Auto merge of #53410 - djrenren:custom-test-frameworks, r=<try>

Introduce Custom Test Frameworks

Introduces `#[test_case]` and `#[test_runner]` and re-implements `#[test]` and `#[bench]` in terms of them.

Details found here: https://blog.jrenner.net/rust/testing/2018/08/06/custom-test-framework-prop.html

Author: bors

src/Cargo.lock

@@ -2770,6 +2770,7 @@ name = "syntax_ext"
 version = "0.0.0"
 dependencies = [
  "fmt_macros 0.0.0",
+ "log 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "proc_macro 0.0.0",
  "rustc_data_structures 0.0.0",
  "rustc_errors 0.0.0",

src/librustc_lint/builtin.rs

@@ -1842,43 +1842,56 @@ impl EarlyLintPass for EllipsisInclusiveRangePatterns {
 }
 
 declare_lint! {
-    UNNAMEABLE_TEST_FUNCTIONS,
+    UNNAMEABLE_TEST_ITEMS,
     Warn,
-    "detects an function that cannot be named being marked as #[test]"
+    "detects an item that cannot be named being marked as #[test_case]",
+    report_in_external_macro: true
 }
 
-pub struct UnnameableTestFunctions;
+pub struct UnnameableTestItems {
+    boundary: ast::NodeId, // NodeId of the item under which things are not nameable
+    items_nameable: bool,
+}
+
+impl UnnameableTestItems {
+    pub fn new() -> Self {
+        Self {
+            boundary: ast::DUMMY_NODE_ID,
+            items_nameable: true
+        }
+    }
+}
 
-impl LintPass for UnnameableTestFunctions {
+impl LintPass for UnnameableTestItems {
     fn get_lints(&self) -> LintArray {
-        lint_array!(UNNAMEABLE_TEST_FUNCTIONS)
+        lint_array!(UNNAMEABLE_TEST_ITEMS)
     }
 }
 
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnnameableTestFunctions {
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnnameableTestItems {
     fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
-        match it.node {
-            hir::ItemKind::Fn(..) => {
-                for attr in &it.attrs {
-                    if attr.name() == "test" {
-                        let parent = cx.tcx.hir.get_parent(it.id);
-                        match cx.tcx.hir.find(parent) {
-                            Some(hir_map::NodeItem(hir::Item {node: hir::ItemKind::Mod(_), ..})) |
-                            None => {}
-                            _ => {
-                                cx.struct_span_lint(
-                                    UNNAMEABLE_TEST_FUNCTIONS,
-                                    attr.span,
-                                    "cannot test inner function",
-                                ).emit();
-                            }
-                        }
-                        break;
-                    }
-                }
+        if self.items_nameable {
+            if let hir::ItemKind::Mod(..) = it.node {}
+            else {
+                self.items_nameable = false;
+                self.boundary = it.id;
             }
-            _ => return,
-        };
+            return;
+        }
+
+        if let Some(attr) = attr::find_by_name(&it.attrs, "test_case") {
+            cx.struct_span_lint(
+                UNNAMEABLE_TEST_ITEMS,
+                attr.span,
+                "cannot test inner items",
+            ).emit();
+        }
+    }
+
+    fn check_item_post(&mut self, _cx: &LateContext, it: &hir::Item) {
+        if !self.items_nameable && self.boundary == it.id {
+            self.items_nameable = true;
+        }
     }
 }
 

src/librustc_lint/lib.rs

@@ -148,7 +148,7 @@ pub fn register_builtins(store: &mut lint::LintStore, sess: Option<&Session>) {
         MutableTransmutes: MutableTransmutes,
         UnionsWithDropFields: UnionsWithDropFields,
         UnreachablePub: UnreachablePub,
-        UnnameableTestFunctions: UnnameableTestFunctions,
+        UnnameableTestItems: UnnameableTestItems::new(),
         TypeAliasBounds: TypeAliasBounds,
         UnusedBrokenConst: UnusedBrokenConst,
         TrivialConstraints: TrivialConstraints,

src/librustc_resolve/macros.rs

@@ -475,6 +475,10 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
             return def;
         }
 
+        if kind == MacroKind::Attr && *&path[0].as_str() == "test" {
+            return Ok(self.macro_prelude.get(&path[0].name).unwrap().def())
+        }
+
         let legacy_resolution = self.resolve_legacy_scope(&invocation.legacy_scope, path[0], false);
         let result = if let Some((legacy_binding, _)) = legacy_resolution {
             Ok(legacy_binding.def())

src/libsyntax/ast.rs

@@ -1582,7 +1582,7 @@ impl TyKind {
         if let TyKind::ImplicitSelf = *self { true } else { false }
     }
 
-    crate fn is_unit(&self) -> bool {
+    pub fn is_unit(&self) -> bool {
         if let TyKind::Tup(ref tys) = *self { tys.is_empty() } else { false }
     }
 }

src/libsyntax/config.rs

@@ -119,7 +119,7 @@ impl<'a> StripUnconfigured<'a> {
     pub fn in_cfg(&mut self, attrs: &[ast::Attribute]) -> bool {
         attrs.iter().all(|attr| {
             // When not compiling with --test we should not compile the #[test] functions
-            if !self.should_test && is_test_or_bench(attr) {
+            if !self.should_test && is_test(attr) {
                 return false;
             }
 
@@ -249,7 +249,7 @@ impl<'a> StripUnconfigured<'a> {
         //
         // NB: This is intentionally not part of the fold_expr() function
         //     in order for fold_opt_expr() to be able to avoid this check
-        if let Some(attr) = expr.attrs().iter().find(|a| is_cfg(a) || is_test_or_bench(a)) {
+        if let Some(attr) = expr.attrs().iter().find(|a| is_cfg(a) || is_test(a)) {
             let msg = "removing an expression is not supported in this position";
             self.sess.span_diagnostic.span_err(attr.span, msg);
         }
@@ -353,6 +353,6 @@ fn is_cfg(attr: &ast::Attribute) -> bool {
     attr.check_name("cfg")
 }
 
-pub fn is_test_or_bench(attr: &ast::Attribute) -> bool {
-    attr.check_name("test") || attr.check_name("bench")
+pub fn is_test(att: &ast::Attribute) -> bool {
+    att.check_name("test_case")
 }

src/libsyntax/ext/expand.rs

@@ -12,10 +12,9 @@ use ast::{self, Block, Ident, NodeId, PatKind, Path};
 use ast::{MacStmtStyle, StmtKind, ItemKind};
 use attr::{self, HasAttrs};
 use source_map::{ExpnInfo, MacroBang, MacroAttribute, dummy_spanned, respan};
-use config::{is_test_or_bench, StripUnconfigured};
+use config::StripUnconfigured;
 use errors::{Applicability, FatalError};
 use ext::base::*;
-use ext::build::AstBuilder;
 use ext::derive::{add_derived_markers, collect_derives};
 use ext::hygiene::{self, Mark, SyntaxContext};
 use ext::placeholders::{placeholder, PlaceholderExpander};
@@ -1370,51 +1369,25 @@ impl<'a, 'b> Folder for InvocationCollector<'a, 'b> {
                 self.cx.current_expansion.directory_ownership = orig_directory_ownership;
                 result
             }
-            // Ensure that test functions are accessible from the test harness.
+
+            // Ensure that test items can be exported by the harness generator.
             // #[test] fn foo() {}
             // becomes:
             // #[test] pub fn foo_gensym(){}
-            // #[allow(unused)]
-            // use foo_gensym as foo;
-            ast::ItemKind::Fn(..) if self.cx.ecfg.should_test => {
-                if self.tests_nameable && item.attrs.iter().any(|attr| is_test_or_bench(attr)) {
-                    let orig_ident = item.ident;
-                    let orig_vis   = item.vis.clone();
-
+              ast::ItemKind::Const(..)
+            | ast::ItemKind::Static(..)
+            | ast::ItemKind::Fn(..) if self.cx.ecfg.should_test => {
+                if self.tests_nameable && attr::contains_name(&item.attrs, "test_case") {
                     // Publicize the item under gensymed name to avoid pollution
+                    // This means #[test_case] items can't be referenced by user code
                     item = item.map(|mut item| {
                         item.vis = respan(item.vis.span, ast::VisibilityKind::Public);
                         item.ident = item.ident.gensym();
                         item
                     });
-
-                    // Use the gensymed name under the item's original visibility
-                    let mut use_item = self.cx.item_use_simple_(
-                        item.ident.span,
-                        orig_vis,
-                        Some(orig_ident),
-                        self.cx.path(item.ident.span,
-                            vec![keywords::SelfValue.ident(), item.ident]));
-
-                    // #[allow(unused)] because the test function probably isn't being referenced
-                    use_item = use_item.map(|mut ui| {
-                        ui.attrs.push(
-                            self.cx.attribute(DUMMY_SP, attr::mk_list_item(DUMMY_SP,
-                                Ident::from_str("allow"), vec![
-                                    attr::mk_nested_word_item(Ident::from_str("unused"))
-                                ]
-                            ))
-                        );
-
-                        ui
-                    });
-
-                    OneVector::many(
-                        self.fold_unnameable(item).into_iter()
-                            .chain(self.fold_unnameable(use_item)))
-                } else {
-                    self.fold_unnameable(item)
                 }
+
+                self.fold_unnameable(item)
             }
             _ => self.fold_unnameable(item),
         }

src/libsyntax/feature_gate.rs

@@ -503,6 +503,10 @@ declare_features! (
 
     // unsized rvalues at arguments and parameters
     (active, unsized_locals, "1.30.0", Some(48055), None),
+
+    // #![test_runner]
+    // #[test_case]
+    (active, custom_test_frameworks, "1.30.0", Some(50297), None),
 );
 
 declare_features! (
@@ -757,6 +761,10 @@ pub const BUILTIN_ATTRIBUTES: &'static [(&'static str, AttributeType, AttributeG
     ("no_link", Normal, Ungated),
     ("derive", Normal, Ungated),
     ("should_panic", Normal, Ungated),
+    ("test_case", Normal, Gated(Stability::Unstable,
+                                "custom_test_frameworks",
+                                "Custom test frameworks are experimental",
+                                cfg_fn!(custom_test_frameworks))),
     ("ignore", Normal, Ungated),
     ("no_implicit_prelude", Normal, Ungated),
     ("reexport_test_harness_main", Normal, Ungated),
@@ -1123,6 +1131,10 @@ pub const BUILTIN_ATTRIBUTES: &'static [(&'static str, AttributeType, AttributeG
     ("no_builtins", CrateLevel, Ungated),
     ("recursion_limit", CrateLevel, Ungated),
     ("type_length_limit", CrateLevel, Ungated),
+    ("test_runner", CrateLevel, Gated(Stability::Unstable,
+                    "custom_test_frameworks",
+                    "Custom Test Frameworks is an unstable feature",
+                    cfg_fn!(custom_test_frameworks))),
 ];
 
 // cfg(...)'s that are feature gated