Repository: cqfn/diKTat (kotlin)

Issue:
`WRONG_INDENTATION`: running `mvn diktat:fix` adds whitespace to string literals
Consider this code fragment:

```kotlin
    @Test
    fun `checking that suppression with ignore everything works`() {
        val code =
                """
                    @Suppress("diktat")
                    fun foo() {
                        val a = 1
                    }
                """.trimIndent()
        lintMethod(code)
    }
```

Whenever the code doesn't match the settings of DiKTat (i.e., in the above example, the body of the `code` expression uses _continuation indent_ while `extendedIndentAfterOperators` is false), running `mvn diktat:fix` is expected to re-format the code.

While doing so (particularly, when `WRONG_INDENTATION` check is **on**), it sometimes adds extra whitespace **around** and **within** string literals, i. e. 

```kotlin
                    @Suppress("diktat")
```

may become

```kotlin
                    @Suppress(    "    diktat    "    )
```

Moreover, the operation is not idempotent, so running `mvn diktat:fix` consecutively yet increases the amount of whitespace.

Sometimes excessively long lines get wrapped, and this may even result in non-compilable code:

```kotlin
                    @Suppress(    "    diktat
    "    )
```

Screenshot:

![](https://user-images.githubusercontent.com/58667063/171014226-54696a6a-319d-42e8-9b14-b74fd30ee8f5.png)

Originally from [this comment](https://github.com/saveourtool/diktat/issues/1330#issue-1252828874).

Pull request:
### What's done:

 * Now, only those `LITERAL_STRING_TEMPLATE_ENTRY` nodes which immediately
   follow a newline are indented.
 * Additionally, with this change, `trimIndent()` and `trimMargin(...)` calls
   are more reliably detected.
 * This fixes #1347.

## Actions checklist
* [X] Added tests on fixers

Patch:
diff --git a/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/chapter3/files/IndentationRule.kt b/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/chapter3/files/IndentationRule.kt
index 7fe952fac8..afd0b56fcf 100644
--- a/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/chapter3/files/IndentationRule.kt
+++ b/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/chapter3/files/IndentationRule.kt
@@ -37,6 +37,7 @@ import com.pinterest.ktlint.core.ast.ElementType.CLOSING_QUOTE
 import com.pinterest.ktlint.core.ast.ElementType.DOT_QUALIFIED_EXPRESSION
 import com.pinterest.ktlint.core.ast.ElementType.ELSE
 import com.pinterest.ktlint.core.ast.ElementType.FILE
+import com.pinterest.ktlint.core.ast.ElementType.IDENTIFIER
 import com.pinterest.ktlint.core.ast.ElementType.LBRACE
 import com.pinterest.ktlint.core.ast.ElementType.LBRACKET
 import com.pinterest.ktlint.core.ast.ElementType.LITERAL_STRING_TEMPLATE_ENTRY
@@ -46,6 +47,7 @@ import com.pinterest.ktlint.core.ast.ElementType.LONG_TEMPLATE_ENTRY_START
 import com.pinterest.ktlint.core.ast.ElementType.LPAR
 import com.pinterest.ktlint.core.ast.ElementType.RBRACE
 import com.pinterest.ktlint.core.ast.ElementType.RBRACKET
+import com.pinterest.ktlint.core.ast.ElementType.REFERENCE_EXPRESSION
 import com.pinterest.ktlint.core.ast.ElementType.REGULAR_STRING_PART
 import com.pinterest.ktlint.core.ast.ElementType.RPAR
 import com.pinterest.ktlint.core.ast.ElementType.SAFE_ACCESS_EXPRESSION
@@ -244,7 +246,9 @@ class IndentationRule(configRules: List<RulesConfig>) : DiktatRule(
     }
 
     /**
-     * Checks if it is triple-quoted string template with trimIndent() or trimMargin() function.
+     * Checks if it is a triple-quoted string template with
+     * [trimIndent()][String.trimIndent] or [trimMargin(...)][String.trimMargin]
+     * function.
      */
     private fun checkStringLiteral(
         whiteSpace: PsiWhiteSpace,
@@ -256,10 +260,7 @@ class IndentationRule(configRules: List<RulesConfig>) : DiktatRule(
             nextNodeDot.elementType == DOT_QUALIFIED_EXPRESSION &&
             nextNodeDot.firstChildNode.elementType == STRING_TEMPLATE &&
             nextNodeDot.firstChildNode.text.startsWith("\"\"\"") &&
-            nextNodeDot.findChildByType(CALL_EXPRESSION)?.text?.let {
-                it == "trimIndent()" ||
-                    it == "trimMargin()"
-            } == true) {
+            nextNodeDot.findChildByType(CALL_EXPRESSION).isTrimIndentOrMarginCall()) {
             fixStringLiteral(nextNodeDot.firstChildNode, expectedIndent, actualIndent)
         }
     }
@@ -290,40 +291,60 @@ class IndentationRule(configRules: List<RulesConfig>) : DiktatRule(
         actualIndent: Int
     ) {
         val templateEntries = stringTemplate.getAllChildrenWithType(LITERAL_STRING_TEMPLATE_ENTRY)
-        templateEntries.asSequence().filterIndexed { index, templateEntry ->
+        val templateEntriesLastIndex = templateEntries.size - 1
+        var templateEntryFollowingNewline = false
+
+        templateEntries.forEachIndexed { index, templateEntry ->
             val text = templateEntry.text
-            val containsNewline = text.contains(NEWLINE)
 
-            if (containsNewline) {
+            when {
+                text.contains(NEWLINE) -> {
+                    /*
+                     * Set the flag.
+                     */
+                    templateEntryFollowingNewline = true
+
+                    /*
+                     * In real-life cases observed, whenever a `LITERAL_STRING_TEMPLATE_ENTRY`
+                     * _contains_ a newline character, it is _exactly_ a newline character.
+                     */
+                    check(text.length == 1) {
+                        val escapedText = text.replace(NEWLINE.toString(), "\\n")
+
+                        "A LITERAL_STRING_TEMPLATE_ENTRY at index $index contains extra characters in addition to the newline, " +
+                            "entry: \"$escapedText\", " +
+                            "string template: ${stringTemplate.text}"
+                    }
+                }
+
                 /*
-                 * In real-life cases observed, whenever a `LITERAL_STRING_TEMPLATE_ENTRY`
-                 * _contains_ a newline character, it is _exactly_ a newline character.
+                 * This is the last string template fragment which is usually followed
+                 * with the closing `"""` and the `.trimIndent()` or `.trimMargin(...)` call.
                  */
-                check(text.length == 1) {
-                    val escapedText = text.replace(NEWLINE.toString(), "\\n")
+                index == templateEntriesLastIndex -> {
+                    val lastRegularStringPart = templateEntries.last().firstChildNode as LeafPsiElement
+                    lastRegularStringPart.checkRegularStringPart().apply {
+                        val textWithoutIndent = text.trimStart()
+                        rawReplaceWithText(expectedIndent.spaces + textWithoutIndent)
+                    }
+                }
 
-                    "A LITERAL_STRING_TEMPLATE_ENTRY at index $index contains extra characters in addition to the newline, " +
-                        "entry: \"$escapedText\", " +
-                        "string template: ${stringTemplate.text}"
+                /*
+                 * Either this is the very first string template entry, or an
+                 * entry which immediately follows the newline.
+                 */
+                index == 0 || templateEntryFollowingNewline -> {
+                    fixFirstTemplateEntries(
+                        templateEntry,
+                        expectedIndent = expectedIndent,
+                        actualIndent = actualIndent)
+
+                    /*
+                     * Re-set the flag.
+                     */
+                    templateEntryFollowingNewline = false
                 }
             }
-
-            !containsNewline
-        }.forEach { templateEntry ->
-            fixFirstTemplateEntries(
-                templateEntry,
-                expectedIndent = expectedIndent,
-                actualIndent = actualIndent)
-        }
-
-        /*
-         * This is the last string template fragment which is usually followed
-         * with the closing `"""` and the `.trimIndent()` or `.trimMargin()` call.
-         */
-        val lastRegularStringPart = templateEntries.last().firstChildNode as LeafPsiElement
-        lastRegularStringPart.checkRegularStringPart().apply {
-            val textWithoutIndent = text.trimStart()
-            rawReplaceWithText(expectedIndent.spaces + textWithoutIndent)
         }
     }
 
@@ -368,9 +389,8 @@ class IndentationRule(configRules: List<RulesConfig>) : DiktatRule(
          */
         val regularStringPart = templateEntry.firstChildNode as LeafPsiElement
         val regularStringPartText = regularStringPart.checkRegularStringPart().text
-        val nodeStartIndentOrNegative = (regularStringPartText.leadingSpaceCount() - actualIndent).unindent()
         // shift of the node depending on its initial string template indent
-        val nodeStartIndent = nodeStartIndentOrNegative.zeroIfNegative()
+        val nodeStartIndent = (regularStringPartText.leadingSpaceCount() - actualIndent).unindent().zeroIfNegative()
 
         val isPrevStringTemplate = templateEntry.treePrev.elementType in stringLiteralTokens
         val isNextStringTemplate = templateEntry.treeNext.elementType in stringLiteralTokens
@@ -381,20 +401,11 @@ class IndentationRule(configRules: List<RulesConfig>) : DiktatRule(
 
                 // if string template is before literal_string
                 else -> regularStringPartText.trimEnd()
-
             }
 
-            else -> {
-                val textIndent = expectedIndent.indent().spaces
-
-                when {
-                    // if string template is after literal_string
-                    isNextStringTemplate -> textIndent + nodeStartIndent.spaces + regularStringPartText.trimStart()
-
-                    // if there is no string template in literal_string
-                    else -> textIndent + nodeStartIndent.spaces + regularStringPartText.trim()
-                }
-            }
+            // if string template is after literal_string
+            // or if there is no string template in literal_string
+            else -> (expectedIndent.indent() + nodeStartIndent).spaces + regularStringPartText.trimStart()
         }
 
         regularStringPart.rawReplaceWithText(correctedText)
@@ -539,6 +550,7 @@ class IndentationRule(configRules: List<RulesConfig>) : DiktatRule(
         private val decreasingTokens = listOf(RPAR, RBRACE, RBRACKET, LONG_TEMPLATE_ENTRY_END)
         private val matchingTokens = increasingTokens.zip(decreasingTokens)
         private val stringLiteralTokens = listOf(SHORT_STRING_TEMPLATE_ENTRY, LONG_STRING_TEMPLATE_ENTRY)
+        private val knownTrimFunctionPatterns = setOf("trimIndent", "trimMargin")
 
         /**
          * @return a string which consists of `N` [space][SPACE] characters.
@@ -548,6 +560,30 @@ class IndentationRule(configRules: List<RulesConfig>) : DiktatRule(
             get() =
                 SPACE.toString().repeat(n = this)
 
+        /**
+         * @return `true` if this is a [String.trimIndent] or [String.trimMargin]
+         * call, `false` otherwise.
+         */
+        private fun ASTNode?.isTrimIndentOrMarginCall(): Boolean {
+            this ?: return false
+
+            require(elementType == CALL_EXPRESSION) {
+                "The elementType of this node is $elementType while $CALL_EXPRESSION expected"
+            }
+
+            val referenceExpression = firstChildNode ?: return false
+            if (referenceExpression.elementType != REFERENCE_EXPRESSION) {
+                return false
+            }
+
+            val identifier = referenceExpression.firstChildNode ?: return false
+            if (identifier.elementType != IDENTIFIER) {
+                return false
+            }
+
+            return identifier.text in knownTrimFunctionPatterns
+        }
+
         /**
          * Checks this [REGULAR_STRING_PART] child of a [LITERAL_STRING_TEMPLATE_ENTRY].
          *


Test patch:
diff --git a/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter3/spaces/IndentationRuleFixTest.kt b/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter3/spaces/IndentationRuleFixTest.kt
index be35a8afaa..13dd478017 100644
--- a/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter3/spaces/IndentationRuleFixTest.kt
+++ b/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter3/spaces/IndentationRuleFixTest.kt
@@ -8,7 +8,6 @@ import org.cqfn.diktat.util.FixTestBase
 import generated.WarningNames
 import org.assertj.core.api.SoftAssertions.assertSoftly
 import org.intellij.lang.annotations.Language
-import org.junit.jupiter.api.Assumptions.assumeTrue
 import org.junit.jupiter.api.MethodOrderer.MethodName
 import org.junit.jupiter.api.Tag
 import org.junit.jupiter.api.Test
@@ -104,10 +103,6 @@ class IndentationRuleFixTest : FixTestBase("test/paragraph3/indentation",
     @Test
     @Tag(WarningNames.WRONG_INDENTATION)
     fun `expression body functions should be reformatted if mis-indented (extendedIndentAfterOperators = true)`(@TempDir tempDir: Path) {
-        assumeTrue(testsCanBeMuted()) {
-            "Skipping a known-to-fail test"
-        }
-
         val defaultConfig = IndentationConfig("newlineAtEnd" to false)
         val customConfig = defaultConfig.withCustomParameters("extendedIndentAfterOperators" to true)
 
@@ -126,10 +121,6 @@ class IndentationRuleFixTest : FixTestBase("test/paragraph3/indentation",
     @Test
     @Tag(WarningNames.WRONG_INDENTATION)
     fun `expression body functions should be reformatted if mis-indented (extendedIndentAfterOperators = false)`(@TempDir tempDir: Path) {
-        assumeTrue(testsCanBeMuted()) {
-            "Skipping a known-to-fail test"
-        }
-
         val defaultConfig = IndentationConfig("newlineAtEnd" to false)
         val customConfig = defaultConfig.withCustomParameters("extendedIndentAfterOperators" to false)
 
@@ -176,10 +167,6 @@ class IndentationRuleFixTest : FixTestBase("test/paragraph3/indentation",
     @Test
     @Tag(WarningNames.WRONG_INDENTATION)
     fun `no whitespace should be injected into multi-line string literals (mis-indented code reformatted, extendedIndent = true)`(@TempDir tempDir: Path) {
-        assumeTrue(testsCanBeMuted()) {
-            "Skipping a known-to-fail test"
-        }
-
         val defaultConfig = IndentationConfig("newlineAtEnd" to false)
         val customConfig = defaultConfig.withCustomParameters(*extendedIndent(enabled = true))
 
@@ -196,10 +183,6 @@ class IndentationRuleFixTest : FixTestBase("test/paragraph3/indentation",
     @Test
     @Tag(WarningNames.WRONG_INDENTATION)
     fun `no whitespace should be injected into multi-line string literals (mis-indented code reformatted, extendedIndent = false)`(@TempDir tempDir: Path) {
-        assumeTrue(testsCanBeMuted()) {
-            "Skipping a known-to-fail test"
-        }
-
         val defaultConfig = IndentationConfig("newlineAtEnd" to false)
         val customConfig = defaultConfig.withCustomParameters(*extendedIndent(enabled = false))
 
diff --git a/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter3/spaces/IndentationRuleTestMixin.kt b/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter3/spaces/IndentationRuleTestMixin.kt
index a68af9f3b5..a9d7466cd9 100644
--- a/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter3/spaces/IndentationRuleTestMixin.kt
+++ b/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter3/spaces/IndentationRuleTestMixin.kt
@@ -157,6 +157,48 @@ internal interface IndentationRuleTestMixin {
                 |}
                 """.trimMargin(),
 
+                """
+                |fun f0() {
+                |    @Language("kotlin")
+                |    val code =
+                |        ""${'"'}
+                |            |@Suppress("diktat")
+                |            |fun foo() {
+                |            |    val a = 1
+                |            |}
+                |        ""${'"'}.trimMargin()
+                |    lintMethod(code)
+                |}
+                """.trimMargin(),
+
+                """
+                |fun f1() {
+                |    @Language("kotlin")
+                |    val code =
+                |        ""${'"'}
+                |            |@Suppress("diktat")
+                |            |fun foo() {
+                |            |    val a = 1
+                |            |}
+                |        ""${'"'}.trimMargin("|")
+                |    lintMethod(code)
+                |}
+                """.trimMargin(),
+
+                """
+                |fun f2() {
+                |    @Language("kotlin")
+                |    val code =
+                |        ""${'"'}
+                |            >@Suppress("diktat")
+                |            >fun foo() {
+                |            >    val a = 1
+                |            >}
+                |        ""${'"'} . trimMargin ( marginPrefix = ">" )
+                |    lintMethod(code)
+                |}
+                """.trimMargin(),
+
                 """
                 |fun checkScript() {
                 |    lintMethod(
@@ -193,6 +235,48 @@ internal interface IndentationRuleTestMixin {
                 |}
                 """.trimMargin(),
 
+                """
+                |fun f0() {
+                |    @Language("kotlin")
+                |    val code =
+                |            ""${'"'}
+                |                |@Suppress("diktat")
+                |                |fun foo() {
+                |                |    val a = 1
+                |                |}
+                |            ""${'"'}.trimMargin()
+                |    lintMethod(code)
+                |}
+                """.trimMargin(),
+
+                """
+                |fun f1() {
+                |    @Language("kotlin")
+                |    val code =
+                |            ""${'"'}
+                |                |@Suppress("diktat")
+                |                |fun foo() {
+                |                |    val a = 1
+                |                |}
+                |            ""${'"'}.trimMargin("|")
+                |    lintMethod(code)
+                |}
+                """.trimMargin(),
+
+                """
+                |fun f2() {
+                |    @Language("kotlin")
+                |    val code =
+                |            ""${'"'}
+                |                >@Suppress("diktat")
+                |                >fun foo() {
+                |                >    val a = 1
+                |                >}
+                |            ""${'"'} . trimMargin ( marginPrefix = ">" )
+                |    lintMethod(code)
+                |}
+                """.trimMargin(),
+
                 """
                 |fun checkScript() {
                 |    lintMethod(