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,refactor

Priority Levels

• :higher

• Critical issues

• :high

• Important issues

• :normal

• Default priority

• :low

• Minor issues

• :ignore

• Completely disabled