From 505a2d0bd676c74d9b7723b6ce957f120524dca2 Mon Sep 17 00:00:00 2001 From: Willem van den Ende Date: Fri, 20 Mar 2026 21:17:42 +0000 Subject: [PATCH] Add custom Credo check for conn shadowing in tests Detects `conn = get(conn, ...)` patterns and directs to refactor_conn_aliasing.sh for automatic fixing. --- app/.credo.exs | 226 +++++++++++++++++++ app/lib/firehose/checks/no_conn_shadowing.ex | 44 ++++ 2 files changed, 270 insertions(+) create mode 100644 app/.credo.exs create mode 100644 app/lib/firehose/checks/no_conn_shadowing.ex diff --git a/app/.credo.exs b/app/.credo.exs new file mode 100644 index 0000000..5638a4b --- /dev/null +++ b/app/.credo.exs @@ -0,0 +1,226 @@ +# This file contains the configuration for Credo and you are probably reading +# this after creating it with `mix credo.gen.config`. +# +# If you find anything wrong or unclear in this file, please report an +# issue on GitHub: https://github.com/rrrene/credo/issues +# +%{ + # + # You can have as many configs as you like in the `configs:` field. + configs: [ + %{ + # + # Run any config using `mix credo -C `. If no config name is given + # "default" is used. + # + name: "default", + # + # These are the files included in the analysis: + files: %{ + # + # You can give explicit globs or simply directories. + # In the latter case `**/*.{ex,exs}` will be used. + # + included: [ + "lib/", + "src/", + "test/", + "web/", + "apps/*/lib/", + "apps/*/src/", + "apps/*/test/", + "apps/*/web/" + ], + excluded: [~r"/_build/", ~r"/deps/", ~r"/node_modules/"] + }, + # + # Load and configure plugins here: + # + plugins: [], + # + # If you create your own checks, you must specify the source files for + # them here, so they can be loaded by Credo before running the analysis. + # + requires: ["lib/firehose/checks/"], + # + # If you want to enforce a style guide and need a more traditional linting + # experience, you can change `strict` to `true` below: + # + strict: false, + # + # To modify the timeout for parsing files, change this value: + # + parse_timeout: 5000, + # + # If you want to use uncolored output by default, you can change `color` + # to `false` below: + # + color: true, + # + # You can customize the parameters of any check by adding a second element + # to the tuple. + # + # To disable a check put `false` as second element: + # + # {Credo.Check.Design.DuplicatedCode, false} + # + 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 + # + # You can customize the priority of any check + # Priority values are: `low, normal, high, higher` + # + {Credo.Check.Design.AliasUsage, + [priority: :low, if_nested_deeper_than: 2, if_called_more_often_than: 0]}, + {Credo.Check.Design.TagFIXME, []}, + # You can also customize the exit_status of each check. + # If you don't want TODO comments to cause `mix credo` to fail, just + # set this value to 0 (zero). + # + {Credo.Check.Design.TagTODO, [exit_status: 2]}, + + # + ## 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, []}, + {Credo.Check.Refactor.FilterCount, []}, + {Credo.Check.Refactor.FilterFilter, []}, + {Credo.Check.Refactor.FunctionArity, []}, + {Credo.Check.Refactor.LongQuoteBlocks, []}, + {Credo.Check.Refactor.MapJoin, []}, + {Credo.Check.Refactor.MatchInCondition, []}, + {Credo.Check.Refactor.NegatedConditionsInUnless, []}, + {Credo.Check.Refactor.NegatedConditionsWithElse, []}, + {Credo.Check.Refactor.Nesting, []}, + {Credo.Check.Refactor.RedundantWithClauseResult, []}, + {Credo.Check.Refactor.RejectReject, []}, + {Credo.Check.Refactor.UnlessWithElse, []}, + {Credo.Check.Refactor.WithClauses, []}, + + # + ## Warnings + # + {Credo.Check.Warning.ApplicationConfigInModuleAttribute, []}, + {Credo.Check.Warning.BoolOperationOnSameValues, []}, + {Credo.Check.Warning.Dbg, []}, + {Credo.Check.Warning.ExpensiveEmptyEnumCheck, []}, + {Credo.Check.Warning.IExPry, []}, + {Credo.Check.Warning.IoInspect, []}, + {Credo.Check.Warning.MissedMetadataKeyInLoggerConfig, []}, + {Credo.Check.Warning.OperationOnSameValues, []}, + {Credo.Check.Warning.OperationWithConstantResult, []}, + {Credo.Check.Warning.RaiseInsideRescue, []}, + {Credo.Check.Warning.SpecWithStruct, []}, + {Credo.Check.Warning.StructFieldAmount, []}, + {Credo.Check.Warning.UnsafeExec, []}, + {Credo.Check.Warning.UnusedEnumOperation, []}, + {Credo.Check.Warning.UnusedFileOperation, []}, + {Credo.Check.Warning.UnusedKeywordOperation, []}, + {Credo.Check.Warning.UnusedListOperation, []}, + {Credo.Check.Warning.UnusedMapOperation, []}, + {Credo.Check.Warning.UnusedPathOperation, []}, + {Credo.Check.Warning.UnusedRegexOperation, []}, + {Credo.Check.Warning.UnusedStringOperation, []}, + {Credo.Check.Warning.UnusedTupleOperation, []}, + {Credo.Check.Warning.WrongTestFilename, []}, + + # + ## Custom Checks + # + {Firehose.Checks.NoConnShadowing, []} + ], + disabled: [ + # + # Checks scheduled for next check update (opt-in for now) + {Credo.Check.Refactor.UtcNowTruncate, []}, + + # + # Controversial and experimental checks (opt-in, just move the check to `:enabled` + # and be sure to use `mix credo --strict` to see low priority 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.CondInsteadOfIfElse, []}, + {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.PassAsyncInTestCases, []}, + {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, []} + # {Credo.Check.Warning.UnusedOperation, [{MyMagicModule, [:fun1, :fun2]}]} + + # {Credo.Check.Refactor.MapInto, []}, + + # + # Custom checks can be created using `mix credo.gen.check`. + # + ] + } + } + ] +} diff --git a/app/lib/firehose/checks/no_conn_shadowing.ex b/app/lib/firehose/checks/no_conn_shadowing.ex new file mode 100644 index 0000000..405dca5 --- /dev/null +++ b/app/lib/firehose/checks/no_conn_shadowing.ex @@ -0,0 +1,44 @@ +defmodule Firehose.Checks.NoConnShadowing do + use Credo.Check, + base_priority: :normal, + category: :readability, + explanations: [ + check: """ + Conn shadowing (`conn = get(conn, ...)`) makes Phoenix controller tests + noisy. Use pipe chains instead: + + body = conn |> get("/path") |> html_response(200) + + Run `./refactor_conn_aliasing.sh ` to fix automatically. + """ + ] + + @http_verbs ~w(get post put patch delete head options)a + + @impl true + def run(%SourceFile{} = source_file, params) do + issue_meta = IssueMeta.for(source_file, params) + + source_file + |> Credo.Code.prewalk(&traverse(&1, &2, issue_meta)) + |> Enum.reverse() + end + + defp traverse({:=, meta, [{:conn, _, _}, {verb, _, [{:conn, _, _} | _]}]} = ast, issues, issue_meta) + when verb in @http_verbs do + issue = issue_for(issue_meta, meta[:line], verb) + {ast, [issue | issues]} + end + + defp traverse(ast, issues, _issue_meta) do + {ast, issues} + end + + defp issue_for(issue_meta, line_no, verb) do + format_issue( + issue_meta, + message: "Conn shadowing detected (`conn = #{verb}(conn, ...)`). Run `./refactor_conn_aliasing.sh ` to fix.", + line_no: line_no + ) + end +end