2 files changed, 132 insertions, 106 deletions

diff --git a/crates/ra_editor/src/line_index.rs b/crates/ra_editor/src/line_index.rs
index b01760313..5304fbcf6 100644
--- a/crates/ra_editor/src/line_index.rs
+++ b/crates/ra_editor/src/line_index.rs
@@ -128,7 +128,8 @@ impl LineIndex {
     }
 }
 
-// for bench and test
+/// Simple reference implementation to use in proptests
+/// and benchmarks as baseline
 pub fn to_line_col(text: &str, offset: TextUnit) -> LineCol {
     let mut res = LineCol {
         line: 0,
@@ -150,111 +151,135 @@ pub fn to_line_col(text: &str, offset: TextUnit) -> LineCol {
     res
 }
 
-#[test]
-fn test_line_index() {
-    let text = "hello\nworld";
-    let index = LineIndex::new(text);
-    assert_eq!(
-        index.line_col(0.into()),
-        LineCol {
-            line: 0,
-            col_utf16: 0
-        }
-    );
-    assert_eq!(
-        index.line_col(1.into()),
-        LineCol {
-            line: 0,
-            col_utf16: 1
-        }
-    );
-    assert_eq!(
-        index.line_col(5.into()),
-        LineCol {
-            line: 0,
-            col_utf16: 5
-        }
-    );
-    assert_eq!(
-        index.line_col(6.into()),
-        LineCol {
-            line: 1,
-            col_utf16: 0
-        }
-    );
-    assert_eq!(
-        index.line_col(7.into()),
-        LineCol {
-            line: 1,
-            col_utf16: 1
-        }
-    );
-    assert_eq!(
-        index.line_col(8.into()),
-        LineCol {
-            line: 1,
-            col_utf16: 2
-        }
-    );
-    assert_eq!(
-        index.line_col(10.into()),
-        LineCol {
-            line: 1,
-            col_utf16: 4
-        }
-    );
-    assert_eq!(
-        index.line_col(11.into()),
-        LineCol {
-            line: 1,
-            col_utf16: 5
-        }
-    );
-    assert_eq!(
-        index.line_col(12.into()),
-        LineCol {
-            line: 1,
-            col_utf16: 6
-        }
-    );
+#[cfg(test)]
+mod test_line_index {
+    use super::*;
+    use proptest::{prelude::*, proptest, proptest_helper};
+    use ra_text_edit::test_utils::{arb_text, arb_offset};
 
-    let text = "\nhello\nworld";
-    let index = LineIndex::new(text);
-    assert_eq!(
-        index.line_col(0.into()),
-        LineCol {
-            line: 0,
-            col_utf16: 0
-        }
-    );
-    assert_eq!(
-        index.line_col(1.into()),
-        LineCol {
-            line: 1,
-            col_utf16: 0
-        }
-    );
-    assert_eq!(
-        index.line_col(2.into()),
-        LineCol {
-            line: 1,
-            col_utf16: 1
-        }
-    );
-    assert_eq!(
-        index.line_col(6.into()),
-        LineCol {
-            line: 1,
-            col_utf16: 5
-        }
-    );
-    assert_eq!(
-        index.line_col(7.into()),
-        LineCol {
-            line: 2,
-            col_utf16: 0
+    #[test]
+    fn test_line_index() {
+        let text = "hello\nworld";
+        let index = LineIndex::new(text);
+        assert_eq!(
+            index.line_col(0.into()),
+            LineCol {
+                line: 0,
+                col_utf16: 0
+            }
+        );
+        assert_eq!(
+            index.line_col(1.into()),
+            LineCol {
+                line: 0,
+                col_utf16: 1
+            }
+        );
+        assert_eq!(
+            index.line_col(5.into()),
+            LineCol {
+                line: 0,
+                col_utf16: 5
+            }
+        );
+        assert_eq!(
+            index.line_col(6.into()),
+            LineCol {
+                line: 1,
+                col_utf16: 0
+            }
+        );
+        assert_eq!(
+            index.line_col(7.into()),
+            LineCol {
+                line: 1,
+                col_utf16: 1
+            }
+        );
+        assert_eq!(
+            index.line_col(8.into()),
+            LineCol {
+                line: 1,
+                col_utf16: 2
+            }
+        );
+        assert_eq!(
+            index.line_col(10.into()),
+            LineCol {
+                line: 1,
+                col_utf16: 4
+            }
+        );
+        assert_eq!(
+            index.line_col(11.into()),
+            LineCol {
+                line: 1,
+                col_utf16: 5
+            }
+        );
+        assert_eq!(
+            index.line_col(12.into()),
+            LineCol {
+                line: 1,
+                col_utf16: 6
+            }
+        );
+
+        let text = "\nhello\nworld";
+        let index = LineIndex::new(text);
+        assert_eq!(
+            index.line_col(0.into()),
+            LineCol {
+                line: 0,
+                col_utf16: 0
+            }
+        );
+        assert_eq!(
+            index.line_col(1.into()),
+            LineCol {
+                line: 1,
+                col_utf16: 0
+            }
+        );
+        assert_eq!(
+            index.line_col(2.into()),
+            LineCol {
+                line: 1,
+                col_utf16: 1
+            }
+        );
+        assert_eq!(
+            index.line_col(6.into()),
+            LineCol {
+                line: 1,
+                col_utf16: 5
+            }
+        );
+        assert_eq!(
+            index.line_col(7.into()),
+            LineCol {
+                line: 2,
+                col_utf16: 0
+            }
+        );
+    }
+
+    fn arb_text_with_offset() -> BoxedStrategy<(TextUnit, String)> {
+        arb_text()
+            .prop_flat_map(|text| (arb_offset(&text), Just(text)))
+            .boxed()
+    }
+
+    proptest! {
+        #[test]
+        fn test_line_index_proptest((offset, text) in arb_text_with_offset()) {
+            let expected = to_line_col(&text, offset);
+            let line_index = LineIndex::new(&text);
+            let actual = line_index.line_col(offset);
+
+            assert_eq!(actual, expected);
         }
-    );
+    }
 }
 
 #[cfg(test)]
@@ -349,4 +374,5 @@ const C: char = \"メ メ\";
 
         assert_eq!(col_index.utf16_to_utf8_col(2, 15), TextUnit::from_usize(15));
     }
+
 }
diff --git a/crates/ra_editor/src/line_index_utils.rs b/crates/ra_editor/src/line_index_utils.rs
index 632c962cc..a0bb9a6dd 100644
--- a/crates/ra_editor/src/line_index_utils.rs
+++ b/crates/ra_editor/src/line_index_utils.rs
@@ -325,7 +325,7 @@ pub fn translate_offset_with_edit(
     res.to_line_col(offset)
 }
 
-// for bench
+/// Simplest implementation to use as reference in proptest and benchmarks
 pub fn translate_after_edit(
     pre_edit_text: &str,
     offset: TextUnit,
@@ -352,8 +352,8 @@ fn edit_text(pre_edit_text: &str, mut edits: Vec<AtomTextEdit>) -> String {
 
 #[cfg(test)]
 mod test {
-    use proptest::{prelude::*, proptest, proptest_helper};
     use super::*;
+    use proptest::{prelude::*, proptest, proptest_helper};
     use ra_text_edit::test_utils::{arb_text, arb_offset, arb_edits};
 
     #[derive(Debug)]