Add an option to test lint rules on the full pipeline only.

Standalone lint visitors don't check for swift-format-ignore markers,
so any test cases that use those markers will return different
results between standalone vs full pipeline.

Author: shawnhyam

Tests/SwiftFormatTests/Rules/DontRepeatTypeInStaticPropertiesTests.swift

@@ -75,4 +75,23 @@ final class DontRepeatTypeInStaticPropertiesTests: LintOrFormatRuleTestCase {
       ]
     )
   }
+
+
+  func testIgnoreSingleDecl() {
+    assertLint(
+      DontRepeatTypeInStaticProperties.self,
+      pipelineOnly: true,
+        """
+        struct Foo {
+          // swift-format-ignore: DontRepeatTypeInStaticProperties
+          static let defaultFoo: Int
+          static let 1️⃣alternateFoo: Int
+        }
+        """,
+      findings: [
+        FindingSpec("1️⃣", message: "remove the suffix 'Foo' from the name of the variable 'alternateFoo'"),
+      ]
+    )
+  }
+
 }

Tests/SwiftFormatTests/Rules/LintOrFormatRuleTestCase.swift

@@ -13,6 +13,8 @@ class LintOrFormatRuleTestCase: DiagnosingTestCase {
   ///
   /// - Parameters:
   ///   - type: The metatype of the lint rule you wish to perform.
+  ///   - pipelineOnly: Don't run the linter on its own, only as part of the pipeline. This is
+  ///     because swift-format-ignore has no effect when running the linter standalone.
   ///   - markedSource: The input source code, which may include emoji markers at the locations
   ///     where findings are expected to be emitted.
   ///   - findings: A list of `FindingSpec` values that describe the findings that are expected to
@@ -21,6 +23,7 @@ class LintOrFormatRuleTestCase: DiagnosingTestCase {
   ///   - line: The line the test resides in (defaults to the current caller's line).
   final func assertLint<LintRule: SyntaxLintRule>(
     _ type: LintRule.Type,
+    pipelineOnly: Bool = false,
     _ markedSource: String,
     findings: [FindingSpec] = [],
     file: StaticString = #file,
@@ -42,16 +45,18 @@ class LintOrFormatRuleTestCase: DiagnosingTestCase {
       configuration: configuration,
       selection: .infinite,
       findingConsumer: { emittedFindings.append($0) })
-    let linter = type.init(context: context)
-    linter.walk(sourceFileSyntax)
-
-    assertFindings(
-      expected: findings,
-      markerLocations: markedText.markers,
-      emittedFindings: emittedFindings,
-      context: context,
-      file: file,
-      line: line)
+    if !pipelineOnly {
+      let linter = type.init(context: context)
+      linter.walk(sourceFileSyntax)
+      
+      assertFindings(
+        expected: findings,
+        markerLocations: markedText.markers,
+        emittedFindings: emittedFindings,
+        context: context,
+        file: file,
+        line: line)
+    }
 
     var emittedPipelineFindings = [Finding]()
     // Disable default rules, so only select rule runs in pipeline