Flutter Static Code Analysis Tools To Pair For DevOPS

For DevOPS you should pair both lints and code metrics together as part of your flutter devOPS.

Compilers are lazy and thus the efforts we have to manually do to move run time exceptions to compilable executable code involves some static analysis to get warnings when our code sucks and needs to be changed. The other aspect is getting some code metrics to make the right architecture design decisions.

The two tools I will show to pair up in static code analysis is Pascal's lint package and Dart Code Linter. Pascal's lint package fully implements the Effective Dart best practices. While the Dart Code Linter package implements code metrics to measures to be used in architecture code choice decisions.

Pascal's Lint Package

 The myth is that the Flutter Lints package that is the default for Flutter projects fully covers the guidelines in Effective Dart guide:

  Effective Dart Guide

 

The Flutter Lints package only covers 10 percent of the Effective Dart guide, but the Dart SDK and Flutter SDK teams have created more lints that do in fact cover the rest of Effective Dart guidance. Pascal has curated that full list of both Dart and Flutter Lints into a package called Lint:

 Lint

 

One includes the strict lint import at the top of the analysis options YAML file and includes the dependency in the dev dependencies block in the pubspec YAML file.

Now I use the Dart Code Linter to add more lint rules and code metrics to the static analysis.

 Dart Code Linter

Dart Code Linter is a soft fork of Dart Code Metrics when it was an open source project.

  Dart Code Linter

 

  ### It has BIN component beyond the package, so one has to put the dependency in the dev dependencies block and in the terminal type the below command set and once the DCL settings is put in the analysis options file then in the terminal you will type the below command set:

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	To activate in terminal type
	dart pub global activate dart_code_linter

view raw activate.txt hosted with ❤ by GitHub

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	# This file configures the analyzer, which statically analyzes Dart code to
	# check for errors, warnings, and lints.
	#
	# The issues identified by the analyzer are surfaced in the UI of Dart-enabled
	# IDEs (https://dart.dev/tools#ides-and-editors). The analyzer can also be
	# invoked from the command line by running `flutter analyze`.
	# The following line activates a set of recommended lints for Flutter apps,
	# packages, and plugins designed to encourage good coding practices.
	# Lint package has three, strict, casual and package
	include: package:lint/strict.yaml
	analyzer:
	# for freezed when json serializable is used
	errors:
	invalid_annotation_target: ignore
	exclude:
	- "**/*.g.dart"
	- "**.freezed.dart"
	- "build/**"
	- "lib/generated/**"
	plugins:
	- dart_code_linter
	# as of 10 13 23 they have not documented
	# config settings for certain rules so
	# those rules are not included for now
	dart_code_linter:
	# I do not use extends but have implemented my
	# own extra lint rule list
	anti-patterns:
	- long-method
	- long-parameter-list
	metrics:
	cyclomatic-complexity: 20
	halstead-volume: 150
	maintainability-index: 50
	maximum-nesting-level: 5
	number-of-parameters: 4
	number-of-methods: 10
	source-lines-of-code: 250
	technical-debt:
	threshold: 1
	todo-cost: 161
	ignore-cost: 320
	ignore-for-file-cost: 396
	as-dynamic-cost: 322
	deprecated-annotations-cost: 37
	file-nullsafety-migration-cost: 41
	unit-type: "USD"
	metrics-exclude:
	- test/**
	# full rules list is at
	# https://github.com/bancolombia/dart-code-linter/wiki/Rules
	rules:
	#dart
	- avoid-substring
	# used with sort_child_properties_last
	- arguments-ordering:
	child-last: true
	- avoid-banned-file-names:
	entries:
	- .*example.dart
	# these are used to help enforce arch decisions
	# - avoid-banned-imports
	# - avoid-banned-types
	- avoid-cascade-after-if-null
	- avoid-collection-methods-with-unrelated-types
	- avoid-duplicate-exports
	- avoid-dynamic
	- avoid-global-state
	# - avoid-ignoring-return-values
	- avoid-importing-entrypoint-exports:
	only-in-src: true
	# - avoid-late-keyword:
	# allow-initialized: true
	- avoid-long-files:
	max-length: 500
	- avoid-long-functions:
	max-length: 80
	ignored-names:
	- some
	- name
	- avoid-long-parameter-list:
	ignore-optional: true
	max-amount: 3
	ignored-names:
	- some
	- name
	- avoid-long-records:
	max-amount: 6
	- avoid-missing-enum-constant-in-map
	- avoid-nested-conditional-expressions
	- avoid-nested-records:
	acceptable-level: 2
	- avoid-nested-switch-expressions:
	acceptable-level: 1
	- avoid-non-ascii-symbols
	# - avoid-non-null-assertion:
	# skip-checked-fields: true
	- avoid-nullable-interpolation:
	ignored-invocations:
	- log
	- debugPrint
	# - avoid-passing-async-when-sync-expected
	# - avoid-redundant-async
	- avoid-shadowing:
	ignore-static: true
	ignore-fields: true
	ignore-parameters: true
	ignored-names:
	- some
	- name
	- avoid-similar-names:
	show-similarity: true
	similarity-threshold: 0.9
	ignored-names:
	- some
	- name
	- avoid-throw-in-catch-block
	- avoid-top-level-members-in-tests
	- avoid-unnecessary-type-assertions
	- avoid-unnecessary-type-casts
	- avoid-unrelated-type-assertions:
	ignore-mixins: false
	- avoid-unused-instances:
	ignored-instances:
	- Timer
	- SomeOtherClass
	- avoid-unused-parameters:
	ignore-inline-functions: false
	# - ban-name
	# - banned-usage
	- binary-expression-operand-order
	- double-literal-format
	- format-comment:
	only-doc-comments: true
	ignored-patterns:
	- ^ cSpell.*
	# - match-class-name-pattern:
	# entries:
	# - path: '.*state.dart'
	# pattern: 'State$'
	# ignore-private: true
	- missing-test-assertion:
	include-assertions:
	- verify
	include-methods:
	- customTest
	- move-records-to-typedefs:
	min-fields: 5
	min-occurrences: 3
	- newline-before-return
	- no-boolean-literal-compare:
	allow-false: true
	# - no-empty-block
	- no-equal-arguments:
	ignored-parameters:
	- height
	- width
	- no-equal-then-else
	# - no-magic-number:
	# allowed: [3.14, 100, 12]
	# allow-only-once: true
	- no-object-declaration
	- parameters-ordering:
	required: 'first'
	default: 'last'
	- prefer-async-await
	- prefer-commenting-analyzer-ignores
	- prefer-conditional-expressions:
	ignore-nested: true
	- prefer-correct-error-name:
	allowed-names:
	- err
	# - prefer-correct-identifier-length:
	# exceptions: [ 'a' ]
	# max-identifier-length: 30
	# min-identifier-length: 4
	- prefer-correct-switch-length:
	min-length: 5
	max-length: 20
	- prefer-correct-test-file-name
	- prefer-correct-type-name:
	excluded: [ 'exampleExclude' ]
	min-length: 3
	max-length: 40
	- prefer-declaring-const-constructor:
	allow-one: true
	- prefer-enums-by-name
	- prefer-first
	- prefer-immediate-return
	- prefer-iterable-of
	- prefer-last
	- prefer-match-file-name
	- prefer-moving-to-variable:
	allowed-duplicated-chains: 3
	- prefer-named-boolean-parameters:
	ignore-single: true
	ignore-single-boolean: true
	- prefer-static-class
	- prefer-trailing-comma:
	break-on: 2
	- unnecessary-trailing-comma:
	max-width: 100
	- avoid-double-slash-imports
	- avoid-unnecessary-conditionals
	# flutter
	- prefer-define-hero-tag
	- always-remove-listener
	- avoid-border-all
	- avoid-missing-image-alt:
	allow-empty: true
	- avoid-returning-widgets:
	ignored-names:
	- testFunction
	ignored-annotations:
	- allowedAnnotation
	- avoid-shrink-wrap-in-lists
	- avoid-expanded-as-spacer
	- avoid-wrapping-in-padding
	- check-for-equals-in-render-object-setters
	- consistent-update-render-object
	- dispose-fields:
	ignore-blocs: false
	- prefer-const-border-radius
	- prefer-correct-edge-insets-constructor
	# - prefer-extracting-callbacks
	- prefer-single-widget-per-file
	- prefer-using-list-view
	- use-setstate-synchronously
	# Intl, uncomment when needed
	# - prefer-intl-name
	# - prefer-provide-intl-description
	# - provide-correct-intl-args
	- member-ordering:
	order:
	- constructors
	- public-fields
	- private-fields
	- close-method
	- dispose-method
	widgets-order:
	- constructor
	- build-method
	- init-state-method
	- did-change-dependencies-method
	- did-update-widget-method
	- dispose-method
	linter:
	# The lint rules applied to this project can be customized in the
	# section below to disable rules from the `package:flutter_lints/flutter.yaml`
	# included above or to enable additional rules. A list of all available lints
	# and their documentation is published at
	# https://dart-lang.github.io/linter/lints/index.html.
	#
	# Instead of disabling a lint rule for the entire project in the
	# section below, it can also be suppressed for a single line of code
	# or a specific dart file by using the `// ignore: name_of_lint` and
	# `// ignore_for_file: name_of_lint` syntax on the line or in the file
	# producing the lint.
	rules:
	# avoid_print: false # Uncomment to disable the `avoid_print` rule
	# prefer_single_quotes: true # Uncomment to enable the `prefer_single_quotes` rule
	# Additional information about this file can be found at
	# https://dart.dev/guides/language/analysis-options

view raw analysis_options.yaml hosted with ❤ by GitHub

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	name: metrics_lint_demo
	description: "A new Flutter project."
	# Prevent accidental publishing to pub.dev.
	publish_to: 'none'
	version: 1.0.0+1
	environment:
	sdk: '>=3.2.0-210.2.beta <4.0.0'
	dependencies:
	flutter:
	sdk: flutter
	flutter_localizations:
	sdk: flutter
	dev_dependencies:
	flutter_test:
	sdk: flutter
	flutter_launcher_icons: "^0.13.1"
	# more opinionated lints than flutter lints
	lint: ^2.1.2
	# replaces DCM
	dart_code_linter: ^1.1.1
	flutter:
	uses-material-design: true
	# Enable generation of localized Strings from arb files.
	generate: true
	assets:
	# Add assets from the images directory to the application.
	- assets/images/

view raw pubspec.yaml hosted with ❤ by GitHub

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	after creating reports folder in app project in
	terminal type
	dart run dart_code_linter:metrics analyze lib -o reports/code_metrics -r html

view raw report_gen.txt hosted with ❤ by GitHub

 And that will produce these reports that then we can use to make code architecture decisions:

   Index HTML Code Metrics Report

 

 Thoughts

 The general idea here is to through the whole devOPS stack including testing so that I can do app builds the Google way where one only uses actual targeted devices during the final release builds of the app through CI services like CodeMagic. Or to put it another way testing is focused on non-instrumented and non-integration testing. And of course you can combine that with using a desktop tower Intel 13900K or 14900K and get Apple M3 build times without paying the Apple tax.

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