Accept filename which is based on the fully qualified receiver class …

…plus name of an extension function when it is the only top level declaration in a file Closes pinterest#1521
paul-dingemans · Jun 27, 2022 · 31cad30 · 31cad30
1 parent a4358e7
commit 31cad30
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Showing 2 changed files with 56 additions and 10 deletions.
diff --git a/...nt-ruleset-standard/src/main/kotlin/com/pinterest/ktlint/ruleset/standard/FilenameRule.kt b/...nt-ruleset-standard/src/main/kotlin/com/pinterest/ktlint/ruleset/standard/FilenameRule.kt
@@ -86,7 +86,11 @@ public class FilenameRule : Rule(
                         topLevelDeclaration
                             .identifier
                             .toPascalCase()
-                    fileName.shouldMatchFileName(pascalCaseIdentifier, emit)
+                    val pascalCaseQualifier =
+                        topLevelDeclaration
+                            .qualifier
+                            ?.toPascalCase()
+                    fileName.shouldMatchFileName(pascalCaseQualifier, pascalCaseIdentifier, emit)
                 } else {
                     fileName.shouldMatchPascalCase(emit)
                 }
@@ -139,15 +143,23 @@ public class FilenameRule : Rule(
         replaceFirstChar { it.uppercaseChar() }
 
     private fun String.shouldMatchFileName(
+        qualifier: String?,
         filename: String,
         emit: (offset: Int, errorMessage: String, canBeAutoCorrected: Boolean) -> Unit
     ) {
-        if (this != filename) {
-            emit(
-                0,
-                "File '$this.kt' contains a single top level declaration and should be named '$filename.kt'",
-                false
-            )
+        when {
+            qualifier == null && this != filename ->
+                emit(
+                    0,
+                    "File '$this.kt' contains a single top level declaration and should be named '$filename.kt'",
+                    false
+                )
+            qualifier != null && this != "$qualifier$filename" ->
+                emit(
+                    0,
+                    "File '$this.kt' contains a single top level declaration and should be named '$filename.kt' or '$qualifier$filename.kt'",
+                    false
+                )
         }
     }
 
@@ -161,14 +173,26 @@ public class FilenameRule : Rule(
 
     private data class TopLevelDeclaration(
         val elementType: IElementType,
-        val identifier: String
+        val identifier: String,
+        val qualifier: String? = null
     )
 
     private fun ASTNode.toTopLevelDeclaration(): TopLevelDeclaration? =
         findChildByType(IDENTIFIER)
             ?.text
             ?.removeSurrounding("`")
-            ?.let { TopLevelDeclaration(elementType, it) }
+            ?.let {
+                if (this.elementType == FUN) {
+                    val typeReference =
+                        this
+                            .findChildByType(TYPE_REFERENCE)
+                            ?.text
+                            ?.replace(".", "")
+                    TopLevelDeclaration(elementType, it, typeReference)
+                } else {
+                    TopLevelDeclaration(elementType, it)
+                }
+            }
 
     private companion object {
         val pascalCaseRegEx = Regex("""^[A-Z][A-Za-z\d]*$""")

diff --git a/...uleset-standard/src/test/kotlin/com/pinterest/ktlint/ruleset/standard/FilenameRuleTest.kt b/...uleset-standard/src/test/kotlin/com/pinterest/ktlint/ruleset/standard/FilenameRuleTest.kt
@@ -82,7 +82,6 @@ class FilenameRuleTest {
         strings = [
             "object Foo",
             "typealias Foo = String",
-            "fun String.foo() = {}",
             "fun foo() = {}"
         ]
     )
@@ -94,6 +93,29 @@ class FilenameRuleTest {
             .hasLintViolationWithoutAutoCorrect(1, 1, "File '$UNEXPECTED_FILE_NAME' contains a single top level declaration and should be named 'Foo.kt'")
     }
 
+    @Test
+    fun `Issue 1521 - Given a file containing a single toplevel extension function on a standard receiver class defined in another file then allow the file to be named based upon the fully qualified receiver suffixed with the function name`() {
+        val code =
+            """
+            fun String.foo() {}
+            """.trimIndent()
+        fileNameRuleAssertThat(code)
+            .asFileWithPath(UNEXPECTED_FILE_NAME)
+            .hasLintViolationWithoutAutoCorrect(1, 1, "File '$UNEXPECTED_FILE_NAME' contains a single top level declaration and should be named 'Foo.kt' or 'StringFoo.kt'")
+    }
+
+    @Test
+    fun `Issue 1521 - Given a file containing a single toplevel extension function on a custom receiver class defined in another file then allow the file to be named based upon the fully qualified receiver suffixed with the function name`() {
+        val code =
+            """
+            fun Foo.Status.image() {}
+            """.trimIndent()
+        fileNameRuleAssertThat(code)
+            .asFileWithPath(UNEXPECTED_FILE_NAME)
+            .hasLintViolationWithoutAutoCorrect(1, 1, "File '$UNEXPECTED_FILE_NAME' contains a single top level declaration and should be named 'Image.kt' or 'FooStatusImage.kt'")
+    }
+
+
     @ParameterizedTest(name = "Top level declaration: {0}")
     @ValueSource(
         strings = [