Add a fuzzing subcommand

.cargo/config

@@ -1,10 +1,16 @@
 [alias]
 # Automatically generates the ast and syntax kinds files
 gen-syntax   = "run --package tools --bin tools -- gen-syntax"
+# Extracts the tests from 
 gen-tests    = "run --package tools --bin tools -- gen-tests"
+# Installs the visual studio code extension
 install-code = "run --package tools --bin tools -- install-code"
+# Formats the full repository or installs the git hook to do it automatically.
 format       = "run --package tools --bin tools -- format"
 format-hook  = "run --package tools --bin tools -- format-hook"
+# Runs the fuzzing test suite (currently only parser)
+fuzz-tests   = "run --package tools --bin tools -- fuzz-tests"
 
 render-test  = "run --package ra_cli -- render-test"
+# Parse a file. This should be piped the file contents
 parse        = "run --package ra_cli -- parse"

crates/tools/src/lib.rs

@@ -139,3 +139,20 @@ pub fn install_format_hook() -> Result<()> {
     }
     Ok(())
 }
+
+pub fn run_fuzzer() -> Result<()> {
+    match Command::new("cargo")
+        .args(&["fuzz", "--help"])
+        .stderr(Stdio::null())
+        .stdout(Stdio::null())
+        .status()
+    {
+        Ok(status) if status.success() => (),
+        _ => run("cargo install cargo-fuzz", ".")?,
+    };
+
+    run(
+        "rustup run nightly -- cargo fuzz run parser",
+        "./crates/ra_syntax",
+    )
+}

crates/tools/src/main.rs

@@ -7,7 +7,10 @@ use std::{
 use clap::{App, Arg, SubCommand};
 use failure::bail;
 
-use tools::{collect_tests, generate, install_format_hook, run, run_rustfmt, Mode, Overwrite, Result, Test, Verify, project_root};
+use tools::{
+    collect_tests, generate,install_format_hook, run, run_rustfmt,
+    Mode, Overwrite, Result, Test, Verify, project_root, run_fuzzer
+};
 
 const GRAMMAR_DIR: &str = "crates/ra_syntax/src/grammar";
 const OK_INLINE_TESTS_DIR: &str = "crates/ra_syntax/tests/data/parser/inline/ok";
@@ -27,6 +30,7 @@ fn main() -> Result<()> {
         .subcommand(SubCommand::with_name("install-code"))
         .subcommand(SubCommand::with_name("format"))
         .subcommand(SubCommand::with_name("format-hook"))
+        .subcommand(SubCommand::with_name("fuzz-tests"))
         .get_matches();
     let mode = if matches.is_present("verify") {
         Verify
@@ -42,6 +46,7 @@ fn main() -> Result<()> {
         "gen-syntax" => generate(Overwrite)?,
         "format" => run_rustfmt(mode)?,
         "format-hook" => install_format_hook()?,
+        "fuzz-tests" => run_fuzzer()?,
         _ => unreachable!(),
     }
     Ok(())