Line continuations for rust step definitions (#179)

* fix: rust line continuation

* Unit test patterns ending with continuation

CHANGELOG.md

@@ -8,8 +8,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ## [Unreleased]
 ### Fixed
 - (Rust) Support for r# raw strings with step definition patterns ([#176](https://github.com/cucumber/language-service/pull/176))
-
-### Fixed
+- (Rust) Line continuation characters in rust step definition patterns ([#179](https://github.com/cucumber/language-service/pull/179))
 - (Python) Unexpected spaces and commas in generated step definitions [#160](https://github.com/cucumber/language-service/issues/160)
 
 ## [1.4.1] - 2023-07-16

src/language/rustLanguage.ts

@@ -111,9 +111,17 @@ fn {{ #lowercase }}{{ #underscore }}{{ expression }}{{ /underscore }}{{ /lowerca
 
 export function stringLiteral(node: TreeSitterSyntaxNode | null): string {
   if (node === null) throw new Error('node cannot be null')
-  if (node.text.startsWith('r#')) return unescapeString(node.text.slice(3, -2))
-  if (node.text.startsWith('r')) return unescapeString(node.text.slice(2, -1))
-  return unescapeString(node.text.slice(1, -1))
+
+  let result
+  if (node.text.startsWith('r#')) result = unescapeString(node.text.slice(3, -2))
+  else if (node.text.startsWith('r')) result = unescapeString(node.text.slice(2, -1))
+  else result = unescapeString(node.text.slice(1, -1))
+
+  return stripLineContinuation(result)
+}
+
+export function stripLineContinuation(s: string): string {
+  return s.replace(/\\\n\s*/g, '')
 }
 
 function unescapeString(s: string): string {

test/language/rustLanguage.test.ts

@@ -1,6 +1,6 @@
 import assert from 'assert'
 
-import { stringLiteral } from '../../src/language/rustLanguage.js'
+import { stringLiteral, stripLineContinuation } from '../../src/language/rustLanguage.js'
 import { TreeSitterSyntaxNode } from '../../src/language/types.js'
 
 describe('rustLanguage', () => {
@@ -41,4 +41,71 @@ describe('rustLanguage', () => {
       assert.strictEqual(stringLiteral(node), expected)
     })
   })
+
+  it('should strip line continuations from expressions', () => {
+    const cases = [
+      {
+        // Single line continuation
+        input: '"Line \\\n  continuation"',
+        expected: '"Line continuation"',
+      },
+      {
+        input: '"Multiple \\\n  line \\\n  continuations"',
+        expected: '"Multiple line continuations"',
+      },
+      {
+        // Continuation with consecutive new lines
+        input: '"Continuation with \\\n\n  consecutive new lines"',
+        expected: '"Continuation with consecutive new lines"',
+      },
+      {
+        // No space before continuation
+        input: '"No space\\\n  before continuation"',
+        expected: '"No spacebefore continuation"',
+      },
+      {
+        // Multiple spaces before continuation
+        input: '"Two spaces  \\\n  before continuation"',
+        expected: '"Two spaces  before continuation"',
+      },
+      {
+        // Line continuation with extra space
+        input: '"this \\ line \\\nshould too"',
+        expected: '"this \\ line should too"',
+      },
+      {
+        // Ends with line continuation
+        input: '"Ends with continuation\\\n"',
+        expected: '"Ends with continuation"',
+      },
+      {
+        // Ends with line continuation and whitespace
+        input: '"Ends with continuation and whitespace\\\n "',
+        expected: '"Ends with continuation and whitespace"',
+      },
+    ]
+
+    cases.forEach(({ input, expected }) => {
+      assert.strictEqual(stripLineContinuation(input), expected)
+    })
+  })
+
+  it('should not strip invalid line continuations from expressions', () => {
+    const cases = [
+      {
+        // Space after continuation but before new line
+        input: '"Space after continuation \\ \n  but before new line"',
+        expected: '"Space after continuation \\ \n  but before new line"',
+      },
+      {
+        // Ends with escape character
+        input: '"Escaped backslash \\"',
+        expected: '"Escaped backslash \\"',
+      },
+    ]
+
+    cases.forEach(({ input, expected }) => {
+      assert.strictEqual(stripLineContinuation(input), expected)
+    })
+  })
 })