add test for ensuring the initial cursor on a newly opened file

Cargo.lock

@@ -221,6 +221,15 @@ dependencies = [
  "thiserror",
 ]
 
+[[package]]
+name = "fastrand"
+version = "1.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c3fcf0cee53519c866c09b5de1f6c56ff9d647101f81c1964fa632e148896cdf"
+dependencies = [
+ "instant",
+]
+
 [[package]]
 name = "fern"
 version = "0.6.1"
@@ -462,6 +471,7 @@ dependencies = [
  "signal-hook",
  "signal-hook-tokio",
  "smallvec",
+ "tempfile",
  "tokio",
  "tokio-stream",
  "toml",
@@ -555,6 +565,15 @@ dependencies = [
  "unindent",
 ]
 
+[[package]]
+name = "instant"
+version = "0.1.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7a5bbe824c507c5da5956355e86a746d82e0e1464f65d862cc5e71da70e94b2c"
+dependencies = [
+ "cfg-if",
+]
+
 [[package]]
 name = "itoa"
 version = "1.0.1"
@@ -852,6 +871,15 @@ version = "0.6.25"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f497285884f3fcff424ffc933e56d7cbca511def0c9831a7f9b5f6153e3cc89b"
 
+[[package]]
+name = "remove_dir_all"
+version = "0.5.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3acd125665422973a33ac9d3dd2df85edad0f4ae9b00dafb1a05e43a9f5ef8e7"
+dependencies = [
+ "winapi",
+]
+
 [[package]]
 name = "retain_mut"
 version = "0.1.7"
@@ -1056,6 +1084,20 @@ dependencies = [
  "unicode-xid",
 ]
 
+[[package]]
+name = "tempfile"
+version = "3.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5cdb1ef4eaeeaddc8fbd371e5017057064af0911902ef36b39801f67cc6d79e4"
+dependencies = [
+ "cfg-if",
+ "fastrand",
+ "libc",
+ "redox_syscall",
+ "remove_dir_all",
+ "winapi",
+]
+
 [[package]]
 name = "textwrap"
 version = "0.15.0"

helix-term/Cargo.toml

@@ -78,3 +78,4 @@ helix-loader = { version = "0.6", path = "../helix-loader" }
 [dev-dependencies]
 smallvec = "1.8"
 indoc = "1.0.3"
+tempfile = "3.3.0"

helix-term/tests/integration.rs

@@ -25,4 +25,5 @@ async fn hello_world() -> anyhow::Result<()> {
     mod auto_indent;
     mod auto_pairs;
     mod movement;
+    mod write;
 }

helix-term/tests/integration/helpers.rs

@@ -1,3 +1,5 @@
+use std::io::Write;
+
 use crossterm::event::{Event, KeyEvent};
 use helix_core::{test, Selection, Transaction};
 use helix_term::{application::Application, args::Args, config::Config};
@@ -85,3 +87,14 @@ pub fn test_key_sequence_text_result<T: Into<TestCase>>(
 
     Ok(())
 }
+
+pub fn temp_file_with_contents<S: AsRef<str>>(content: S) -> tempfile::NamedTempFile {
+    let mut temp_file = tempfile::NamedTempFile::new().unwrap();
+    temp_file
+        .as_file_mut()
+        .write_all(content.as_ref().as_bytes())
+        .unwrap();
+    temp_file.flush().unwrap();
+    temp_file.as_file_mut().sync_all().unwrap();
+    temp_file
+}

helix-term/tests/integration/movement.rs

@@ -1,3 +1,5 @@
+use helix_term::application::Application;
+
 use super::*;
 
 #[tokio::test]
@@ -94,3 +96,31 @@ async fn insert_to_normal_mode_cursor_position() -> anyhow::Result<()> {
 
     Ok(())
 }
+
+/// Ensure the very initial cursor in an opened file is the width of
+/// the first grapheme
+#[tokio::test]
+async fn cursor_position_newly_opened_file() -> anyhow::Result<()> {
+    let test = |content: &str, expected_sel: Selection| {
+        let file = helpers::temp_file_with_contents(content);
+
+        let mut app = Application::new(
+            Args {
+                files: vec![(file.path().to_path_buf(), Position::default())],
+                ..Default::default()
+            },
+            Config::default(),
+        )
+        .unwrap();
+
+        let (view, doc) = helix_view::current!(app.editor);
+        let sel = doc.selection(view.id).clone();
+        assert_eq!(expected_sel, sel);
+    };
+
+    test("foo", Selection::single(0, 1));
+    test("👨‍👩‍👧‍👦 foo", Selection::single(0, 7));
+    test("", Selection::single(0, 0));
+
+    Ok(())
+}