Improvements to code coverage:

More tests and test cases are added to bring up
the percentage of library code covered by tests.

test/http/parse_error.cpp

@@ -7,3 +7,50 @@
 
 // Test that header file is self-contained.
 #include <beast/http/parse_error.hpp>
+
+#include <beast/unit_test/suite.hpp>
+#include <memory>
+
+namespace beast {
+namespace http {
+
+class parse_error_test : public unit_test::suite
+{
+public:
+    void check(char const* name, parse_error ev)
+    {
+        auto const ec = make_error_code(ev);
+        expect(std::string{ec.category().name()} == name);
+        expect(! ec.message().empty());
+        expect(std::addressof(ec.category()) ==
+            std::addressof(get_parse_error_category()));
+        expect(get_parse_error_category().equivalent(static_cast<int>(ev),
+            ec.category().default_error_condition(static_cast<int>(ev))));
+        expect(get_parse_error_category().equivalent(
+            ec, static_cast<int>(ev)));
+    }
+
+    void run() override
+    {
+        check("http", parse_error::connection_closed);
+        check("http", parse_error::bad_method);
+        check("http", parse_error::bad_uri);
+        check("http", parse_error::bad_version);
+        check("http", parse_error::bad_crlf);
+        check("http", parse_error::bad_request);
+        check("http", parse_error::bad_status_code);
+        check("http", parse_error::bad_status);
+        check("http", parse_error::bad_field);
+        check("http", parse_error::bad_value);
+        check("http", parse_error::bad_content_length);
+        check("http", parse_error::illegal_content_length);
+        check("http", parse_error::bad_on_headers_rv);
+        check("http", parse_error::invalid_chunk_size);
+        check("http", parse_error::short_read);
+    }
+};
+
+BEAST_DEFINE_TESTSUITE(parse_error,http,beast);
+
+} // http
+} // beast