feat(test): improve message for diag assertion failures

Before:

    test/test-parse-typescript-class.cpp:86: Failure
    Value of: diagnostics
    Expected:
      Actual: 24-byte object <A8-6B 7F-6F 01-00 00-00 10-38 01-34 01-00 00-00 10-38 01-34 01-00 00-00>, whose element #0 doesn't match, whose .token (14-15) doesn't equal 13-14

After:

    test/test-parse-typescript-class.cpp:86: Failure
    Value of: diagnostics
    Expected: 1 diagnostic: {
      Diag_Unexpected_Token{.token = 13..14},
    }
      Actual: 1 diagnostic: {
      Diag_Unexpected_Token,
    }, whose element #0 doesn't match, whose .token (14-15) doesn't equal 13-14

src/CMakeLists.txt

@@ -530,6 +530,7 @@ quick_lint_js_add_library(
   quick-lint-js/container/padded-string-debug.cpp
   quick-lint-js/container/vector-profiler-debug.cpp
   quick-lint-js/diag/diag-debug.cpp
+  quick-lint-js/diag/diag-list-debug.cpp
   quick-lint-js/fe/language-debug.cpp
   quick-lint-js/fe/lex-debug.cpp
   quick-lint-js/i18n/po-parser-debug.cpp

src/quick-lint-js/diag/diag-list-debug.cpp

@@ -0,0 +1,40 @@
+// Copyright (C) 2020  Matthew "strager" Glazar
+// See end of file for extended copyright information.
+
+#include <ostream>
+#include <quick-lint-js/diag/diag-list.h>
+
+namespace quick_lint_js {
+std::ostream& operator<<(std::ostream& out, const Diag_List& diags) {
+  int diag_count = 0;
+  diags.for_each([&](Diag_Type, const void*) -> void { diag_count += 1; });
+  out << diag_count << " " << (diag_count == 1 ? "diagnostic" : "diagnostics");
+  if (diag_count > 0) {
+    out << ": {\n";
+    diags.for_each([&](Diag_Type type, const void*) -> void {
+      out << "  " << type << ",\n";
+    });
+    out << "}";
+  }
+  return out;
+}
+
+}
+
+// quick-lint-js finds bugs in JavaScript programs.
+// Copyright (C) 2020  Matthew "strager" Glazar
+//
+// This file is part of quick-lint-js.
+//
+// quick-lint-js is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// quick-lint-js is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with quick-lint-js.  If not, see <https://www.gnu.org/licenses/>.

src/quick-lint-js/diag/diag-list.h

@@ -3,6 +3,7 @@
 
 #pragma once
 
+#include <iosfwd>
 #include <quick-lint-js/diag/diagnostic-types.h>
 #include <quick-lint-js/port/memory-resource.h>
 
@@ -80,6 +81,8 @@ class Diag_List {
 
   friend class Diag_List_Diag_Reporter;
 };
+
+std::ostream &operator<<(std::ostream &, const Diag_List &);
 }
 
 // quick-lint-js finds bugs in JavaScript programs.

test/quick-lint-js/diag-matcher.cpp

@@ -81,17 +81,23 @@ class Diag_Fields_Matcher_Impl_Base
   explicit Diag_Fields_Matcher_Impl_Base(State s) : state_(std::move(s)) {}
 
   void DescribeTo(std::ostream *out) const final {
-    *out << "has type " << this->state_.type;
-    this->describe_fields_to(out);
-  }
+    *out << this->state_.type << "{";
 
-  void DescribeNegationTo(std::ostream *out) const final {
-    *out << "doesn't have type " << this->state_.type;
-    this->describe_fields_to(out);
+    bool is_first_field = true;
+    for (const Field &f : this->state_.fields) {
+      if (!is_first_field) {
+        *out << ", ";
+      }
+      this->describe_field(f, out);
+      is_first_field = false;
+    }
+
+    *out << "}";
   }
 
-  void describe_fields_to(std::ostream *) const {
-    // TODO(strager)
+  void DescribeNegationTo(std::ostream *out) const final {
+    *out << "not ";
+    this->DescribeTo(out);
   }
 
   bool MatchAndExplain(const Diag_Collector::Diag &error,
@@ -127,6 +133,7 @@ class Diag_Fields_Matcher_Impl_Base
   }
 
  protected:
+  virtual void describe_field(const Field &, std::ostream *out) const = 0;
   virtual bool field_matches(const Any_Diag_Pointer &error, const Field &f,
                              testing::MatchResultListener *listener) const = 0;
 
@@ -147,6 +154,48 @@ class Diag_Matcher_2::Impl final
   using Base::Diag_Fields_Matcher_Impl_Base;
 
  protected:
+  void describe_field(const Field &f, std::ostream *out) const override {
+    *out << "." << f.arg.member_name << " = ";
+    switch (f.arg.member_type) {
+    case Diagnostic_Arg_Type::source_code_span:
+      *out << f.begin_offset << ".." << f.end_offset;
+      break;
+
+    case Diagnostic_Arg_Type::char8:
+      *out << "'";
+      // TODO(strager): Escape characters like ' and \ and (null) and (tab).
+      *out << static_cast<char>(f.character);
+      *out << "'";
+      break;
+
+    case Diagnostic_Arg_Type::string8_view:
+      *out << "\"";
+      // TODO(strager): Escape characters like ' and \ and (null) and (tab).
+      *out << out_string8(f.string);
+      *out << "\"";
+      break;
+
+    case Diagnostic_Arg_Type::enum_kind:
+      *out << "Enum_Kind::";
+      *out << f.enum_kind;
+      break;
+
+    case Diagnostic_Arg_Type::statement_kind:
+      *out << "Statement_Kind::";
+      *out << f.statement_kind;
+      break;
+
+    case Diagnostic_Arg_Type::variable_kind:
+      *out << "Variable_Kind::";
+      *out << f.variable_kind;
+      break;
+
+    case Diagnostic_Arg_Type::invalid:
+      QLJS_UNREACHABLE();
+      break;
+    }
+  }
+
   bool field_matches(const Any_Diag_Pointer &error, const Field &f,
                      testing::MatchResultListener *listener) const override {
     switch (f.arg.member_type) {

test/quick-lint-js/diag-matcher.h

@@ -94,6 +94,10 @@ class Diag_Matcher_2 {
   /*implicit*/ operator testing::Matcher<const Diag_Collector::Diag &>() const;
   /*implicit*/ operator testing::Matcher<const Any_Diag_Pointer &>() const;
 
+  void DescribeTo(std::ostream *out) const {
+    return ::testing::Matcher<const Any_Diag_Pointer &>(*this).DescribeTo(out);
+  }
+
  private:
   class Impl;
 

test/quick-lint-js/diagnostic-assertion.cpp

@@ -566,10 +566,17 @@ class Diag_List_Matcher_Impl
       : error_matchers_(std::move(error_matchers)) {}
 
   void DescribeTo([[maybe_unused]] std::ostream* out) const override {
-    // FIXME(strager): Do we need to write anything here?
-  }
-
-  void DescribeNegationTo([[maybe_unused]] std::ostream* out) const override {
+    *out << this->error_matchers_.size() << " "
+         << (this->error_matchers_.size() == 1 ? "diagnostic" : "diagnostics");
+    if (!this->error_matchers_.empty()) {
+      *out << ": {\n";
+      for (const Diag_Matcher_2& matcher : this->error_matchers_) {
+        *out << "  ";
+        matcher.DescribeTo(out);
+        *out << ",\n";
+      }
+      *out << "}";
+    }
     // FIXME(strager): Do we need to write anything here?
   }
 

test/quick-lint-js/gtest.h

@@ -40,6 +40,13 @@ inline void PrintTo(const std::basic_string_view<char8_t> &s,
 }
 #endif
 
+template <class Value>
+std::string get_matcher_description(::testing::Matcher<const Value &> matcher) {
+  std::ostringstream ss;
+  matcher.DescribeTo(&ss);
+  return ss.str();
+}
+
 template <class Value>
 std::string get_matcher_message(::testing::Matcher<const Value &> matcher,
                                 const Value &value) {

test/test-diag-list.cpp

@@ -176,6 +176,20 @@ TEST(Test_Diag_List, clear_removes_old_diagnostics) {
   });
   EXPECT_EQ(count, 1);
 }
+
+TEST(Test_Diag_List, pretty_print_one_diag) {
+  // TODO(strager): Include location information.
+
+  Linked_Bump_Allocator memory("test");
+  {
+    Diag_List diags(&memory);
+    Padded_String code(u8"hello"_sv);
+    diags.add(Diag_Let_With_No_Bindings{.where = span_of(code)});
+    std::ostringstream ss;
+    ss << diags;
+    EXPECT_EQ(ss.str(), "1 diagnostic: {\n  Diag_Let_With_No_Bindings,\n}");
+  }
+}
 }
 }
 

test/test-diagnostic-assertion.cpp

@@ -846,6 +846,10 @@ TEST_F(Test_Diagnostic_Assertion_2, match_offsets_of_1_field_message) {
     EXPECT_EQ(get_matcher_message(matcher, diags),
               "whose element #0 doesn't match, whose .continue_statement (1-4) "
               "doesn't equal 0-5");
+    EXPECT_EQ(get_matcher_description(matcher),
+              "1 diagnostic: {\n  "
+              "Diag_Invalid_Continue{.continue_statement = 0..5},\n"
+              "}");
   }
 
   {
@@ -858,6 +862,10 @@ TEST_F(Test_Diagnostic_Assertion_2, match_offsets_of_1_field_message) {
     EXPECT_EQ(get_matcher_message(matcher, diags),
               "whose element #0 doesn't match, whose .break_statement (1-4) "
               "doesn't equal 0-5");
+    EXPECT_EQ(get_matcher_description(matcher),
+              "1 diagnostic: {\n  "
+              "Diag_Invalid_Break{.break_statement = 0..5},\n"
+              "}");
   }
 }
 
@@ -900,6 +908,11 @@ TEST_F(Test_Diagnostic_Assertion_2, char8_message) {
   EXPECT_EQ(get_matcher_message(matcher, diags),
             "whose element #0 doesn't match, whose .where (0-1) equals 0-1 and "
             "whose .token ('(') doesn't equal ')'");
+  EXPECT_EQ(get_matcher_description(matcher),
+            "1 diagnostic: {\n"
+            "  Diag_Expected_Parenthesis_Around_Do_While_Condition"
+            "{.where = 0..1, .token = ')'},\n"
+            "}");
 }
 
 TEST_F(Test_Diagnostic_Assertion_2, match_span_and_string8_view) {
@@ -942,6 +955,50 @@ TEST_F(Test_Diagnostic_Assertion_2, string8_view_message) {
       get_matcher_message(matcher, diags),
       "whose element #0 doesn't match, whose .characters (0-1) equals 0-1 and "
       "whose .rounded_val (\"HELLO\") doesn't equal \"hello\"");
+  EXPECT_EQ(get_matcher_description(matcher),
+            "1 diagnostic: {\n"
+            "  Diag_Integer_Literal_Will_Lose_Precision"
+            "{.characters = 0..1, .rounded_val = \"hello\"},\n"
+            "}");
+}
+
+TEST_F(Test_Diagnostic_Assertion_2, enum_kind_message) {
+  Padded_String code(u8"hi"_sv);
+  ::testing::Matcher matcher = diagnostics_matcher_2(
+      &code, {u8"^ Diag_TypeScript_Enum_Value_Must_Be_Constant.expression"_diag
+              u8"{.declared_enum_kind=Enum_Kind::declare_const_enum}"_diag});
+  EXPECT_EQ(get_matcher_description(matcher),
+            "1 diagnostic: {\n"
+            "  Diag_TypeScript_Enum_Value_Must_Be_Constant"
+            "{.expression = 0..1, "
+            ".declared_enum_kind = Enum_Kind::declare_const_enum},\n"
+            "}");
+}
+
+TEST_F(Test_Diagnostic_Assertion_2, statement_kind_message) {
+  Padded_String code(u8"hi"_sv);
+  ::testing::Matcher matcher = diagnostics_matcher_2(
+      &code, {u8"^ Diag_Class_Statement_Not_Allowed_In_Body.expected_body"_diag
+              u8"{.kind_of_statement=Statement_Kind::do_while_loop}"_diag});
+  EXPECT_EQ(get_matcher_description(matcher),
+            "1 diagnostic: {\n  "
+            "Diag_Class_Statement_Not_Allowed_In_Body"
+            "{.expected_body = 0..1, "
+            ".kind_of_statement = Statement_Kind::do_while_loop},\n"
+            "}");
+}
+
+TEST_F(Test_Diagnostic_Assertion_2, variable_kind_message) {
+  Padded_String code(u8"hi"_sv);
+  ::testing::Matcher matcher = diagnostics_matcher_2(
+      &code, {u8"^ Diag_Assignment_To_Const_Variable.declaration"_diag
+              u8"{.var_kind=Variable_Kind::_const}"_diag});
+  EXPECT_EQ(get_matcher_description(matcher),
+            "1 diagnostic: {\n"
+            "  Diag_Assignment_To_Const_Variable"
+            "{.declaration = 0..1, "
+            ".var_kind = Variable_Kind::_const},\n"
+            "}");
 }
 
 TEST_F(Test_Diagnostic_Assertion_2,