        // }
-
-        lines
-            .iter_mut()
-            .filter(|l| !l.is_removed())
-            // .map(|l| {
-            .for_each(|l| {
-                if l.is_added() {
-                    l.line_type = unidiff::LINE_TYPE_CONTEXT.to_owned();
-                }
-            });
-
-        lines[lines.len() - 2].line_type = unidiff::LINE_TYPE_REMOVED.to_owned();
-
-        patch.files_mut()[0].hunks_mut()[0].append(unidiff::Line::new(
-            r#"	"os""#,
-            unidiff::LINE_TYPE_ADDED,
-        ));
-
-        println!("{}", patch);
-    }
-
-    #[test]
-    fn read_git_blob() {
-        use std::path::Path;
-
-        use git2::Repository;
-
-        let repo = Repository::open("./private/suggestion-test").unwrap();
-        let commit = repo.find_commit("b58be52880a0a0c0d397052351be31f19acdeca4".parse().unwrap()).unwrap();
-
-        let object = commit
-            .tree().unwrap()
-            .get_path(Path::new("src/server.rs")).unwrap()
-            .to_object(&repo).unwrap();
-
-        let blob = object
-            .as_blob().unwrap()
-            .content();
-
-        println!("{:?}", commit);
-        println!("{}", std::str::from_utf8(blob).unwrap());
-    }
-
-    #[test]
-    fn suggestion_diff_with_repo_generates_diff() {
-        use tempfile::tempdir;
-
-
-        let git_root = tempdir().unwrap();
-        let repo = Repository::init(git_root.path()).unwrap();
-
-        let file = r#"
-     ‘Beware the Jabberwock, my son!
-      The jaws that bite, the claws that catch!
-     Beware the Jubjub bird, and shun
-      The frumious Bandersnatch!’
-
-     He took his vorpal blade in hand:
-      Long time the manxome foe he sought--
-     So rested he by the Tumtum tree,
-      And stood awhile in thought.
-"#;
-
-        let path = "poems/Jabberwocky.txt";
-
-        let mut index = repo.index().unwrap();
-        index.add_frombuffer(
-            &git2::IndexEntry {
-                ctime: git2::IndexTime::new(0, 0),
-                mtime: git2::IndexTime::new(0, 0),
-                dev: 0,
-                ino: 0,
-                mode: 0o100644,
-                uid: 0,
-                gid: 0,
-                file_size: file.len() as u32,
-                id: git2::Oid::zero(),
-                flags: 0,
-                flags_extended: 0,
-                path: path.as_bytes().to_vec(),
-            },
-            file.as_bytes(),
-        ).unwrap();
-        let tree_oid = index.write_tree().unwrap();
-        let tree = repo.find_tree(tree_oid).unwrap();
-
-        let author = git2::Signature::now(
-            "Oshino Shinobu",
-            "oshino.shinobu@example.com",
-        ).unwrap();
-
-        let commit = repo.commit(
-            Some("HEAD"),
-            &author,
-            &author,
-            "Sample commit",
-            &tree,
-            &[],
-        ).unwrap();
-
-        let suggestion = Suggestion {
-            diff: "".to_owned(),
-            comment: r#"``` suggestion
-     He took his vorpal sword in hand:
-      Long time the manxome foe he sought—
-```"#.to_owned(),
-            commit: commit.to_string(),
-            path: path.to_owned(),
-            original_start_line: Some(7),
-            original_end_line: 8,
-        };
-
-        let expected = r#"diff --git a/poems/Jabberwocky.txt b/poems/Jabberwocky.txt
-index 89840a2..06acdfc 100644
---- a/poems/Jabberwocky.txt
-+++ b/poems/Jabberwocky.txt
-@@ -4,7 +4,7 @@
-      Beware the Jubjub bird, and shun
-       The frumious Bandersnatch!’
- 
--     He took his vorpal blade in hand:
--      Long time the manxome foe he sought--
-+     He took his vorpal sword in hand:
-+      Long time the manxome foe he sought—
-      So rested he by the Tumtum tree,
-       And stood awhile in thought.
-"#;
-
-        assert_eq!(
-            suggestion.diff_with_repo(&repo),
-            expected,
-        );
-    }
-
-    #[test]
-    fn suggestion_apply_to_writes_patch_to_writer() {
-        use std::io::Cursor;
-
-
-        let mut original_buffer = Vec::new();
-        let original = r#"
-     ‘Beware the Jabberwock, my son!
-      The jaws that bite, the claws that catch!
-     Beware the Jubjub bird, and shun
-      The frumious Bandersnatch!’
-
-     He took his vorpal blade in hand:
-      Long time the manxome foe he sought--
-     So rested he by the Tumtum tree,
-      And stood awhile in thought.
-"#;
-
-        write!(original_buffer, "{}", original).unwrap();
-
-        let suggestion = Suggestion {
-            diff: "".to_owned(),
-            comment: r#"``` suggestion
-     He took his vorpal sword in hand:
-      Long time the manxome foe he sought—
-```"#.to_owned(),
-            commit: "".to_owned(),
-            path: "".to_owned(),
-            original_start_line: Some(7),
-            original_end_line: 8,
-        };
-
-        let expected = r#"
-     ‘Beware the Jabberwock, my son!
-      The jaws that bite, the claws that catch!
-     Beware the Jubjub bird, and shun
-      The frumious Bandersnatch!’
-
-     He took his vorpal sword in hand:
-      Long time the manxome foe he sought—
-     So rested he by the Tumtum tree,
-      And stood awhile in thought.
-"#;
-
-        let original_reader = Cursor::new(original_buffer);
-        let mut actual = Cursor::new(Vec::new());
-        suggestion.apply_to(original_reader, &mut actual).unwrap();
-
-        assert_eq!(
-            std::str::from_utf8(&actual.into_inner()).unwrap(),
-            expected,
-        );
-    }
 }
diff --git a/src/suggestion.rs b/src/suggestion.rs
new file mode 100644
index 0000000..68a2430
--- /dev/null
+++ b/src/suggestion.rs
@@ -0,0 +1,456 @@
+use std::io::{BufRead, BufReader, BufWriter, Write};
+use std::path::Path;
+
+use git2::{Patch, Repository};
+use regex::Regex;
+use serde::Deserialize;
+use thiserror::Error;
+
+
+#[derive(Debug, Error)]
+pub enum Error {
+}
+
+#[derive(Debug, PartialEq)]
+enum LineEnding {
+    Lf,
+    CrLf,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct Suggestion {
+    #[serde(rename = "diff_hunk")]
+    diff: String,
+
+    #[serde(rename = "body")]
+    comment: String,
+
+    #[serde(rename = "original_commit_id")]
+    commit: String,
+
+    path: String,
+
+    original_start_line: Option<usize>,
+
+    #[serde(rename = "original_line")]
+    original_end_line: usize,
+}
+
+impl Suggestion {
+    // TODO: Rename to `diff`
+    pub fn patch(&self) -> String {
+        let mut diff: Vec<_> = self.diff.lines()
+            .filter(|l| !l.starts_with("-"))
+            .map(|l| {
+                if l.starts_with("+") {
+                    return l.replacen("+", " ", 1);
+                }
+
+                l.to_owned()
+            })
+            .collect();
+
+        let last = diff.len() - 1;
+        diff[last] = diff.last().unwrap()
+            .replacen(" ", "-", 1);
+
+        diff.push(self.suggestion_patch());
+
+        diff.join("\n")
+    }
+
+    pub fn diff(&self) -> String {
+        let repo = Repository::open(".").unwrap();
+
+        self.diff_with_repo(&repo)
+    }
+
+    fn diff_with_repo(&self, repo: &Repository) -> String {
+        let commit = repo.find_commit(self.commit.parse().unwrap()).unwrap();
+
+        let path = Path::new(&self.path);
+
+        let object = commit
+            .tree().unwrap()
+            .get_path(path).unwrap()
+            .to_object(&repo).unwrap();
+
+        let blob = object.as_blob().unwrap();
+
+        let blob_reader = BufReader::new(blob.content());
+        let mut new = BufWriter::new(Vec::new());
+        self.apply_to(blob_reader, &mut new).unwrap();
+        let new_buffer = new.into_inner().unwrap();
+
+        let mut diff = Patch::from_blob_and_buffer(
+            blob,
+            Some(&path),
+            &new_buffer,
+            Some(&path),
+            None,
+        ).unwrap();
+
+        diff.to_buf()
+            .unwrap()
+            .as_str()
+            .unwrap_or("")
+            .to_owned()
+    }
+
+    fn suggestion_patch(&self) -> String {
+        let re = Regex::new(r"(?s).*(?-s)```\s*suggestion.*\n").unwrap();
+        let s = re.replace(&self.comment, "+");
+        s.replace("```", "")
+    }
+
+    fn suggestion(&self) -> String {
+        self.suggestion_with_line_ending(&LineEnding::Lf)
+    }
+
+    fn suggestion_with_line_ending(&self, line_ending: &LineEnding) -> String {
+        let re = Regex::new(r"(?s).*(?-s)```\s*suggestion.*\n").unwrap();
+        let s = re.replace(&self.comment, "");
+        let s = s.replace("```", "");
+
+        // Suggestion blocks use CRLF by default.
+        if *line_ending == LineEnding::Lf {
+            return s.replace('\r', "");
+        }
+
+        s
+    }
+
+    pub fn apply(&self) -> Result<(), Error> {
+        let repo = Repository::open(".").unwrap();
+
+        let diff_text = self.diff_with_repo(&repo);
+        let diff = git2::Diff::from_buffer(diff_text.as_bytes()).unwrap();
+
+        repo.apply(
+            &diff,
+            git2::ApplyLocation::WorkDir,
+            None,
+        ).unwrap();
+
+        Ok(())
+    }
+
+    fn apply_to<R: BufRead, W: Write>(
+        &self,
+        reader: R,
+        writer: &mut W,
+    ) -> Result<(), Error> {
+        let mut line_ending = LineEnding::Lf;
+
+        for (i, line) in reader.lines().enumerate() {
+            let line_number = i + 1;
+
+            match line {
+                Ok(l) => {
+                    // Determine which line endings the file uses by looking at
+                    // the first line.
+                    if line_number == 1 && is_line_crlf(&l) {
+                        line_ending = LineEnding::CrLf;
+                    }
+
+                    if line_number == self.original_end_line {
+                        write!(
+                            writer,
+                            "{}",
+                            self.suggestion_with_line_ending(&line_ending),
+                        ).unwrap();
+                    } else if self.original_start_line.is_none()
+                            || line_number < self.original_start_line.unwrap()
+                            || line_number > self.original_end_line {
+                        writeln!(writer, "{}", l).unwrap();
+                    }
+                },
+                Err(e) => panic!(e),
+            }
+        }
+
+        Ok(())
+    }
+}
+
+/// Determine the line ending for `line`.
+///
+/// If the second-to-last character on the first line is "\r", assume CRLF.
+/// Otherwise, default to LF.
+fn is_line_crlf(line: &str) -> bool {
+    if let Some(c) = line.chars().rev().nth(2) {
+        if c == '\r' {
+            return true;
+        }
+    }
+
+    false
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn suggestion_patch_generates_patch() {
+        // Diff from gabgodBB (https://github.com/gabgodBB) and suggestion from
+        // probablycorey (https://github.com/probablycorey) in this pull
+        // request: https://github.com/cli/cli/pull/1123
+
+        let suggestion = Suggestion {
+            diff: r#"@@ -1, 9 +1, 11 @@
+ package command
+ 
+ import (
++	"bufio" // used to input comment
+ 	"errors"
+ 	"fmt"
+ 	"io"
++	"os" // used to input comment"#.to_owned(),
+            comment: r#"It's ok to leave these uncommented
+
+```suggestion
+	"os"
+```"#.to_owned(),
+            commit: "".to_owned(),
+            path: "".to_owned(),
+            original_start_line: Some(8),
+            original_end_line: 8,
+        };
+
+        assert_eq!(
+            suggestion.patch(),
+            r#"@@ -1, 9 +1, 11 @@
+ package command
+ 
+ import (
+ 	"bufio" // used to input comment
+ 	"errors"
+ 	"fmt"
+ 	"io"
+-	"os" // used to input comment
++	"os"
+"#,
+        );
+    }
+
+    #[test]
+    fn unified_diff() {
+        use unidiff::PatchSet;
+
+        let diff = r#"--- a/command/pr.go
++++ b/command/pr.go
+@@ -1,9 +1,11 @@
+ package command
+ 
+ import (
++	"bufio" // used to input comment
+ 	"errors"
+ 	"fmt"
+ 	"io"
++	"os" // used to input comment
+"#;
+
+        let mut patch = PatchSet::new();
+        patch.parse(diff).unwrap();
+
+        println!("{:?}", patch);
+        println!("{}", patch);
+
+        let lines = patch.files_mut()[0].hunks_mut()[0].lines_mut();
+
+        // for line in &lines {
+        //     if line.is_removed() {
+        //     } else if line.is_added() {
+        //         line.line_type = unidiff::LINE_TYPE_CONTEXT.to_owned();
+        //     }
+        // }
+
+        lines
+            .iter_mut()
+            .filter(|l| !l.is_removed())
+            // .map(|l| {
+            .for_each(|l| {
+                if l.is_added() {
+                    l.line_type = unidiff::LINE_TYPE_CONTEXT.to_owned();
+                }
+            });
+
+        lines[lines.len() - 2].line_type = unidiff::LINE_TYPE_REMOVED.to_owned();
+
+        patch.files_mut()[0].hunks_mut()[0].append(unidiff::Line::new(
+            r#"	"os""#,
+            unidiff::LINE_TYPE_ADDED,
+        ));
+
+        println!("{}", patch);
+    }
+
+    #[test]
+    fn read_git_blob() {
+        use std::path::Path;
+
+        use git2::Repository;
+
+        let repo = Repository::open("./private/suggestion-test").unwrap();
+        let commit = repo.find_commit("b58be52880a0a0c0d397052351be31f19acdeca4".parse().unwrap()).unwrap();
+
+        let object = commit
+            .tree().unwrap()
+            .get_path(Path::new("src/server.rs")).unwrap()
+            .to_object(&repo).unwrap();
+
+        let blob = object
+            .as_blob().unwrap()
+            .content();
+
+        println!("{:?}", commit);
+        println!("{}", std::str::from_utf8(blob).unwrap());
+    }
+
+    #[test]
+    fn suggestion_diff_with_repo_generates_diff() {
+        use tempfile::tempdir;
+
+
+        let git_root = tempdir().unwrap();
+        let repo = Repository::init(git_root.path()).unwrap();
+
+        let file = r#"
+     ‘Beware the Jabberwock, my son!
+      The jaws that bite, the claws that catch!
+     Beware the Jubjub bird, and shun
+      The frumious Bandersnatch!’
+
+     He took his vorpal blade in hand:
+      Long time the manxome foe he sought--
+     So rested he by the Tumtum tree,
+      And stood awhile in thought.
+"#;
+
+        let path = "poems/Jabberwocky.txt";
+
+        let mut index = repo.index().unwrap();
+        index.add_frombuffer(
+            &git2::IndexEntry {
+                ctime: git2::IndexTime::new(0, 0),
+                mtime: git2::IndexTime::new(0, 0),
+                dev: 0,
+                ino: 0,
+                mode: 0o100644,
+                uid: 0,
+                gid: 0,
+                file_size: file.len() as u32,
+                id: git2::Oid::zero(),
+                flags: 0,
+                flags_extended: 0,
+                path: path.as_bytes().to_vec(),
+            },
+            file.as_bytes(),
+        ).unwrap();
+        let tree_oid = index.write_tree().unwrap();
+        let tree = repo.find_tree(tree_oid).unwrap();
+
+        let author = git2::Signature::now(
+            "Oshino Shinobu",
+            "oshino.shinobu@example.com",
+        ).unwrap();
+
+        let commit = repo.commit(
+            Some("HEAD"),
+            &author,
+            &author,
+            "Sample commit",
+            &tree,
+            &[],
+        ).unwrap();
+
+        let suggestion = Suggestion {
+            diff: "".to_owned(),
+            comment: r#"``` suggestion
+     He took his vorpal sword in hand:
+      Long time the manxome foe he sought—
+```"#.to_owned(),
+            commit: commit.to_string(),
+            path: path.to_owned(),
+            original_start_line: Some(7),
+            original_end_line: 8,
+        };
+
+        let expected = r#"diff --git a/poems/Jabberwocky.txt b/poems/Jabberwocky.txt
+index 89840a2..06acdfc 100644
+--- a/poems/Jabberwocky.txt
++++ b/poems/Jabberwocky.txt
+@@ -4,7 +4,7 @@
+      Beware the Jubjub bird, and shun
+       The frumious Bandersnatch!’
+ 
+-     He took his vorpal blade in hand:
+-      Long time the manxome foe he sought--
++     He took his vorpal sword in hand:
++      Long time the manxome foe he sought—
+      So rested he by the Tumtum tree,
+       And stood awhile in thought.
+"#;
+
+        assert_eq!(
+            suggestion.diff_with_repo(&repo),
+            expected,
+        );
+    }
+
+    #[test]
+    fn suggestion_apply_to_writes_patch_to_writer() {
+        use std::io::Cursor;
+
+
+        let mut original_buffer = Vec::new();
+        let original = r#"
+     ‘Beware the Jabberwock, my son!
+      The jaws that bite, the claws that catch!
+     Beware the Jubjub bird, and shun
+      The frumious Bandersnatch!’
+
+     He took his vorpal blade in hand:
+      Long time the manxome foe he sought--
+     So rested he by the Tumtum tree,
+      And stood awhile in thought.
+"#;
+
+        write!(original_buffer, "{}", original).unwrap();
+
+        let suggestion = Suggestion {
+            diff: "".to_owned(),
+            comment: r#"``` suggestion
+     He took his vorpal sword in hand:
+      Long time the manxome foe he sought—
+```"#.to_owned(),
+            commit: "".to_owned(),
+            path: "".to_owned(),
+            original_start_line: Some(7),
+            original_end_line: 8,
+        };
+
+        let expected = r#"
+     ‘Beware the Jabberwock, my son!
+      The jaws that bite, the claws that catch!
+     Beware the Jubjub bird, and shun
+      The frumious Bandersnatch!’
+
+     He took his vorpal sword in hand:
+      Long time the manxome foe he sought—
+     So rested he by the Tumtum tree,
+      And stood awhile in thought.
+"#;
+
+        let original_reader = Cursor::new(original_buffer);
+        let mut actual = Cursor::new(Vec::new());
+        suggestion.apply_to(original_reader, &mut actual).unwrap();
+
+        assert_eq!(
+            std::str::from_utf8(&actual.into_inner()).unwrap(),
+            expected,
+        );
+    }
+}