Slightly improve error reporting

Reviewed By: AndreasBackx

Differential Revision: D64753922

fbshipit-source-id: da331d0b06fdae1943ee4f219fd06c90a443c655

Author: abesto

Cargo.toml

@@ -66,6 +66,7 @@ shell-escape = "0.1"
 strip-ansi-escapes = "0.1"
 subprocess = "0.2.7"
 tempfile = "3.8"
+thiserror = "1.0"
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
 unicode_categories = "0.1"

selftest/complex/missing-language/missing-language.md

@@ -2,22 +2,20 @@
 
 ```scrut
 $ $SCRUT_BIN test --match-markdown "*.mdtest" "$TESTDIR"/missing-language.mdtest 2>&1
-* parse test from "*missing-language.mdtest" with markdown parser (glob)
+* Failed to parse test from "*missing-language.mdtest" with markdown parser (glob)
 
 Caused by:
     Code block starting at line 2 is missing language specifier. Use ```scrut to make this block a Scrut test, or any other language to make Scrut skip this block.
-* (glob?)
 [1]
 ```
 
 # Error on EMPTY code block with no language specified
 
 ```scrut
 $ $SCRUT_BIN test --match-markdown "*.mdtest" "$TESTDIR"/missing-language-empty-block.mdtest 2>&1
-* parse test from "*missing-language-empty-block.mdtest" with markdown parser (glob)
+* Failed to parse test from "*missing-language-empty-block.mdtest" with markdown parser (glob)
 
 Caused by:
     Code block starting at line 2 is missing language specifier. Use ```scrut to make this block a Scrut test, or any other language to make Scrut skip this block.
-* (glob?)
 [1]
 ```

src/bin/commands/test.rs

@@ -6,7 +6,6 @@
  */
 
 use std::collections::BTreeMap;
-use std::fmt::Display;
 use std::io::stdout;
 use std::io::IsTerminal;
 use std::path::Path;
@@ -47,15 +46,10 @@ use crate::utils::make_executor;
 use crate::utils::FileParser;
 use crate::utils::TestEnvironment;
 
-#[derive(Debug, Clone)]
+#[derive(Debug, thiserror::Error)]
+#[error("validation failed")]
 pub struct ValidationFailedError;
 
-impl Display for ValidationFailedError {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "validation failed")
-    }
-}
-
 /// Run tests from files or directories
 #[derive(Debug, ClapParser)]
 pub struct Args {

src/bin/fb_main.rs

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+extern crate scrut;
+
+mod commands;
+mod fb_main_common;
+mod utils;
+
+use anyhow::Result;
+use cli::ExitCode;
+use fb_main_common::main_impl;
+use fb_main_common::Args;
+use fbinit::FacebookInit;
+
+#[cli::main("scrut", error_logging)]
+pub fn main(fb: FacebookInit, args: Args) -> Result<ExitCode> {
+    main_impl(fb, args)
+}

src/bin/fb_main_common.rs

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+use anyhow::anyhow;
+use anyhow::Result;
+use clap::Parser;
+use cli::ExitCode;
+use fbinit::FacebookInit;
+use scrut::parsers::markdown::MarkdownParserError;
+use tracing::error;
+
+use crate::commands::root::Commands;
+use crate::commands::root::GlobalParameters;
+use crate::commands::test::ValidationFailedError;
+
+#[derive(Debug, Parser)]
+#[clap(
+    about = "A testing toolkit to scrutinize CLI applications",
+    author = "clifoundation"
+)]
+pub struct Args {
+    #[clap(subcommand)]
+    commands: Commands,
+
+    #[clap(flatten)]
+    global: GlobalParameters,
+}
+
+/// Implemented here because it's only used in `fb-main*.rs`, and so
+/// there's little point in exposing it to the OSS version.
+pub fn is_user_error(err: &anyhow::Error) -> bool {
+    if let Some(MarkdownParserError::MissingLanguageSpecifier { .. }) =
+        err.downcast_ref::<MarkdownParserError>()
+    {
+        return true;
+    }
+    false
+}
+
+pub fn main_impl(_fb: FacebookInit, args: Args) -> Result<ExitCode> {
+    if let Err(err) = args.commands.run() {
+        if err.downcast_ref::<ValidationFailedError>().is_some() {
+            return Ok(ExitCode::from(50));
+        }
+        if is_user_error(&err) {
+            error!("{:?}", err);
+            Ok(ExitCode::from(1))
+        } else {
+            Err(anyhow!(err))
+        }
+    } else {
+        Ok(ExitCode::SUCCESS)
+    }
+}

src/bin/fb_main_nodeps.rs

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+extern crate scrut;
+
+mod commands;
+mod fb_main_common;
+mod utils;
+
+use anyhow::Result;
+use cli::ExitCode;
+use fb_main_common::main_impl;
+use fb_main_common::Args;
+use fbinit::FacebookInit;
+
+#[cli::main("scrut", usage_logging = false)]
+pub fn main(fb: FacebookInit, args: Args) -> Result<ExitCode> {
+    main_impl(fb, args)
+}

src/bin/utils/file_parser.rs

@@ -72,7 +72,7 @@ impl<'a> FileParser<'a> {
             let (parser_type, parser) = self.parser(&test_file_path, cram_compat)?;
             let (config, testcases) = parser.parse(&test_file_content).with_context(|| {
                 format!(
-                    "parse {} from {:?} with {} parser",
+                    "Failed to parse {} from {:?} with {} parser",
                     name, &test_file_path, parser_type
                 )
             })?;

src/parsers/markdown.rs

@@ -30,6 +30,14 @@ lazy_static! {
 
 pub const DEFAULT_MARKDOWN_LANGUAGES: &[&str] = &["scrut"];
 
+#[derive(Debug, thiserror::Error)]
+pub enum MarkdownParserError {
+    #[error(
+        "Code block starting at line {line} is missing language specifier. Use ```scrut to make this block a Scrut test, or any other language to make Scrut skip this block."
+    )]
+    MissingLanguageSpecifier { line: usize },
+}
+
 /// A parser for Cram `.t` files, which reads [`crate::testcase::TestCase`]s
 /// that are encoded in the form:
 ///
@@ -102,10 +110,9 @@ impl Parser for MarkdownParser {
                     lines: _,
                 } => {
                     if language.is_empty() {
-                        anyhow::bail!(
-                            "Code block starting at line {} is missing language specifier. Use ```scrut to make this block a Scrut test, or any other language to make Scrut skip this block.",
-                            starting_line_number
-                        );
+                        anyhow::bail!(MarkdownParserError::MissingLanguageSpecifier {
+                            line: starting_line_number,
+                        });
                     }
                 }
                 MarkdownToken::TestCodeBlock {