Remove testify/require dependency and use standard testing

[kyleconroy]

This PR removes the github.com/stretchr/testify/require dependency from the codebase and replaces all assertion calls with standard Go testing patterns using reflect.DeepEqual() for equality checks and manual t.Fatal() calls for assertions.

Summary

The testify/require library has been completely removed as a dependency. All test files that previously used require.Equal(), require.True(), require.False(), require.NoError(), etc. have been refactored to use idiomatic Go testing with the standard testing package.

Key Changes

• Removed github.com/stretchr/testify v1.8.4 from go.mod
• Replaced all require.Equal(t, expected, actual) calls with reflect.DeepEqual() checks followed by t.Fatalf() on mismatch
• Replaced require.True(t, condition) with if !condition { t.Fatal("expected true") }
• Replaced require.False(t, condition) with if condition { t.Fatal("expected false") }
• Replaced require.NoError(t, err) with if err != nil { t.Fatal(err) }
• Replaced require.NotEmpty(t, value) with if len(value) == 0 { t.Fatal("expected non-empty") }
• Added "reflect" imports to test files where needed
• Reorganized import statements to follow Go conventions (standard library, then external packages)

Files Modified

Test files across multiple packages were updated:

• types/field_type_test.go
• parser/lexer_test.go, parser/digester_test.go, parser/lateral_test.go, parser/reserved_words_test.go, parser/consistent_test.go, parser/hintparser_test.go, parser/keywords_test.go
• ast/util_test.go, ast/stats_test.go, ast/base_test.go, ast/dml_test.go, ast/model_test.go, ast/misc_test.go, ast/functions_test.go, ast/procedure_test.go, ast/flag_test.go, ast/format_test.go, ast/ddl_test.go, ast/expressions_test.go, ast/sem_test.go
• mysql/privs_test.go, mysql/const_test.go, mysql/type_test.go, mysql/error_test.go
• charset/charset_test.go, charset/encoding_test.go
• auth/tidb_sm3_test.go, auth/caching_sha2_test.go, auth/mysql_native_password_test.go
• terror/terror_test.go
• format/format_test.go
• duration/duration_test.go
• util/escape_test.go
• generate_keyword/genkeyword_test.go

Implementation Details

The refactoring maintains the same test logic and assertions while using only the Go standard library. Error messages follow a consistent pattern: "got %v, want %v" for equality assertions and descriptive messages for boolean checks.

https://claude.ai/code/session_01SzZiuen17CDNi8REpAGw1k