Make no_empty_block rule opt-in and add configurations (#5685)

CHANGELOG.md

@@ -36,7 +36,7 @@
   [Martin Redington](https://github.com/mildm8nnered)
   [#5552](https://github.com/realm/SwiftLint/issues/5552)
 
-* Add `no_empty_block` default rule to validate that code blocks are not empty.
+* Add `no_empty_block` opt-in rule to validate that code blocks are not empty.
   They should at least contain a comment.  
   [Ueeek](https://github.com/Ueeek)
   [#5615](https://github.com/realm/SwiftLint/issues/5615)

Source/SwiftLintBuiltInRules/Rules/Idiomatic/NoEmptyBlockRule.swift

@@ -1,8 +1,9 @@
+import SwiftLintCore
 import SwiftSyntax
 
 @SwiftSyntaxRule
-struct NoEmptyBlockRule: Rule {
-    var configuration = SeverityConfiguration<Self>(.warning)
+struct NoEmptyBlockRule: OptInRule {
+    var configuration = NoEmptyBlockConfiguration()
 
     static let description = RuleDescription(
         identifier: "no_empty_block",
@@ -11,85 +12,122 @@ struct NoEmptyBlockRule: Rule {
         kind: .idiomatic,
         nonTriggeringExamples: [
             Example("""
+            func f() {
+                /* do something */
+            }
+
             var flag = true {
                 willSet { /* do something */ }
             }
             """),
+
             Example("""
-            do {
-                /* do something */
-            } catch {
-                /* do something */
+            class Apple {
+                init() { /* do something */ }
+
+                deinit { /* do something */ }
             }
             """),
+
             Example("""
-            defer {
+            for _ in 0..<10 { /* do something */ }
+
+            do {
+                /* do something */
+            } catch {
                 /* do something */
             }
-            """),
-            Example("""
-            deinit { /* do something */ }
-            """),
-            Example("""
-            for _ in 0..<10 { /* do something */ }
-            """),
-            Example("""
+
             func f() {
-                /* do something */
+                defer {
+                    /* do something */
+                }
+                print("other code")
             }
-            """),
-            Example("""
+
             if flag {
                 /* do something */
             } else {
                 /* do something */
             }
+
+            repeat { /* do something */ } while (flag)
+
+            while i < 10 { /* do something */ }
             """),
+
             Example("""
-            init() { /* do something */ }
-            """),
+            func f() {}
+
+            var flag = true {
+                willSet {}
+            }
+            """, configuration: ["disabled_block_types": ["function_bodies"]]),
+
             Example("""
-            repeat { /* do something */ } while (flag)
-            """),
+            class Apple {
+                init() {}
+
+                deinit {}
+            }
+            """, configuration: ["disabled_block_types": ["initializer_bodies"]]),
+
             Example("""
-            while i < 10 { /* do something */ }
-            """),
+            for _ in 0..<10 {}
+
+            do {
+            } catch {
+            }
+
+            func f() {
+                defer {}
+                print("other code")
+            }
+
+            if flag {
+            } else {
+            }
+
+            repeat {} while (flag)
+
+            while i < 10 {}
+            """, configuration: ["disabled_block_types": ["statement_blocks"]]),
         ],
         triggeringExamples: [
             Example("""
+            func f() ↓{}
+
             var flag = true {
                 willSet ↓{}
             }
             """),
+
             Example("""
-            do ↓{
-            } catch ↓{
+            class Apple {
+                init() ↓{}
+
+                deinit ↓{}
             }
             """),
-            Example("""
-            defer ↓{}
-            """),
-            Example("""
-            deinit ↓{}
-            """),
+
             Example("""
             for _ in 0..<10 ↓{}
-            """),
-            Example("""
-            func f() ↓{}
-            """),
-            Example("""
+
+            do ↓{
+            } catch ↓{
+            }
+
+            func f() {
+                defer ↓{}
+                print("other code")
+            }
+
             if flag ↓{
             } else ↓{
             }
-            """),
-            Example("""
-            init() ↓{}
-            """),
-            Example("""
+
             repeat ↓{} while (flag)
-            """),
-            Example("""
+
             while i < 10 ↓{}
             """),
         ]
@@ -99,16 +137,36 @@ struct NoEmptyBlockRule: Rule {
 private extension NoEmptyBlockRule {
     final class Visitor: ViolationsSyntaxVisitor<ConfigurationType> {
         override func visitPost(_ node: CodeBlockSyntax) {
-            // No need to show a warning since Empty Block of `guard` is compile error.
-            guard node.parent?.kind != .guardStmt else { return }
+            if let codeBlockType = node.codeBlockType, configuration.enabledBlockTypes.contains(codeBlockType) {
+                validate(node: node)
+            }
+        }
 
+        func validate(node: CodeBlockSyntax) {
             guard node.statements.isEmpty,
                   !node.leftBrace.trailingTrivia.containsComments,
                   !node.rightBrace.leadingTrivia.containsComments else {
                 return
             }
-
             violations.append(node.leftBrace.positionAfterSkippingLeadingTrivia)
         }
     }
 }
+
+private extension CodeBlockSyntax {
+    var codeBlockType: NoEmptyBlockConfiguration.CodeBlockType? {
+        switch parent?.kind {
+        case .functionDecl, .accessorDecl:
+            .functionBodies
+        case .initializerDecl, .deinitializerDecl:
+            .initializerBodies
+        case .forStmt, .doStmt, .whileStmt, .repeatStmt, .ifExpr, .catchClause, .deferStmt:
+            .statementBlocks
+        case .guardStmt:
+            // No need to handle this case since Empty Block of `guard` is compile error.
+            nil
+        default:
+            nil
+        }
+    }
+}

Source/SwiftLintBuiltInRules/Rules/RuleConfigurations/NoEmptyBlockConfiguration.swift

@@ -0,0 +1,25 @@
+import SwiftLintCore
+
+@AutoApply
+struct NoEmptyBlockConfiguration: SeverityBasedRuleConfiguration {
+    typealias Parent = NoEmptyBlockRule
+
+    @MakeAcceptableByConfigurationElement
+    enum CodeBlockType: String, CaseIterable {
+        case functionBodies = "function_bodies"
+        case initializerBodies = "initializer_bodies"
+        case statementBlocks = "statement_blocks"
+
+        static let all = Set(allCases)
+    }
+
+    @ConfigurationElement(key: "severity")
+    private(set) var severityConfiguration = SeverityConfiguration<Parent>(.warning)
+
+    @ConfigurationElement(key: "disabled_block_types")
+    private(set) var disabledBlockTypes: [CodeBlockType] = []
+
+    var enabledBlockTypes: Set<CodeBlockType> {
+        CodeBlockType.all.subtracting(disabledBlockTypes)
+    }
+}

Tests/IntegrationTests/default_rule_configurations.yml

@@ -336,6 +336,7 @@ nimble_operator:
   severity: warning
 no_empty_block:
   severity: warning
+  disabled_block_types: []
 no_extension_access_modifier:
   severity: error
 no_fallthrough_only:

Tests/SwiftLintFrameworkTests/NoEmptyBlockConfigurationTests.swift

@@ -0,0 +1,54 @@
+@testable import SwiftLintBuiltInRules
+@testable import SwiftLintCore
+import XCTest
+
+final class NoEmptyBlockConfigurationTests: SwiftLintTestCase {
+    func testDefaultConfiguration() {
+        let config = NoEmptyBlockConfiguration()
+        XCTAssertEqual(config.severityConfiguration.severity, .warning)
+        XCTAssertEqual(config.enabledBlockTypes, NoEmptyBlockConfiguration.CodeBlockType.all)
+    }
+
+    func testApplyingCustomConfiguration() throws {
+        var config = NoEmptyBlockConfiguration()
+        try config.apply(
+            configuration: [
+                "severity": "error",
+                "disabled_block_types": ["function_bodies"],
+            ] as [String: any Sendable]
+        )
+        XCTAssertEqual(config.severityConfiguration.severity, .error)
+        XCTAssertEqual(config.enabledBlockTypes, Set([.initializerBodies, .statementBlocks]))
+    }
+
+    func testInvalidKeyInCustomConfiguration() {
+        var config = NoEmptyBlockConfiguration()
+        XCTAssertEqual(
+            try Issue.captureConsole { try config.apply(configuration: ["invalidKey": "error"]) },
+            "warning: Configuration for 'no_empty_block' rule contains the invalid key(s) 'invalidKey'."
+        )
+    }
+
+    func testInvalidTypeOfCustomConfiguration() {
+        var config = NoEmptyBlockConfiguration()
+        checkError(Issue.invalidConfiguration(ruleID: NoEmptyBlockRule.description.identifier)) {
+            try config.apply(configuration: "invalidKey")
+        }
+    }
+
+    func testInvalidTypeOfValueInCustomConfiguration() {
+        var config = NoEmptyBlockConfiguration()
+        checkError(Issue.invalidConfiguration(ruleID: NoEmptyBlockRule.description.identifier)) {
+            try config.apply(configuration: ["severity": "foo"])
+        }
+    }
+
+    func testConsoleDescription() throws {
+        var config = NoEmptyBlockConfiguration()
+        try config.apply(configuration: ["disabled_block_types": ["initializer_bodies", "statement_blocks"]])
+        XCTAssertEqual(
+            RuleConfigurationDescription.from(configuration: config).oneLiner(),
+            "severity: warning; disabled_block_types: [initializer_bodies, statement_blocks]"
+        )
+    }
+}