Do some automated random testing of Rope

Replace `rope.rs` with `rope/mod.rs` and `rope/tests/mod.rs` in
preparation for adding more elaborate testing for `Rope`.

Cargo.toml

@@ -1,7 +1,3 @@
-[package]
-name = "ged"
-version = "0.1.0"
-edition = "2021"
-
-[dev-dependencies]
-ntest = "0.9.3"
+[workspace]
+resolver = "2"
+members = ["core"]

core/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "ged-core"
+version = "0.1.0"
+edition = "2021"
+
+[dev-dependencies]
+ntest = "0.9.3"
+rand = {version="0.8.5", features=["small_rng"]}

core/src/rope/mod.rs

@@ -1,4 +1,5 @@
-use {super::fibbonacci::fibbonacci, std::rc::Rc};
+use super::fibbonacci::fibbonacci;
+pub use std::rc::Rc;
 
 /// [Rope](https://en.wikipedia.org/wiki/Rope_(data_structure)) data structure
 /// implementation.
@@ -213,6 +214,12 @@ impl Rope {
         CharIterator::new(self)
     }
 
+    /// Returns an iterator over the chars of the text which also contains the
+    /// current line and column.
+    pub fn iter_chars_with_point(self: &Rc<Self>) -> CharWithPointIterator {
+        CharWithPointIterator::new(self)
+    }
+
     /// Concatenate two Ropes without rebalancing.
     ///
     /// Combines to ropes by creating a new parent node and adding `left` and
@@ -283,20 +290,44 @@ impl Iterator for NodeIterator {
     }
 }
 
-pub struct CharIterator {
-    node_iterator: NodeIterator,
-    current_text: Option<String>,
-    str_index: usize,
-}
+pub struct CharIterator(CharWithPointIterator);
 
 impl CharIterator {
+    fn new(rope: &Rc<Rope>) -> Self {
+        CharIterator(CharWithPointIterator::new(rope))
+    }
+}
+
+impl Iterator for CharIterator {
+    type Item = char;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match self {
+            CharIterator(inner) => inner.next().map(|p| p.character)
+        }
+    }
+}
+
+pub struct CharWithPointIterator {
+    node_iterator: NodeIterator,
+    current_text: Option<String>,
+    str_index: usize,
+    line_num: usize,
+    char_num: usize,
+    eol: bool,
+}
+
+impl CharWithPointIterator {
     fn new(rope: &Rc<Rope>) -> Self {
         let mut node_iterator = NodeIterator::new(rope.clone());
         let current_text = Self::next_string(&mut node_iterator);
-        CharIterator {
+        CharWithPointIterator {
             node_iterator,
             current_text,
             str_index: 0,
+            char_num: 0,
+            line_num: 0,
+            eol: false,
         }
     }
 
@@ -309,18 +340,41 @@ impl CharIterator {
             }
         })
     }
+
+    pub fn get_point(&self) -> (usize, usize) {
+        (self.line_num, self.char_num)
+    }
 }
 
-impl Iterator for CharIterator {
-    type Item = char;
+pub struct CharWithPoint {
+    pub character: char,
+    pub line: usize,
+    pub column: usize,
+}
+
+impl Iterator for CharWithPointIterator {
+    type Item = CharWithPoint;
 
     fn next(&mut self) -> Option<Self::Item> {
         self.current_text
             .as_ref()
             .and_then(|text| {
-                let c = text.chars().nth(self.str_index);
+                let next_char = text.chars().nth(self.str_index);
                 self.str_index += 1;
-                c
+                if let Some(c) = next_char {
+                    if self.eol {
+                        self.char_num = 1;
+                        self.line_num += 1;
+                    } else {
+                        self.char_num += 1
+                    }
+                    self.eol = c == '\n';
+                }
+                next_char.map(|c| CharWithPoint {
+                    character: c,
+                    line: self.line_num,
+                    column: self.char_num,
+                })
             })
             .or_else(|| {
                 self.current_text = Self::next_string(&mut self.node_iterator);
@@ -335,259 +389,4 @@ impl Iterator for CharIterator {
 }
 
 #[cfg(test)]
-mod tests {
-    use super::*;
-    use ntest::timeout;
-
-    fn small_test_rope() -> Rc<Rope> {
-        Rope::join(
-            Rope::join(
-                Rope::join(Rope::new("abc"), Some(Rope::new("def"))),
-                Some(Rope::join(Rope::new("g"), Some(Rope::new("hi")))),
-            ),
-            Some(Rope::join(
-                Rope::join(
-                    Rope::join(Rope::new("jklm"), Some(Rope::new("n"))),
-                    Some(Rope::join(Rope::new("op"), Some(Rope::new("qr")))),
-                ),
-                Some(Rope::join(Rope::new("stuv"), Some(Rope::new("wxyz")))),
-            )),
-        )
-    }
-
-    fn small_test_rope_leaf_strings() -> Vec<&'static str> {
-        vec![
-            "abc", "def", "g", "hi", "jklm", "n", "op", "qr", "stuv", "wxyz",
-        ]
-    }
-
-    fn small_test_rope_full_string() -> &'static str {
-        "abcdefghijklmnopqrstuvwxyz"
-    }
-
-    fn small_test_rope_with_multibyte_chars() -> Rc<Rope> {
-        Rope::join(
-            Rope::join(
-                Rope::join(Rope::new("aあbc"), Some(Rope::new("deえf"))),
-                Some(Rope::join(Rope::new("g"), Some(Rope::new("hiい")))),
-            ),
-            Some(Rope::join(
-                Rope::join(
-                    Rope::join(Rope::new("jklm"), Some(Rope::new("n"))),
-                    Some(Rope::join(Rope::new("おop"), Some(Rope::new("qr")))),
-                ),
-                Some(Rope::join(Rope::new("stuうv"), Some(Rope::new("wxyz")))),
-            )),
-        )
-    }
-
-    fn small_test_rope_with_multibyte_chars_leaf_strings() -> Vec<&'static str> {
-        vec![
-            "aあbc", "deえf", "g", "hiい", "jklm", "n", "おop", "qr", "stuうv", "wxyz",
-        ]
-    }
-
-    fn small_test_rope_with_multibyte_chars_full_string() -> &'static str {
-        "aあbcdeえfghiいjklmnおopqrstuうvwxyz"
-    }
-
-    impl Rope {
-        fn unwrap_branch_left(&self) -> &Rc<Rope> {
-            match self {
-                Rope::Branch { left, .. } => left,
-                Rope::Leaf { .. } => panic!("Expected branch node but found leaf"),
-            }
-        }
-
-        fn unwrap_branch_right(&self) -> Option<&Rc<Rope>> {
-            match self {
-                Rope::Branch { right, .. } => right.as_ref(),
-                Rope::Leaf { .. } => panic!("Expected branch node but found leaf"),
-            }
-        }
-    }
-
-    #[test]
-    #[timeout(100)]
-    fn node_iterator_for_single_node_returns_node_and_only_node() {
-        let target = Rope::new("The");
-
-        let result: Vec<_> = target.iter_nodes().collect();
-        assert_eq!(result.len(), 1);
-        assert_eq!(result[0].total_bytes(), 3);
-        assert_eq!(result[0].total_chars(), 3);
-        assert_eq!(result[0].total_lines(), 1);
-        match result[0].as_ref() {
-            Rope::Leaf { text, .. } => assert_eq!(text, "The"),
-            _ => panic!(),
-        }
-    }
-
-    #[test]
-    #[timeout(100)]
-    fn node_iterator_returns_nodes_in_correct_order() {
-        let strings = small_test_rope_leaf_strings();
-        let target = small_test_rope();
-
-        let result: Vec<_> = target.iter_nodes().take(26).collect();
-        assert_eq!(result.len(), 10);
-        for (node, string) in result.iter().zip(strings) {
-            match &node.as_ref() {
-                Rope::Leaf { text } => assert_eq!(text, string),
-                _ => panic!(),
-            }
-        }
-    }
-
-    #[test]
-    #[timeout(100)]
-    fn char_iterator_returns_chars_in_correct_order() {
-        let target = small_test_rope();
-
-        let result: Vec<_> = target.iter_chars().collect();
-        assert_eq!(result.len(), 26);
-        for (&target_char, expected_char) in
-            result.iter().zip(small_test_rope_full_string().chars())
-        {
-            assert_eq!(target_char, expected_char);
-        }
-    }
-
-    #[test]
-    #[timeout(100)]
-    fn split_splits_at_correct_location() {
-        let target = small_test_rope();
-        let full_string = small_test_rope_full_string();
-        for i in 0..(full_string.chars().count()) {
-            let (first, second) = target.split_at_char_index(i);
-            let first_string: String = first.iter_chars().collect();
-            let second_string: String = second.iter_chars().collect();
-            assert_eq!(first_string, full_string[0..i]);
-            assert_eq!(second_string, full_string[i..]);
-        }
-    }
-
-    #[test]
-    #[timeout(100)]
-    fn split_splits_at_correct_location_with_multibyte_chars() {
-        let target = small_test_rope_with_multibyte_chars();
-        let expected_chars: Vec<_> = small_test_rope_with_multibyte_chars_full_string()
-            .chars()
-            .collect();
-        for i in 0..(expected_chars.len()) {
-            let (first, second) = target.split_at_char_index(i);
-            let string: String = first.iter_chars().collect();
-            let expected: String = expected_chars[0..i].iter().collect();
-            assert_eq!(string, expected);
-            let string: String = second.iter_chars().collect();
-            let expected: String = expected_chars[i..].iter().collect();
-            assert_eq!(string, expected);
-        }
-    }
-
-    #[test]
-    fn depths_have_correct_values() {
-        let target = small_test_rope_with_multibyte_chars();
-        assert_eq!(target.depth(), 4);
-        assert_eq!(target.unwrap_branch_left().depth(), 2);
-        assert_eq!(target.unwrap_branch_left().unwrap_branch_left().depth(), 1);
-        assert_eq!(
-            target
-                .unwrap_branch_left()
-                .unwrap_branch_left()
-                .unwrap_branch_left()
-                .depth(),
-            0
-        );
-        assert_eq!(
-            target
-                .unwrap_branch_left()
-                .unwrap_branch_left()
-                .unwrap_branch_right()
-                .unwrap()
-                .depth(),
-            0
-        );
-        assert_eq!(
-            target
-                .unwrap_branch_left()
-                .unwrap_branch_right()
-                .unwrap()
-                .depth(),
-            1
-        );
-        assert_eq!(
-            target
-                .unwrap_branch_left()
-                .unwrap_branch_right()
-                .unwrap()
-                .unwrap_branch_left()
-                .depth(),
-            0
-        );
-        assert_eq!(
-            target
-                .unwrap_branch_left()
-                .unwrap_branch_right()
-                .unwrap()
-                .unwrap_branch_right()
-                .unwrap()
-                .depth(),
-            0
-        );
-        assert_eq!(target.unwrap_branch_right().unwrap().depth(), 3);
-        assert_eq!(
-            target
-                .unwrap_branch_right()
-                .unwrap()
-                .unwrap_branch_left()
-                .depth(),
-            2
-        );
-        assert_eq!(
-            target
-                .unwrap_branch_right()
-                .unwrap()
-                .unwrap_branch_right()
-                .unwrap()
-                .depth(),
-            1
-        );
-    }
-
-    #[test]
-    fn insert_at_char_index() {
-        let target = Rope::new("The brown dog");
-        assert_eq!(target.iter_chars().collect::<String>(), "The brown dog");
-        let rope1 = target.insert_at_char_index(4, "quick");
-        assert_eq!(target.iter_chars().collect::<String>(), "The brown dog");
-        assert_eq!(rope1.iter_chars().collect::<String>(), "The quickbrown dog");
-        let rope2 = rope1.insert_at_char_index(9, " ");
-        assert_eq!(target.iter_chars().collect::<String>(), "The brown dog");
-        assert_eq!(rope1.iter_chars().collect::<String>(), "The quickbrown dog");
-        assert_eq!(
-            rope2.iter_chars().collect::<String>(),
-            "The quick brown dog"
-        );
-        let rope3 =
-            rope2.insert_at_char_index("The quick brown dog".len(), " jumps over the lazy fox.");
-        assert_eq!(
-            rope3.iter_chars().collect::<String>(),
-            "The quick brown dog jumps over the lazy fox."
-        );
-    }
-
-    #[test]
-    fn delete_at_char_index() {
-        let target = Rope::new("The quick brown fox jumps over the lazy dog.");
-        let test = target.delete_at_char_index(10, 6);
-        assert_eq!(target.iter_chars().collect::<String>(), "The quick brown fox jumps over the lazy dog.");
-        assert_eq!(test.iter_chars().collect::<String>(), "The quick fox jumps over the lazy dog.");
-        let test = target.delete_at_char_index(0, 4);
-        assert_eq!(target.iter_chars().collect::<String>(), "The quick brown fox jumps over the lazy dog.");
-        assert_eq!(test.iter_chars().collect::<String>(), "quick brown fox jumps over the lazy dog.");
-        let test = target.delete_at_char_index("The quick brown fox jumps over the lazy dog.".len()-5, 5);
-        assert_eq!(target.iter_chars().collect::<String>(), "The quick brown fox jumps over the lazy dog.");
-        assert_eq!(test.iter_chars().collect::<String>(), "The quick brown fox jumps over the lazy");
-    }
-}
+mod tests;

core/src/rope/tests/command_list.rs

@@ -0,0 +1,69 @@
+use super::super::{Rc, Rope};
+use rand::{
+    distributions::{Alphanumeric, DistString},
+    rngs::SmallRng,
+    Rng, SeedableRng,
+};
+
+#[derive(Clone, Debug)]
+pub enum Command {
+    InsertAtCharIndex { index: usize, text: String },
+    DeleteAtCharIndex { index: usize, length: usize },
+}
+
+impl Command {
+    pub fn run(&self, rope: &Rc<Rope>) -> Rc<Rope> {
+        match self {
+            Command::InsertAtCharIndex { index, text } => rope.insert_at_char_index(*index, text),
+            Command::DeleteAtCharIndex { index, length } => {
+                rope.delete_at_char_index(*index, *length)
+            }
+        }
+    }
+
+    pub fn run_on_string(&self, input: String) -> String {
+        match self {
+            Command::InsertAtCharIndex { index, text } => input
+                .chars()
+                .take(*index)
+                .chain(text.chars())
+                .chain(input.chars().skip(*index))
+                .collect(),
+            Command::DeleteAtCharIndex { index, length } => input
+                .chars()
+                .enumerate()
+                .filter(|(i, _)| *i < *index || *i >= index + length)
+                .map(|(_, c)| c)
+                .collect(),
+        }
+    }
+}
+
+// TODO: Alphanumeric only samples ASCII
+pub fn generate_random_edit_sequence_with_seed(
+    length: usize,
+    seed: u64,
+) -> (String, Vec<(Command, String)>) {
+    let mut rng = SmallRng::seed_from_u64(seed);
+    let start_text_length = rng.gen_range(0..4000);
+    let start_text = Alphanumeric.sample_string(&mut rng, start_text_length);
+    let num_steps = rng.gen_range(0..1000);
+    let mut steps = Vec::with_capacity(num_steps);
+    let mut current_text = start_text.clone();
+    for i in 0..num_steps {
+        let current_text_length = current_text.len();
+        let command = if rng.gen_bool(0.7) || current_text_length > 0 {
+            let index = rng.gen_range(0..current_text_length);
+            let text_len = rng.gen_range(0..100);
+            let text = Alphanumeric.sample_string(&mut rng, text_len);
+            Command::InsertAtCharIndex { index, text }
+        } else {
+            let index = rng.gen_range(0..current_text_length-1);
+            let length = rng.gen_range(1..(current_text_length - index));
+            Command::DeleteAtCharIndex { index, length }
+        };
+        current_text = command.run_on_string(current_text);
+        steps.push((command.clone(), current_text.clone()));
+    }
+    (start_text, steps)
+}

core/src/rope/tests/mod.rs

@@ -0,0 +1,566 @@
+use super::*;
+use ntest::timeout;
+
+mod command_list;
+
+fn small_test_rope() -> Rc<Rope> {
+    Rope::join(
+        Rope::join(
+            Rope::join(Rope::new("abc"), Some(Rope::new("def"))),
+            Some(Rope::join(Rope::new("g"), Some(Rope::new("hi")))),
+        ),
+        Some(Rope::join(
+            Rope::join(
+                Rope::join(Rope::new("jklm"), Some(Rope::new("n"))),
+                Some(Rope::join(Rope::new("op"), Some(Rope::new("qr")))),
+            ),
+            Some(Rope::join(Rope::new("stuv"), Some(Rope::new("wxyz")))),
+        )),
+    )
+}
+
+fn small_test_rope_leaf_strings() -> Vec<&'static str> {
+    vec![
+        "abc", "def", "g", "hi", "jklm", "n", "op", "qr", "stuv", "wxyz",
+    ]
+}
+
+fn small_test_rope_full_string() -> &'static str {
+    "abcdefghijklmnopqrstuvwxyz"
+}
+
+fn small_test_rope_with_multibyte_chars() -> Rc<Rope> {
+    Rope::join(
+        Rope::join(
+            Rope::join(Rope::new("aあbc"), Some(Rope::new("deえf"))),
+            Some(Rope::join(Rope::new("g"), Some(Rope::new("hiい")))),
+        ),
+        Some(Rope::join(
+            Rope::join(
+                Rope::join(Rope::new("jklm"), Some(Rope::new("n"))),
+                Some(Rope::join(Rope::new("おop"), Some(Rope::new("qr")))),
+            ),
+            Some(Rope::join(Rope::new("stuうv"), Some(Rope::new("wxyz")))),
+        )),
+    )
+}
+
+fn small_test_rope_with_multibyte_chars_leaf_strings() -> Vec<&'static str> {
+    vec![
+        "aあbc", "deえf", "g", "hiい", "jklm", "n", "おop", "qr", "stuうv", "wxyz",
+    ]
+}
+
+fn small_test_rope_with_multibyte_chars_full_string() -> &'static str {
+    "aあbcdeえfghiいjklmnおopqrstuうvwxyz"
+}
+
+impl Rope {
+    fn unwrap_branch_left(&self) -> &Rc<Rope> {
+        match self {
+            Rope::Branch { left, .. } => left,
+            Rope::Leaf { .. } => panic!("Expected branch node but found leaf"),
+        }
+    }
+
+    fn unwrap_branch_right(&self) -> Option<&Rc<Rope>> {
+        match self {
+            Rope::Branch { right, .. } => right.as_ref(),
+            Rope::Leaf { .. } => panic!("Expected branch node but found leaf"),
+        }
+    }
+}
+
+#[test]
+#[timeout(100)]
+fn node_iterator_for_single_node_returns_node_and_only_node() {
+    let target = Rope::new("The");
+
+    let result: Vec<_> = target.iter_nodes().collect();
+    assert_eq!(result.len(), 1);
+    assert_eq!(result[0].total_bytes(), 3);
+    assert_eq!(result[0].total_chars(), 3);
+    assert_eq!(result[0].total_lines(), 1);
+    match result[0].as_ref() {
+        Rope::Leaf { text, .. } => assert_eq!(text, "The"),
+        _ => panic!(),
+    }
+}
+
+#[test]
+#[timeout(100)]
+fn node_iterator_returns_nodes_in_correct_order() {
+    let strings = small_test_rope_leaf_strings();
+    let target = small_test_rope();
+
+    let result: Vec<_> = target.iter_nodes().take(26).collect();
+    assert_eq!(result.len(), 10);
+    for (node, string) in result.iter().zip(strings) {
+        match &node.as_ref() {
+            Rope::Leaf { text } => assert_eq!(text, string),
+            _ => panic!(),
+        }
+    }
+}
+
+#[test]
+#[timeout(100)]
+fn char_iterator_returns_chars_in_correct_order() {
+    let target = small_test_rope();
+
+    let result: Vec<_> = target.iter_chars().collect();
+    assert_eq!(result.len(), 26);
+    for (&target_char, expected_char) in result.iter().zip(small_test_rope_full_string().chars()) {
+        assert_eq!(target_char, expected_char);
+    }
+}
+
+#[test]
+#[timeout(100)]
+fn split_splits_at_correct_location() {
+    let target = small_test_rope();
+    let full_string = small_test_rope_full_string();
+    for i in 0..(full_string.chars().count()) {
+        let (first, second) = target.split_at_char_index(i);
+        let first_string: String = first.iter_chars().collect();
+        let second_string: String = second.iter_chars().collect();
+        assert_eq!(first_string, full_string[0..i]);
+        assert_eq!(second_string, full_string[i..]);
+    }
+}
+
+#[test]
+#[timeout(100)]
+fn split_splits_at_correct_location_with_multibyte_chars() {
+    let target = small_test_rope_with_multibyte_chars();
+    let expected_chars: Vec<_> = small_test_rope_with_multibyte_chars_full_string()
+        .chars()
+        .collect();
+    for i in 0..(expected_chars.len()) {
+        let (first, second) = target.split_at_char_index(i);
+        let string: String = first.iter_chars().collect();
+        let expected: String = expected_chars[0..i].iter().collect();
+        assert_eq!(string, expected);
+        let string: String = second.iter_chars().collect();
+        let expected: String = expected_chars[i..].iter().collect();
+        assert_eq!(string, expected);
+    }
+}
+
+#[test]
+fn depths_have_correct_values() {
+    let target = small_test_rope_with_multibyte_chars();
+    assert_eq!(target.depth(), 4);
+    assert_eq!(target.unwrap_branch_left().depth(), 2);
+    assert_eq!(target.unwrap_branch_left().unwrap_branch_left().depth(), 1);
+    assert_eq!(
+        target
+            .unwrap_branch_left()
+            .unwrap_branch_left()
+            .unwrap_branch_left()
+            .depth(),
+        0
+    );
+    assert_eq!(
+        target
+            .unwrap_branch_left()
+            .unwrap_branch_left()
+            .unwrap_branch_right()
+            .unwrap()
+            .depth(),
+        0
+    );
+    assert_eq!(
+        target
+            .unwrap_branch_left()
+            .unwrap_branch_right()
+            .unwrap()
+            .depth(),
+        1
+    );
+    assert_eq!(
+        target
+            .unwrap_branch_left()
+            .unwrap_branch_right()
+            .unwrap()
+            .unwrap_branch_left()
+            .depth(),
+        0
+    );
+    assert_eq!(
+        target
+            .unwrap_branch_left()
+            .unwrap_branch_right()
+            .unwrap()
+            .unwrap_branch_right()
+            .unwrap()
+            .depth(),
+        0
+    );
+    assert_eq!(target.unwrap_branch_right().unwrap().depth(), 3);
+    assert_eq!(
+        target
+            .unwrap_branch_right()
+            .unwrap()
+            .unwrap_branch_left()
+            .depth(),
+        2
+    );
+    assert_eq!(
+        target
+            .unwrap_branch_right()
+            .unwrap()
+            .unwrap_branch_right()
+            .unwrap()
+            .depth(),
+        1
+    );
+}
+
+#[test]
+fn insert_at_char_index() {
+    let target = Rope::new("The brown dog");
+    assert_eq!(target.iter_chars().collect::<String>(), "The brown dog");
+    let rope1 = target.insert_at_char_index(4, "quick");
+    assert_eq!(target.iter_chars().collect::<String>(), "The brown dog");
+    assert_eq!(rope1.iter_chars().collect::<String>(), "The quickbrown dog");
+    let rope2 = rope1.insert_at_char_index(9, " ");
+    assert_eq!(target.iter_chars().collect::<String>(), "The brown dog");
+    assert_eq!(rope1.iter_chars().collect::<String>(), "The quickbrown dog");
+    assert_eq!(
+        rope2.iter_chars().collect::<String>(),
+        "The quick brown dog"
+    );
+    let rope3 =
+        rope2.insert_at_char_index("The quick brown dog".len(), " jumps over the lazy fox.");
+    assert_eq!(
+        rope3.iter_chars().collect::<String>(),
+        "The quick brown dog jumps over the lazy fox."
+    );
+}
+
+#[test]
+fn delete_at_char_index() {
+    let target = Rope::new("The quick brown fox jumps over the lazy dog.");
+    let test = target.delete_at_char_index(10, 6);
+    assert_eq!(
+        target.iter_chars().collect::<String>(),
+        "The quick brown fox jumps over the lazy dog."
+    );
+    assert_eq!(
+        test.iter_chars().collect::<String>(),
+        "The quick fox jumps over the lazy dog."
+    );
+    let test = target.delete_at_char_index(0, 4);
+    assert_eq!(
+        target.iter_chars().collect::<String>(),
+        "The quick brown fox jumps over the lazy dog."
+    );
+    assert_eq!(
+        test.iter_chars().collect::<String>(),
+        "quick brown fox jumps over the lazy dog."
+    );
+    let test =
+        target.delete_at_char_index("The quick brown fox jumps over the lazy dog.".len() - 5, 5);
+    assert_eq!(
+        target.iter_chars().collect::<String>(),
+        "The quick brown fox jumps over the lazy dog."
+    );
+    assert_eq!(
+        test.iter_chars().collect::<String>(),
+        "The quick brown fox jumps over the lazy"
+    );
+}
+
+#[test]
+fn char_iterator_reports_correct_point() {
+    // Build a rope from fragments so we get a proper tree structure.
+    let target = Rope::new("This")
+        .concat(Rope::new(" is the first "))
+        .concat(Rope::new("line.\n"))
+        .concat(Rope::new("This is the "))
+        .concat(Rope::new("second line.\nThis is the third line."))
+        .concat(Rope::new("\n"))
+        .concat(Rope::new(
+            "This is the fourth line.\nThis is the fifth line.\nThis is ",
+        ))
+        .concat(Rope::new("the"))
+        .concat(Rope::new(" sixth"))
+        .concat(Rope::new(" line."))
+        .concat(Rope::new("\nThis"))
+        .concat(Rope::new(" is the seventh line."));
+    let expected_values = vec![
+        ('T', 0, 1),
+        ('h', 0, 2),
+        ('i', 0, 3),
+        ('s', 0, 4),
+        (' ', 0, 5),
+        ('i', 0, 6),
+        ('s', 0, 7),
+        (' ', 0, 8),
+        ('t', 0, 9),
+        ('h', 0, 10),
+        ('e', 0, 11),
+        (' ', 0, 12),
+        ('f', 0, 13),
+        ('i', 0, 14),
+        ('r', 0, 15),
+        ('s', 0, 16),
+        ('t', 0, 17),
+        (' ', 0, 18),
+        ('l', 0, 19),
+        ('i', 0, 20),
+        ('n', 0, 21),
+        ('e', 0, 22),
+        ('.', 0, 23),
+        ('\n', 0, 24),
+        ('T', 1, 1),
+        ('h', 1, 2),
+        ('i', 1, 3),
+        ('s', 1, 4),
+        (' ', 1, 5),
+        ('i', 1, 6),
+        ('s', 1, 7),
+        (' ', 1, 8),
+        ('t', 1, 9),
+        ('h', 1, 10),
+        ('e', 1, 11),
+        (' ', 1, 12),
+        ('s', 1, 13),
+        ('e', 1, 14),
+        ('c', 1, 15),
+        ('o', 1, 16),
+        ('n', 1, 17),
+        ('d', 1, 18),
+        (' ', 1, 19),
+        ('l', 1, 20),
+        ('i', 1, 21),
+        ('n', 1, 22),
+        ('e', 1, 23),
+        ('.', 1, 24),
+        ('\n', 1, 25),
+        ('T', 2, 1),
+        ('h', 2, 2),
+        ('i', 2, 3),
+        ('s', 2, 4),
+        (' ', 2, 5),
+        ('i', 2, 6),
+        ('s', 2, 7),
+        (' ', 2, 8),
+        ('t', 2, 9),
+        ('h', 2, 10),
+        ('e', 2, 11),
+        (' ', 2, 12),
+        ('t', 2, 13),
+        ('h', 2, 14),
+        ('i', 2, 15),
+        ('r', 2, 16),
+        ('d', 2, 17),
+        (' ', 2, 18),
+        ('l', 2, 19),
+        ('i', 2, 20),
+        ('n', 2, 21),
+        ('e', 2, 22),
+        ('.', 2, 23),
+        ('\n', 2, 24),
+        ('T', 3, 1),
+        ('h', 3, 2),
+        ('i', 3, 3),
+        ('s', 3, 4),
+        (' ', 3, 5),
+        ('i', 3, 6),
+        ('s', 3, 7),
+        (' ', 3, 8),
+        ('t', 3, 9),
+        ('h', 3, 10),
+        ('e', 3, 11),
+        (' ', 3, 12),
+        ('f', 3, 13),
+        ('o', 3, 14),
+        ('u', 3, 15),
+        ('r', 3, 16),
+        ('t', 3, 17),
+        ('h', 3, 18),
+        (' ', 3, 19),
+        ('l', 3, 20),
+        ('i', 3, 21),
+        ('n', 3, 22),
+        ('e', 3, 23),
+        ('.', 3, 24),
+        ('\n', 3, 25),
+        ('T', 4, 1),
+        ('h', 4, 2),
+        ('i', 4, 3),
+        ('s', 4, 4),
+        (' ', 4, 5),
+        ('i', 4, 6),
+        ('s', 4, 7),
+        (' ', 4, 8),
+        ('t', 4, 9),
+        ('h', 4, 10),
+        ('e', 4, 11),
+        (' ', 4, 12),
+        ('f', 4, 13),
+        ('i', 4, 14),
+        ('f', 4, 15),
+        ('t', 4, 16),
+        ('h', 4, 17),
+        (' ', 4, 18),
+        ('l', 4, 19),
+        ('i', 4, 20),
+        ('n', 4, 21),
+        ('e', 4, 22),
+        ('.', 4, 23),
+        ('\n', 4, 24),
+        ('T', 5, 1),
+        ('h', 5, 2),
+        ('i', 5, 3),
+        ('s', 5, 4),
+        (' ', 5, 5),
+        ('i', 5, 6),
+        ('s', 5, 7),
+        (' ', 5, 8),
+        ('t', 5, 9),
+        ('h', 5, 10),
+        ('e', 5, 11),
+        (' ', 5, 12),
+        ('s', 5, 13),
+        ('i', 5, 14),
+        ('x', 5, 15),
+        ('t', 5, 16),
+        ('h', 5, 17),
+        (' ', 5, 18),
+        ('l', 5, 19),
+        ('i', 5, 20),
+        ('n', 5, 21),
+        ('e', 5, 22),
+        ('.', 5, 23),
+        ('\n', 5, 24),
+        ('T', 6, 1),
+        ('h', 6, 2),
+        ('i', 6, 3),
+        ('s', 6, 4),
+        (' ', 6, 5),
+        ('i', 6, 6),
+        ('s', 6, 7),
+        (' ', 6, 8),
+        ('t', 6, 9),
+        ('h', 6, 10),
+        ('e', 6, 11),
+        (' ', 6, 12),
+        ('s', 6, 13),
+        ('e', 6, 14),
+        ('v', 6, 15),
+        ('e', 6, 16),
+        ('n', 6, 17),
+        ('t', 6, 18),
+        ('h', 6, 19),
+        (' ', 6, 20),
+        ('l', 6, 21),
+        ('i', 6, 22),
+        ('n', 6, 23),
+        ('e', 6, 24),
+        ('.', 6, 25),
+        ('\n', 7, 26),
+    ];
+    for (found, (expected_char, expected_line, expected_column)) in
+        target.iter_chars_with_point().zip(expected_values)
+    {
+        assert_eq!(found.character, expected_char);
+        assert_eq!(found.line, expected_line);
+        assert_eq!(found.column, expected_column);
+    }
+}
+
+// Run multiple tests with different seeds so that `cargo test` will run them in
+// parallel.
+// TODO: This could use a macro to generate the list of tests.
+fn random_insertions_and_deletions_with_seed(seed: u64) {
+    let (start_text, edits) = command_list::generate_random_edit_sequence_with_seed(1000, seed);
+    let mut target = Rope::new(start_text);
+    for (command, expected_text) in edits {
+        println!("{:?}", command);
+        target = command.run(&target);
+        assert_eq!(expected_text, target.iter_chars().collect::<String>());
+    }
+}
+
+#[test]
+fn random_insertions_and_deletions_1() {
+    random_insertions_and_deletions_with_seed(0x1234567890ab0001);
+}
+
+#[test]
+fn random_insertions_and_deletions_2() {
+    random_insertions_and_deletions_with_seed(0x1234567890ab0002);
+}
+
+#[test]
+fn random_insertions_and_deletions_3() {
+    random_insertions_and_deletions_with_seed(0x1234567890ab0003);
+}
+
+#[test]
+fn random_insertions_and_deletions_4() {
+    random_insertions_and_deletions_with_seed(0x1234567890ab0004);
+}
+
+#[test]
+fn random_insertions_and_deletions_5() {
+    random_insertions_and_deletions_with_seed(0x1234567890ab0005);
+}
+
+#[test]
+fn random_insertions_and_deletions_6() {
+    random_insertions_and_deletions_with_seed(0x1234567890ab0006);
+}
+
+#[test]
+fn random_insertions_and_deletions_7() {
+    random_insertions_and_deletions_with_seed(0x1234567890ab0007);
+}
+
+#[test]
+fn random_insertions_and_deletions_8() {
+    random_insertions_and_deletions_with_seed(0x1234567890ab0008);
+}
+
+#[test]
+fn random_insertions_and_deletions_9() {
+    random_insertions_and_deletions_with_seed(0x1234567890ab0009);
+}
+
+#[test]
+fn random_insertions_and_deletions_10() {
+    random_insertions_and_deletions_with_seed(0x1234567890ab0010);
+}
+
+#[test]
+fn random_insertions_and_deletions_11() {
+    random_insertions_and_deletions_with_seed(0x1234567890ab0011);
+}
+
+#[test]
+fn random_insertions_and_deletions_12() {
+    random_insertions_and_deletions_with_seed(0x1234567890ab0012);
+}
+
+#[test]
+fn random_insertions_and_deletions_13() {
+    random_insertions_and_deletions_with_seed(0x1234567890ab0013);
+}
+
+#[test]
+fn random_insertions_and_deletions_14() {
+    random_insertions_and_deletions_with_seed(0x1234567890ab0014);
+}
+
+#[test]
+fn random_insertions_and_deletions_15() {
+    random_insertions_and_deletions_with_seed(0x1234567890ab0015);
+}
+
+#[test]
+fn random_insertions_and_deletions_16() {
+    random_insertions_and_deletions_with_seed(0x1234567890ab0016);
+}

src/main.rs

@@ -1,5 +0,0 @@
-mod core;
-
-fn main() {
-    println!("Hello, world!");
-}