Factor out line ending handling in integration tests (#9921)

Prior to this change, every integration test which wanted its line
endings to be handled transparently across platforms, i.e. test with
the same input that has its platform's line feed characters, converting
the line endings was up to each individual test by calling the
`platform_line` helper function. This significantly increases the amount
of boilerplate one has to copy between all the tests.

However, there are some test cases that need to exert strict control
over the exact input text without being manipulated behind the scenes by
the test framework.

So, with this change, the line feed conversions are factored into
the `TestCase` struct. By default, line endings of the input text
are converted to the platform's native line feed ending, but one can
explicitly specify in their test case when the input text should be left
alone and tested as is.

helix-term/tests/test/helpers.rs

@@ -14,6 +14,46 @@ use helix_view::{current_ref, doc, editor::LspConfig, input::parse_macro, Editor
 use tempfile::NamedTempFile;
 use tokio_stream::wrappers::UnboundedReceiverStream;
 
+/// Specify how to set up the input text with line feeds
+#[derive(Clone, Debug)]
+pub enum LineFeedHandling {
+    /// Replaces all LF chars with the system's appropriate line feed character,
+    /// and if one doesn't exist already, appends the system's appropriate line
+    /// ending to the end of a string.
+    Native,
+
+    /// Do not modify the input text in any way. What you give is what you test.
+    AsIs,
+}
+
+impl LineFeedHandling {
+    /// Apply the line feed handling to the input string, yielding a set of
+    /// resulting texts with the appropriate line feed substitutions.
+    pub fn apply(&self, text: &str) -> String {
+        let line_end = match self {
+            LineFeedHandling::Native => helix_core::NATIVE_LINE_ENDING,
+            LineFeedHandling::AsIs => return text.into(),
+        }
+        .as_str();
+
+        // we can assume that the source files in this code base will always
+        // be LF, so indoc strings will always insert LF
+        let mut output = text.replace('\n', line_end);
+
+        if !output.ends_with(line_end) {
+            output.push_str(line_end);
+        }
+
+        output
+    }
+}
+
+impl Default for LineFeedHandling {
+    fn default() -> Self {
+        Self::Native
+    }
+}
+
 #[derive(Clone, Debug)]
 pub struct TestCase {
     pub in_text: String,
@@ -21,6 +61,8 @@ pub struct TestCase {
     pub in_keys: String,
     pub out_text: String,
     pub out_selection: Selection,
+
+    pub line_feed_handling: LineFeedHandling,
 }
 
 impl<S, R, V> From<(S, R, V)> for TestCase
@@ -30,8 +72,19 @@ where
     V: Into<String>,
 {
     fn from((input, keys, output): (S, R, V)) -> Self {
-        let (in_text, in_selection) = test::print(&input.into());
-        let (out_text, out_selection) = test::print(&output.into());
+        TestCase::from((input, keys, output, LineFeedHandling::default()))
+    }
+}
+
+impl<S, R, V> From<(S, R, V, LineFeedHandling)> for TestCase
+where
+    S: Into<String>,
+    R: Into<String>,
+    V: Into<String>,
+{
+    fn from((input, keys, output, line_feed_handling): (S, R, V, LineFeedHandling)) -> Self {
+        let (in_text, in_selection) = test::print(&line_feed_handling.apply(&input.into()));
+        let (out_text, out_selection) = test::print(&line_feed_handling.apply(&output.into()));
 
         TestCase {
             in_text,
@@ -39,6 +92,7 @@ where
             in_keys: keys.into(),
             out_text,
             out_selection,
+            line_feed_handling,
         }
     }
 }
@@ -137,6 +191,7 @@ pub async fn test_key_sequence_with_input_text<T: Into<TestCase>>(
     should_exit: bool,
 ) -> anyhow::Result<()> {
     let test_case = test_case.into();
+
     let mut app = match app {
         Some(app) => app,
         None => Application::new(Args::default(), test_config(), test_syntax_loader(None))?,
@@ -240,23 +295,6 @@ pub fn test_editor_config() -> helix_view::editor::Config {
     }
 }
 
-/// Replaces all LF chars with the system's appropriate line feed
-/// character, and if one doesn't exist already, appends the system's
-/// appropriate line ending to the end of a string.
-pub fn platform_line(input: &str) -> String {
-    let line_end = helix_core::NATIVE_LINE_ENDING.as_str();
-
-    // we can assume that the source files in this code base will always
-    // be LF, so indoc strings will always insert LF
-    let mut output = input.replace('\n', line_end);
-
-    if !output.ends_with(line_end) {
-        output.push_str(line_end);
-    }
-
-    output
-}
-
 /// Creates a new temporary file that is set to read only. Useful for
 /// testing write failures.
 pub fn new_readonly_tempfile() -> anyhow::Result<NamedTempFile> {