Pass check metadata (a JSON string) into the check itself

This is so we can have multiple checks with the same Rust implementation but with slightly different behavior.

Author: simoncozens

fontspector-checkapi/src/check.rs

@@ -42,6 +42,7 @@ pub struct Check<'a> {
     pub fix_source: Option<&'a dyn Fn(&Testable) -> FixFnResult>,
     pub applies_to: &'a str,
     pub flags: CheckFlags,
+    pub _metadata: Option<&'static str>,
 }
 
 // Are we? Really? I don't know. Let's find out...
@@ -62,6 +63,17 @@ impl<'a> Check<'a> {
         }
     }
 
+    /// Get the metadata for this check
+    ///
+    /// Each check definition can declare associated metadata; this is
+    /// interpreted as a JSON string and returned as a serde_json::Value.
+    pub fn metadata(&self) -> serde_json::Value {
+        #[allow(clippy::expect_used)]
+        self._metadata
+            .map(|s| serde_json::from_str(s).unwrap_or_else(|_| panic!("Bad JSON in {}", self.id)))
+            .unwrap_or_default()
+    }
+
     fn clarify_result(
         &'a self,
         fn_result: CheckFnResult,

fontspector-checkapi/src/context.rs

@@ -1,10 +1,13 @@
 use serde_json::{Map, Value};
 
+use crate::Check;
+
 #[derive(Debug, Clone)]
 pub struct Context {
     pub skip_network: bool,
     pub network_timeout: Option<u64>,
     pub configuration: Map<String, Value>,
+    pub check_metadata: Value,
 }
 
 impl Context {
@@ -15,17 +18,18 @@ impl Context {
     /// as the configuration for this check.
     pub fn specialize(
         &self,
-        checkname: &str,
+        check: &Check,
         configuration: &Map<String, serde_json::Value>,
     ) -> Self {
         Context {
             skip_network: self.skip_network,
             network_timeout: self.network_timeout,
             configuration: configuration
-                .get(checkname)
+                .get(check.id)
                 .and_then(|x| x.as_object())
                 .cloned()
                 .unwrap_or_default(),
+            check_metadata: check.metadata(),
         }
     }
 }

fontspector-checkapi/src/profile.rs

@@ -97,15 +97,15 @@ impl Profile {
                     .filter(|checkname| {
                         included_excluded(checkname, include_checks, exclude_checks)
                     })
-                    .map(|checkname| {
-                        (
-                            sectionname.clone(),
-                            registry.checks.get(checkname),
-                            general_context.specialize(checkname, &configuration),
-                        )
-                    })
-                    .flat_map(|(sectionname, check, context)| {
-                        check.map(|c| (sectionname, c, context))
+                    .map(|checkname| (sectionname.clone(), registry.checks.get(checkname)))
+                    .filter_map(|(sectionname, check)| {
+                        check.map(|check| {
+                            (
+                                sectionname,
+                                check,
+                                general_context.specialize(check, &configuration),
+                            )
+                        })
                     })
             })
             .flat_map(|(sectionname, check, context): (String, &Check, Context)| {

fontspector-checkhelper/src/check.rs

@@ -1,7 +1,6 @@
 use std::str::FromStr;
 
-use darling::Error;
-use darling::{ast::NestedMeta, FromMeta};
+use darling::{ast::NestedMeta, Error, FromMeta};
 use proc_macro::TokenStream;
 use proc_macro2::Span;
 use quote::quote;
@@ -47,6 +46,7 @@ struct CheckParams {
     applies_to: Option<String>,
     hotfix: Option<Ident>,
     fix_source: Option<Ident>,
+    metadata: Option<String>,
 }
 
 pub(crate) fn check_impl(args: TokenStream, input: TokenStream) -> TokenStream {
@@ -106,7 +106,10 @@ pub(crate) fn check_impl(args: TokenStream, input: TokenStream) -> TokenStream {
         Implementation::CheckOne => quote!(CheckImplementation::CheckOne(&#impl_ident)),
         Implementation::CheckAll => quote!(CheckImplementation::CheckAll(&#impl_ident)),
     };
-
+    let metadata = match params.metadata {
+        Some(metadata) => quote!(Some(&#metadata)),
+        None => quote!(None),
+    };
     quote!(
         #(#attrs)*
         #vis #new_sig {
@@ -124,6 +127,7 @@ pub(crate) fn check_impl(args: TokenStream, input: TokenStream) -> TokenStream {
             hotfix: #hotfix,
             fix_source: #fix_source,
             flags: CheckFlags::default(),
+            _metadata: #metadata,
         };
     )
     .into()

fontspector-cli/src/main.rs

@@ -130,6 +130,7 @@ fn main() {
             skip_network: args.skip_network,
             network_timeout: Some(10), // XXX
             configuration: Map::new(),
+            check_metadata: serde_json::Value::Null,
         },
         configuration,
         &testables,

fontspector-web/src/lib.rs

@@ -41,6 +41,7 @@ pub fn check_fonts(fonts: &JsValue) -> Result<String, JsValue> {
         skip_network: true,
         network_timeout: None,
         configuration: serde_json::Map::new(),
+        check_metadata: serde_json::Value::Null,
     };
     let all_testables: Vec<TestableType> = collection.collection_and_files().collect();
 

profile-testplugin/src/lib.rs

@@ -32,12 +32,31 @@ fn validate_toml(c: &Testable, _context: &Context) -> CheckFnResult {
     })
 }
 
+#[check(
+    id = "test/test_check_metadata",
+    title = "Check we can pass metadata from the check definition into the check",
+    rationale = "This check is part of the example of how to create plugins.",
+    proposal = "https://github.com/simoncozens/fontspector/commit/5fdf9750991176c8e2776557ce6c17c642c24a73",
+    applies_to = "TTF",
+    metadata = r#"{"foo": "bar"}"#
+)]
+fn check_metadata(_c: &Testable, context: &Context) -> CheckFnResult {
+    if context.check_metadata.get("foo") == Some(&serde_json::Value::String("bar".to_string())) {
+        Ok(Status::just_one_pass())
+    } else {
+        Ok(Status::just_one_fail(
+            "metadata-mismatch",
+            "Metadata mismatch",
+        ))
+    }
+}
+
 impl fontspector_checkapi::Plugin for Test {
     fn register(&self, cr: &mut Registry) -> Result<(), String> {
         let toml = FileType::new("*.toml");
         cr.register_filetype("TOML", toml);
 
-        cr.register_simple_profile("test", vec![validate_toml, say_hello])
+        cr.register_simple_profile("test", vec![validate_toml, say_hello, check_metadata])
     }
 }