Credo Configuration
Credo is a static code analysis tool for Elixir focused on code quality and consistency.
Configuration File
.credo.exs
%{
configs: [
%{
name: "default",
strict: true,
color: true,
files: %{
included: ["lib/", "src/", "test/", "web/", "apps/*/lib/", "apps/*/test/"],
excluded: [~r"/_build/", ~r"/deps/", ~r"/node_modules/"]
},
plugins: [],
requires: [],
parse_timeout: 5000,
checks: %{
enabled: [
# Consistency checks
{Credo.Check.Consistency.ExceptionNames, []},
{Credo.Check.Consistency.LineEndings, []},
{Credo.Check.Consistency.ParameterPatternMatching, []},
{Credo.Check.Consistency.SpaceAroundOperators, []},
{Credo.Check.Consistency.SpaceInParentheses, []},
{Credo.Check.Consistency.TabsOrSpaces, []},
# Design checks
{Credo.Check.Design.AliasUsage, [priority: :low, if_nested_deeper_than: 2]},
{Credo.Check.Design.TagFIXME, []},
{Credo.Check.Design.TagTODO, [exit_status: 0]},
# Readability checks
{Credo.Check.Readability.AliasOrder, []},
{Credo.Check.Readability.FunctionNames, []},
{Credo.Check.Readability.LargeNumbers, []},
{Credo.Check.Readability.MaxLineLength, [priority: :low, max_length: 120]},
{Credo.Check.Readability.ModuleAttributeNames, []},
{Credo.Check.Readability.ModuleDoc, []},
{Credo.Check.Readability.ModuleNames, []},
{Credo.Check.Readability.ParenthesesInCondition, []},
{Credo.Check.Readability.ParenthesesOnZeroArityDefs, []},
{Credo.Check.Readability.PipeIntoAnonymousFunctions, []},
{Credo.Check.Readability.PredicateFunctionNames, []},
{Credo.Check.Readability.PreferImplicitTry, []},
{Credo.Check.Readability.RedundantBlankLines, []},
{Credo.Check.Readability.Semicolons, []},
{Credo.Check.Readability.SpaceAfterCommas, []},
{Credo.Check.Readability.StringSigils, []},
{Credo.Check.Readability.TrailingBlankLine, []},
{Credo.Check.Readability.TrailingWhiteSpace, []},
{Credo.Check.Readability.UnnecessaryAliasExpansion, []},
{Credo.Check.Readability.VariableNames, []},
{Credo.Check.Readability.WithSingleClause, []},
# Refactoring opportunities
{Credo.Check.Refactor.Apply, []},
{Credo.Check.Refactor.CondStatements, []},
{Credo.Check.Refactor.CyclomaticComplexity, [max_complexity: 12]},
{Credo.Check.Refactor.FunctionArity, [max_arity: 8]},
{Credo.Check.Refactor.LongQuoteBlocks, []},
{Credo.Check.Refactor.MatchInCondition, []},
{Credo.Check.Refactor.MapJoin, []},
{Credo.Check.Refactor.NegatedConditionsInUnless, []},
{Credo.Check.Refactor.NegatedConditionsWithElse, []},
{Credo.Check.Refactor.Nesting, [max_nesting: 3]},
{Credo.Check.Refactor.UnlessWithElse, []},
{Credo.Check.Refactor.WithClauses, []},
# Warnings
{Credo.Check.Warning.ApplicationConfigInModuleAttribute, []},
{Credo.Check.Warning.BoolOperationOnSameValues, []},
{Credo.Check.Warning.ExpensiveEmptyEnumCheck, []},
{Credo.Check.Warning.IExPry, []},
{Credo.Check.Warning.IoInspect, []},
{Credo.Check.Warning.OperationOnSameValues, []},
{Credo.Check.Warning.OperationWithConstantResult, []},
{Credo.Check.Warning.RaiseInsideRescue, []},
{Credo.Check.Warning.SpecWithStruct, []},
{Credo.Check.Warning.UnusedEnumOperation, []},
{Credo.Check.Warning.UnusedFileOperation, []},
{Credo.Check.Warning.UnusedKeywordOperation, []},
{Credo.Check.Warning.UnusedListOperation, []},
{Credo.Check.Warning.UnusedPathOperation, []},
{Credo.Check.Warning.UnusedRegexOperation, []},
{Credo.Check.Warning.UnusedStringOperation, []},
{Credo.Check.Warning.UnusedTupleOperation, []},
{Credo.Check.Warning.UnsafeExec, []}
],
disabled: [
# Controversial and experimental checks
{Credo.Check.Consistency.MultiAliasImportRequireUse, []},
{Credo.Check.Consistency.UnusedVariableNames, []},
{Credo.Check.Design.DuplicatedCode, []},
{Credo.Check.Design.SkipTestWithoutComment, []},
{Credo.Check.Readability.AliasAs, []},
{Credo.Check.Readability.BlockPipe, []},
{Credo.Check.Readability.ImplTrue, []},
{Credo.Check.Readability.MultiAlias, []},
{Credo.Check.Readability.NestedFunctionCalls, []},
{Credo.Check.Readability.OneArityFunctionInPipe, []},
{Credo.Check.Readability.OnePipePerLine, []},
{Credo.Check.Readability.SeparateAliasRequire, []},
{Credo.Check.Readability.SingleFunctionToBlockPipe, []},
{Credo.Check.Readability.SinglePipe, []},
{Credo.Check.Readability.Specs, []},
{Credo.Check.Readability.StrictModuleLayout, []},
{Credo.Check.Readability.WithCustomTaggedTuple, []},
{Credo.Check.Refactor.ABCSize, []},
{Credo.Check.Refactor.AppendSingleItem, []},
{Credo.Check.Refactor.DoubleBooleanNegation, []},
{Credo.Check.Refactor.FilterReject, []},
{Credo.Check.Refactor.IoPuts, []},
{Credo.Check.Refactor.MapMap, []},
{Credo.Check.Refactor.ModuleDependencies, []},
{Credo.Check.Refactor.NegatedIsNil, []},
{Credo.Check.Refactor.PipeChainStart, []},
{Credo.Check.Refactor.RejectFilter, []},
{Credo.Check.Refactor.VariableRebinding, []},
{Credo.Check.Warning.LazyLogging, []},
{Credo.Check.Warning.LeakyEnvironment, []},
{Credo.Check.Warning.MapGetUnsafePass, []},
{Credo.Check.Warning.MixEnv, []},
{Credo.Check.Warning.UnsafeToAtom, []}
]
}
}
]
}Multiple Configurations
%{
configs: [
%{
name: "default",
# Default strict config
},
%{
name: "legacy",
files: %{
included: ["lib/legacy/"]
},
checks: %{
disabled: [
{Credo.Check.Readability.ModuleDoc, []}
]
}
}
]
}Command Line Options
# Use specific config
mix credo --config-name legacy
# Strict mode
mix credo --strict
# Show all issues
mix credo --all
# Only specific categories
mix credo --only readability,refactorPriority Levels
:higher- Critical issues:high- Important issues:normal- Default priority:low- Minor issues:ignore- Completely disabled