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Configuring Rules

Rules are one of the core building blocks of DCM. A rule validates if your code meets a certain expectation, and what to do if it does not meet that expectation.

All rules can be configured with severity, ignorable, effort, exclude and include options, but some rules also have additional configuration options specific to that rule and are marked with ⚙️.

Enabling a Rule

To enable a rule add its id to the rules entry:

analysis_options.yaml

dcm:
  rules:
    - newline-before-return

Rule Severities

To change a rule's severity, configure the rule with one of these values:

Severity level	Description
error	By default, not assigned to any rule. Expected to represent most important issues.
warning	Assigned by default to rules that cover potential bugs.
style	Assigned by default to rules covering style issues.

analysis_options.yaml

dcm:
  rules:
    - newline-before-return:
        severity: style

Disabling Rule Ignores

To disable ignore comments for a particular rule, set ignorable: false:

analysis_options.yaml

dcm:
  rules:
    - newline-before-return:
        ignorable: false

Customizing Estimated Effort

To change the estimated effort for a particular rule, set effort (in minutes):

analysis_options.yaml

dcm:
  rules:
    - newline-before-return:
        effort: 10

Providing Additional Context

To include an additional message to the rule's default message, set message:

analysis_options.yaml

dcm:
  rules:
    - avoid-non-null-assertion:
        message: 'Use our custom function "customFn" instead.'

This will change the avoid-non-null-assertion's message to Avoid non-null assertions. Try rewriting the code without it. Use our custom function "customFn" instead..

Excluding Files

To exclude specific files from rule's analysis, configure the exclude option:

analysis_options.yaml

dcm:
  rules:
    - newline-before-return:
        exclude:
          - test/**

Excluding Files for All Rules

To exclude a file for all rules, configure the global exclude:rules: option:

analysis_options.yaml

dcm:
  exclude:
    rules:
      - test/**
      - lib/src/some_file.dart

Including Files

To include specific files to rule's analysis, configure the rule include option:

analysis_options.yaml

dcm:
  rules:
    - newline-before-return:
        include:
          - test/**

info

All files are included by default.

Disabling a Rule

If you include an analysis options file (which has DCM configuration) or use a preset, you might want to disable some of the included rules. Disabling individual rules is similar to enabling them, but the name of a rule should be followed by either : false or : true.

Here's an example of an analysis options file that has a disabled rule:

analysis_options.yaml

include: package:my_lints/all.yaml

dcm:
  rules:
    - newline-before-return: false