diff --git a/Cargo.lock b/Cargo.lock
index ee50d006c1..3a4929a0f4 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -78,21 +78,6 @@ version = "0.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b41b7ea54a0c9d92199de89e20e58d49f02f8e699814ef3fdf266f6f748d15c7"
 
-[[package]]
-name = "bit-set"
-version = "0.5.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e84c238982c4b1e1ee668d136c510c67a13465279c0cb367ea6baf6310620a80"
-dependencies = [
- "bit-vec",
-]
-
-[[package]]
-name = "bit-vec"
-version = "0.5.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f59bbe95d4e52a6398ec21238d31577f2b28a9d86807f06ca59d191d8440d0bb"
-
 [[package]]
 name = "bitflags"
 version = "1.2.1"
@@ -428,12 +413,6 @@ dependencies = [
  "byteorder",
 ]
 
-[[package]]
-name = "fuchsia-cprng"
-version = "0.1.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a06f77d526c1a601b7c4cdd98f54b5eaabffc14d5f2f0296febdc7f357c6d3ba"
-
 [[package]]
 name = "fuchsia-zircon"
 version = "0.3.3"
@@ -791,15 +770,6 @@ dependencies = [
  "winapi 0.3.8",
 ]
 
-[[package]]
-name = "num-traits"
-version = "0.2.11"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c62be47e61d1842b9170f0fdeec8eba98e60e90e5446449a0545e5152acd7096"
-dependencies = [
- "autocfg 1.0.0",
-]
-
 [[package]]
 name = "num_cpus"
 version = "1.12.0"
@@ -916,30 +886,6 @@ dependencies = [
  "unicode-xid",
 ]
 
-[[package]]
-name = "proptest"
-version = "0.9.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bf6147d103a7c9d7598f4105cf049b15c99e2ecd93179bf024f0fd349be5ada4"
-dependencies = [
- "bit-set",
- "bitflags",
- "byteorder",
- "lazy_static",
- "num-traits",
- "quick-error",
- "rand 0.6.5",
- "rand_chacha 0.1.1",
- "rand_xorshift",
- "regex-syntax",
-]
-
-[[package]]
-name = "quick-error"
-version = "1.2.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a1d01941d82fa2ab50be1e79e6714289dd7cde78eba4c074bc5a4374f650dfe0"
-
 [[package]]
 name = "quote"
 version = "1.0.2"
@@ -1025,7 +971,7 @@ dependencies = [
  "ra_ide",
  "ra_prof",
  "ra_syntax",
- "rand 0.7.3",
+ "rand",
 ]
 
 [[package]]
@@ -1137,7 +1083,6 @@ dependencies = [
  "join_to_string",
  "log",
  "once_cell",
- "proptest",
  "ra_assists",
  "ra_cfg",
  "ra_db",
@@ -1147,7 +1092,7 @@ dependencies = [
  "ra_prof",
  "ra_syntax",
  "ra_text_edit",
- "rand 0.7.3",
+ "rand",
  "rayon",
  "rustc-hash",
  "superslice",
@@ -1168,7 +1113,6 @@ dependencies = [
  "join_to_string",
  "log",
  "once_cell",
- "proptest",
  "ra_cfg",
  "ra_db",
  "ra_fmt",
@@ -1281,7 +1225,6 @@ dependencies = [
 name = "ra_text_edit"
 version = "0.1.0"
 dependencies = [
- "proptest",
  "test_utils",
  "text_unit",
 ]
@@ -1317,25 +1260,6 @@ dependencies = [
  "ra_vfs",
 ]
 
-[[package]]
-name = "rand"
-version = "0.6.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6d71dacdc3c88c1fde3885a3be3fbab9f35724e6ce99467f7d9c5026132184ca"
-dependencies = [
- "autocfg 0.1.7",
- "libc",
- "rand_chacha 0.1.1",
- "rand_core 0.4.2",
- "rand_hc 0.1.0",
- "rand_isaac",
- "rand_jitter",
- "rand_os",
- "rand_pcg 0.1.2",
- "rand_xorshift",
- "winapi 0.3.8",
-]
-
 [[package]]
 name = "rand"
 version = "0.7.3"
@@ -1344,20 +1268,10 @@ checksum = "6a6b1679d49b24bbfe0c803429aa1874472f50d9b363131f0e89fc356b544d03"
 dependencies = [
  "getrandom",
  "libc",
- "rand_chacha 0.2.1",
- "rand_core 0.5.1",
- "rand_hc 0.2.0",
- "rand_pcg 0.2.1",
-]
-
-[[package]]
-name = "rand_chacha"
-version = "0.1.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "556d3a1ca6600bfcbab7c7c91ccb085ac7fbbcd70e008a98742e7847f4f7bcef"
-dependencies = [
- "autocfg 0.1.7",
- "rand_core 0.3.1",
+ "rand_chacha",
+ "rand_core",
+ "rand_hc",
+ "rand_pcg",
 ]
 
 [[package]]
@@ -1367,24 +1281,9 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "03a2a90da8c7523f554344f921aa97283eadf6ac484a6d2a7d0212fa7f8d6853"
 dependencies = [
  "c2-chacha",
- "rand_core 0.5.1",
+ "rand_core",
 ]
 
-[[package]]
-name = "rand_core"
-version = "0.3.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7a6fdeb83b075e8266dcc8762c22776f6877a63111121f5f8c7411e5be7eed4b"
-dependencies = [
- "rand_core 0.4.2",
-]
-
-[[package]]
-name = "rand_core"
-version = "0.4.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9c33a3c44ca05fa6f1807d8e6743f3824e8509beca625669633be0acbdf509dc"
-
 [[package]]
 name = "rand_core"
 version = "0.5.1"
@@ -1394,66 +1293,13 @@ dependencies = [
  "getrandom",
 ]
 
-[[package]]
-name = "rand_hc"
-version = "0.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7b40677c7be09ae76218dc623efbf7b18e34bced3f38883af07bb75630a21bc4"
-dependencies = [
- "rand_core 0.3.1",
-]
-
 [[package]]
 name = "rand_hc"
 version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ca3129af7b92a17112d59ad498c6f81eaf463253766b90396d39ea7a39d6613c"
 dependencies = [
- "rand_core 0.5.1",
-]
-
-[[package]]
-name = "rand_isaac"
-version = "0.1.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ded997c9d5f13925be2a6fd7e66bf1872597f759fd9dd93513dd7e92e5a5ee08"
-dependencies = [
- "rand_core 0.3.1",
-]
-
-[[package]]
-name = "rand_jitter"
-version = "0.1.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1166d5c91dc97b88d1decc3285bb0a99ed84b05cfd0bc2341bdf2d43fc41e39b"
-dependencies = [
- "libc",
- "rand_core 0.4.2",
- "winapi 0.3.8",
-]
-
-[[package]]
-name = "rand_os"
-version = "0.1.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7b75f676a1e053fc562eafbb47838d67c84801e38fc1ba459e8f180deabd5071"
-dependencies = [
- "cloudabi",
- "fuchsia-cprng",
- "libc",
- "rand_core 0.4.2",
- "rdrand",
- "winapi 0.3.8",
-]
-
-[[package]]
-name = "rand_pcg"
-version = "0.1.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "abf9b09b01790cfe0364f52bf32995ea3c39f4d2dd011eac241d2914146d0b44"
-dependencies = [
- "autocfg 0.1.7",
- "rand_core 0.4.2",
+ "rand_core",
 ]
 
 [[package]]
@@ -1462,16 +1308,7 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "16abd0c1b639e9eb4d7c50c0b8100b0d0f849be2349829c740fe8e6eb4816429"
 dependencies = [
- "rand_core 0.5.1",
-]
-
-[[package]]
-name = "rand_xorshift"
-version = "0.1.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cbf7e9e623549b0e21f6e97cf8ecf247c1a8fd2e8a992ae265314300b2455d5c"
-dependencies = [
- "rand_core 0.3.1",
+ "rand_core",
 ]
 
 [[package]]
@@ -1498,15 +1335,6 @@ dependencies = [
  "num_cpus",
 ]
 
-[[package]]
-name = "rdrand"
-version = "0.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "678054eb77286b51581ba43620cc911abf02758c91f93f479767aed0f90458b2"
-dependencies = [
- "rand_core 0.3.1",
-]
-
 [[package]]
 name = "redox_syscall"
 version = "0.1.56"
@@ -1604,7 +1432,7 @@ dependencies = [
  "indexmap",
  "log",
  "parking_lot",
- "rand 0.7.3",
+ "rand",
  "rustc-hash",
  "salsa-macros",
  "smallvec",
@@ -1753,7 +1581,7 @@ checksum = "7a6e24d9338a0a5be79593e2fa15a648add6138caa803e2d5bc782c371732ca9"
 dependencies = [
  "cfg-if",
  "libc",
- "rand 0.7.3",
+ "rand",
  "redox_syscall",
  "remove_dir_all",
  "winapi 0.3.8",
diff --git a/crates/ra_ide/Cargo.toml b/crates/ra_ide/Cargo.toml
index 9ace35229d..d50cf1d20a 100644
--- a/crates/ra_ide/Cargo.toml
+++ b/crates/ra_ide/Cargo.toml
@@ -41,9 +41,3 @@ hir = { path = "../ra_hir", package = "ra_hir" }
 
 [dev-dependencies]
 insta = "0.13.0"
-
-[dev-dependencies.proptest]
-version = "0.9.0"
-# Disable `fork` feature to allow compiling on webassembly
-default-features = false
-features = ["std", "bit-set", "break-dead-code"]
diff --git a/crates/ra_ide_db/Cargo.toml b/crates/ra_ide_db/Cargo.toml
index 495fffb5af..ad3acce595 100644
--- a/crates/ra_ide_db/Cargo.toml
+++ b/crates/ra_ide_db/Cargo.toml
@@ -38,9 +38,3 @@ hir = { path = "../ra_hir", package = "ra_hir" }
 
 [dev-dependencies]
 insta = "0.13.0"
-
-[dev-dependencies.proptest]
-version = "0.9.0"
-# Disable `fork` feature to allow compiling on webassembly
-default-features = false
-features = ["std", "bit-set", "break-dead-code"]
diff --git a/crates/ra_ide_db/src/line_index.rs b/crates/ra_ide_db/src/line_index.rs
index 452c87ac51..af7b759e5c 100644
--- a/crates/ra_ide_db/src/line_index.rs
+++ b/crates/ra_ide_db/src/line_index.rs
@@ -124,31 +124,9 @@ impl LineIndex {
     }
 }
 
-#[cfg(test)]
-/// Simple reference implementation to use in proptests
-pub fn to_line_col(text: &str, offset: TextUnit) -> LineCol {
-    let mut res = LineCol { line: 0, col_utf16: 0 };
-    for (i, c) in text.char_indices() {
-        if i + c.len_utf8() > offset.to_usize() {
-            // if it's an invalid offset, inside a multibyte char
-            // return as if it was at the start of the char
-            break;
-        }
-        if c == '\n' {
-            res.line += 1;
-            res.col_utf16 = 0;
-        } else {
-            res.col_utf16 += 1;
-        }
-    }
-    res
-}
-
 #[cfg(test)]
 mod test_line_index {
     use super::*;
-    use proptest::{prelude::*, proptest};
-    use ra_text_edit::test_utils::{arb_offset, arb_text};
 
     #[test]
     fn test_line_index() {
@@ -173,44 +151,6 @@ mod test_line_index {
         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()
-    }
-
-    fn to_line_col(text: &str, offset: TextUnit) -> LineCol {
-        let mut res = LineCol { line: 0, col_utf16: 0 };
-        for (i, c) in text.char_indices() {
-            if i + c.len_utf8() > offset.to_usize() {
-                // if it's an invalid offset, inside a multibyte char
-                // return as if it was at the start of the char
-                break;
-            }
-            if c == '\n' {
-                res.line += 1;
-                res.col_utf16 = 0;
-            } else {
-                res.col_utf16 += 1;
-            }
-        }
-        res
-    }
-
-    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)]
-mod test_utf8_utf16_conv {
-    use super::*;
-
     #[test]
     fn test_char_len() {
         assert_eq!('メ'.len_utf8(), 3);
diff --git a/crates/ra_ide_db/src/line_index_utils.rs b/crates/ra_ide_db/src/line_index_utils.rs
index 435b065116..75a498151f 100644
--- a/crates/ra_ide_db/src/line_index_utils.rs
+++ b/crates/ra_ide_db/src/line_index_utils.rs
@@ -297,45 +297,3 @@ impl RunningLineCol {
         self.col_adjust += range.len() - TextUnit::from(1);
     }
 }
-
-#[cfg(test)]
-mod test {
-    use proptest::{prelude::*, proptest};
-    use ra_text_edit::test_utils::{arb_offset, arb_text_with_edit};
-    use ra_text_edit::TextEdit;
-
-    use crate::line_index;
-
-    use super::*;
-
-    #[derive(Debug)]
-    struct ArbTextWithEditAndOffset {
-        text: String,
-        edit: TextEdit,
-        edited_text: String,
-        offset: TextUnit,
-    }
-
-    fn arb_text_with_edit_and_offset() -> BoxedStrategy<ArbTextWithEditAndOffset> {
-        arb_text_with_edit()
-            .prop_flat_map(|x| {
-                let edited_text = x.edit.apply(&x.text);
-                let arb_offset = arb_offset(&edited_text);
-                (Just(x), Just(edited_text), arb_offset).prop_map(|(x, edited_text, offset)| {
-                    ArbTextWithEditAndOffset { text: x.text, edit: x.edit, edited_text, offset }
-                })
-            })
-            .boxed()
-    }
-
-    proptest! {
-        #[test]
-        fn test_translate_offset_with_edit(x in arb_text_with_edit_and_offset()) {
-            let expected = line_index::to_line_col(&x.edited_text, x.offset);
-            let line_index = LineIndex::new(&x.text);
-            let actual = translate_offset_with_edit(&line_index, x.offset, &x.edit);
-
-            assert_eq!(actual, expected);
-        }
-    }
-}
diff --git a/crates/ra_text_edit/Cargo.toml b/crates/ra_text_edit/Cargo.toml
index 8573c521a2..4490ae43bc 100644
--- a/crates/ra_text_edit/Cargo.toml
+++ b/crates/ra_text_edit/Cargo.toml
@@ -11,11 +11,5 @@ doctest = false
 [dependencies]
 text_unit = "0.1.6"
 
-[dependencies.proptest]
-version = "0.9.0"
-# Disable `fork` feature to allow compiling on webassembly
-default-features = false
-features = ["std", "bit-set", "break-dead-code"]
-
 [dev-dependencies]
 test_utils = { path = "../test_utils" }
diff --git a/crates/ra_text_edit/src/lib.rs b/crates/ra_text_edit/src/lib.rs
index 37f23d0438..f6769e6a64 100644
--- a/crates/ra_text_edit/src/lib.rs
+++ b/crates/ra_text_edit/src/lib.rs
@@ -1,12 +1,11 @@
 //! FIXME: write short doc here
 
 mod text_edit;
-pub mod test_utils;
-
-pub use crate::text_edit::{TextEdit, TextEditBuilder};
 
 use text_unit::{TextRange, TextUnit};
 
+pub use crate::text_edit::{TextEdit, TextEditBuilder};
+
 /// Must not overlap with other `AtomTextEdit`s
 #[derive(Debug, Clone)]
 pub struct AtomTextEdit {
diff --git a/crates/ra_text_edit/src/test_utils.rs b/crates/ra_text_edit/src/test_utils.rs
deleted file mode 100644
index d4c7840ffa..0000000000
--- a/crates/ra_text_edit/src/test_utils.rs
+++ /dev/null
@@ -1,83 +0,0 @@
-//! FIXME: write short doc here
-
-use crate::{AtomTextEdit, TextEdit};
-use proptest::prelude::*;
-use text_unit::{TextRange, TextUnit};
-
-pub fn arb_text() -> proptest::string::RegexGeneratorStrategy<String> {
-    // generate multiple newlines
-    proptest::string::string_regex("(.*\n?)*").unwrap()
-}
-
-fn text_offsets(text: &str) -> Vec<TextUnit> {
-    text.char_indices().map(|(i, _)| TextUnit::from_usize(i)).collect()
-}
-
-pub fn arb_offset(text: &str) -> BoxedStrategy<TextUnit> {
-    let offsets = text_offsets(text);
-    // this is necessary to avoid "Uniform::new called with `low >= high`" panic
-    if offsets.is_empty() {
-        Just(TextUnit::from(0)).boxed()
-    } else {
-        prop::sample::select(offsets).boxed()
-    }
-}
-
-pub fn arb_text_edit(text: &str) -> BoxedStrategy<TextEdit> {
-    if text.is_empty() {
-        // only valid edits
-        return Just(vec![])
-            .boxed()
-            .prop_union(
-                arb_text()
-                    .prop_map(|text| vec![AtomTextEdit::insert(TextUnit::from(0), text)])
-                    .boxed(),
-            )
-            .prop_map(TextEdit::from_atoms)
-            .boxed();
-    }
-
-    let offsets = text_offsets(text);
-    let max_cuts = 7.min(offsets.len());
-
-    proptest::sample::subsequence(offsets, 0..max_cuts)
-        .prop_flat_map(|cuts| {
-            let strategies: Vec<_> = cuts
-                .chunks(2)
-                .map(|chunk| match *chunk {
-                    [from, to] => {
-                        let range = TextRange::from_to(from, to);
-                        Just(AtomTextEdit::delete(range))
-                            .boxed()
-                            .prop_union(
-                                arb_text()
-                                    .prop_map(move |text| AtomTextEdit::replace(range, text))
-                                    .boxed(),
-                            )
-                            .boxed()
-                    }
-                    [x] => arb_text().prop_map(move |text| AtomTextEdit::insert(x, text)).boxed(),
-                    _ => unreachable!(),
-                })
-                .collect();
-            strategies
-        })
-        .prop_map(TextEdit::from_atoms)
-        .boxed()
-}
-
-#[derive(Debug, Clone)]
-pub struct ArbTextWithEdit {
-    pub text: String,
-    pub edit: TextEdit,
-}
-
-pub fn arb_text_with_edit() -> BoxedStrategy<ArbTextWithEdit> {
-    let text = arb_text();
-    text.prop_flat_map(|s| {
-        let edit = arb_text_edit(&s);
-        (Just(s), edit)
-    })
-    .prop_map(|(text, edit)| ArbTextWithEdit { text, edit })
-    .boxed()
-}
diff --git a/xtask/tests/tidy-tests/docs.rs b/xtask/tests/tidy-tests/docs.rs
index 6a69e7d6a0..7ae73b9344 100644
--- a/xtask/tests/tidy-tests/docs.rs
+++ b/xtask/tests/tidy-tests/docs.rs
@@ -1,5 +1,6 @@
 use std::{collections::HashMap, fs, io::prelude::*, io::BufReader, path::Path};
 
+use anyhow::Context;
 use walkdir::{DirEntry, WalkDir};
 use xtask::project_root;
 
@@ -50,7 +51,10 @@ fn no_docs_comments() {
         }
         let mut reader = BufReader::new(fs::File::open(f.path()).unwrap());
         let mut line = String::new();
-        reader.read_line(&mut line).unwrap();
+        reader
+            .read_line(&mut line)
+            .with_context(|| format!("Failed to read {}", f.path().display()))
+            .unwrap();
 
         if line.starts_with("//!") {
             if line.contains("FIXME") {