Repository: cqfn/diKTat (kotlin)

Issue:
Kdoc fixer false-negative: not generating a Kdoc for several public functions 
diktat 1.0.0-RC

```
    fun hasNoChildren() = children.size == 0
    fun getFirstChild() = children.elementAtOrNull(0)
```


```
/**
 * @return
 */
fun hasNoChildren() = children.size == 0
// <------ where is a Kdoc?
fun getFirstChild() = children.elementAtOrNull(0)
```

Pull request description:
### What's done:
* fixed bug in MISSING_KDOC_ON_FUNCTION
* We are changing criterion for getters and setters. This is single line body function with element type CALL_EXPRESSION фтв REFERENCE_EXPRESSION or DOT_QUALIFIED_EXPRESSION with keyword _this_
Closes #965

Patch:
diff --git a/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/chapter2/comments/HeaderCommentRule.kt b/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/chapter2/comments/HeaderCommentRule.kt
index 00bf45c70a..cf26f22114 100644
--- a/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/chapter2/comments/HeaderCommentRule.kt
+++ b/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/chapter2/comments/HeaderCommentRule.kt
@@ -225,6 +225,8 @@ class HeaderCommentRule(configRules: List<RulesConfig>) : DiktatRule(
 
         /**
          * Whether copyright text is present in the configuration
+         *
+         * @return true if config has "copyrightText"
          */
         internal fun hasCopyrightText() = config.keys.contains("copyrightText")
 
diff --git a/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/chapter2/kdoc/KdocMethods.kt b/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/chapter2/kdoc/KdocMethods.kt
index a41fdb5752..363dfa1ae3 100644
--- a/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/chapter2/kdoc/KdocMethods.kt
+++ b/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/chapter2/kdoc/KdocMethods.kt
@@ -29,30 +29,29 @@ import org.cqfn.diktat.ruleset.utils.kDocTags
 import org.cqfn.diktat.ruleset.utils.parameterNames
 import org.cqfn.diktat.ruleset.utils.splitPathToDirs
 
-import com.pinterest.ktlint.core.ast.ElementType.BINARY_EXPRESSION
+import com.pinterest.ktlint.core.ast.ElementType
 import com.pinterest.ktlint.core.ast.ElementType.BLOCK
-import com.pinterest.ktlint.core.ast.ElementType.CALLABLE_REFERENCE_EXPRESSION
 import com.pinterest.ktlint.core.ast.ElementType.CALL_EXPRESSION
-import com.pinterest.ktlint.core.ast.ElementType.COLLECTION_LITERAL_EXPRESSION
 import com.pinterest.ktlint.core.ast.ElementType.COLON
+import com.pinterest.ktlint.core.ast.ElementType.DOT_QUALIFIED_EXPRESSION
+import com.pinterest.ktlint.core.ast.ElementType.EQ
 import com.pinterest.ktlint.core.ast.ElementType.FUN
 import com.pinterest.ktlint.core.ast.ElementType.KDOC
 import com.pinterest.ktlint.core.ast.ElementType.KDOC_SECTION
 import com.pinterest.ktlint.core.ast.ElementType.KDOC_TAG_NAME
 import com.pinterest.ktlint.core.ast.ElementType.KDOC_TEXT
-import com.pinterest.ktlint.core.ast.ElementType.LAMBDA_EXPRESSION
 import com.pinterest.ktlint.core.ast.ElementType.MODIFIER_LIST
 import com.pinterest.ktlint.core.ast.ElementType.REFERENCE_EXPRESSION
-import com.pinterest.ktlint.core.ast.ElementType.SAFE_ACCESS_EXPRESSION
+import com.pinterest.ktlint.core.ast.ElementType.THIS_EXPRESSION
 import com.pinterest.ktlint.core.ast.ElementType.THROW
 import com.pinterest.ktlint.core.ast.ElementType.TYPE_REFERENCE
-import com.pinterest.ktlint.core.ast.ElementType.WHEN_CONDITION_WITH_EXPRESSION
 import org.jetbrains.kotlin.com.intellij.lang.ASTNode
 import org.jetbrains.kotlin.com.intellij.psi.impl.source.tree.LeafPsiElement
 import org.jetbrains.kotlin.com.intellij.psi.impl.source.tree.PsiWhiteSpaceImpl
 import org.jetbrains.kotlin.com.intellij.psi.tree.TokenSet
 import org.jetbrains.kotlin.kdoc.parser.KDocKnownTag
 import org.jetbrains.kotlin.kdoc.psi.impl.KDocTag
+import org.jetbrains.kotlin.psi.KtDotQualifiedExpression
 import org.jetbrains.kotlin.psi.KtThrowExpression
 import org.jetbrains.kotlin.psi.psiUtil.referenceExpression
 
@@ -143,11 +142,12 @@ class KdocMethods(configRules: List<RulesConfig>) : DiktatRule(
         }
 
         val explicitReturnType = node.findChildAfter(COLON, TYPE_REFERENCE)
+        val hasNotExpressionBodyTypes = allExpressionBodyTypes.any { node.hasChildOfType(it) }
         val hasExplicitNotUnitReturnType = explicitReturnType != null && explicitReturnType.text != "Unit"
         val hasExplicitUnitReturnType = explicitReturnType != null && explicitReturnType.text == "Unit"
-        val isFunWithExpressionBody = expressionBodyTypes.any { node.hasChildOfType(it) }
+        val isFunWithExpressionBody = node.hasChildOfType(EQ)
         val hasReturnKdoc = kdocTags != null && kdocTags.hasKnownKdocTag(KDocKnownTag.RETURN)
-        return (hasExplicitNotUnitReturnType || isFunWithExpressionBody && !hasExplicitUnitReturnType) && !hasReturnKdoc
+        return (hasExplicitNotUnitReturnType || isFunWithExpressionBody && !hasExplicitUnitReturnType && hasNotExpressionBodyTypes) && !hasReturnKdoc
     }
 
     private fun getExplicitlyThrownExceptions(node: ASTNode): Set<String> {
@@ -251,12 +251,26 @@ class KdocMethods(configRules: List<RulesConfig>) : DiktatRule(
         }
     }
 
-    private fun ASTNode.isSingleLineGetterOrSetter() = isGetterOrSetter() && (expressionBodyTypes.any { hasChildOfType(it) } || getBodyLines().size == 1)
+    private fun ASTNode.isSingleLineGetterOrSetter(): Boolean {
+        val dotQualifiedExp = this.findChildByType(DOT_QUALIFIED_EXPRESSION)?.psi?.let { it as KtDotQualifiedExpression }
+        val isThisExpression = dotQualifiedExp != null && dotQualifiedExp.receiverExpression.node.elementType == THIS_EXPRESSION
+        val isExpressionBodyTypes = expressionBodyTypes.any { hasChildOfType(it) }
+        return isGetterOrSetter() && (isExpressionBodyTypes || getBodyLines().size == 1 || isThisExpression)
+    }
 
     companion object {
-        // expression body of function can have a lot of 'ElementType's, this list might be not full
-        private val expressionBodyTypes = setOf(BINARY_EXPRESSION, CALL_EXPRESSION, LAMBDA_EXPRESSION, REFERENCE_EXPRESSION,
-            CALLABLE_REFERENCE_EXPRESSION, SAFE_ACCESS_EXPRESSION, WHEN_CONDITION_WITH_EXPRESSION, COLLECTION_LITERAL_EXPRESSION)
+        private val expressionBodyTypes = setOf(CALL_EXPRESSION, REFERENCE_EXPRESSION)
+        private val allExpressionBodyTypes = setOf(
+            DOT_QUALIFIED_EXPRESSION,
+            CALL_EXPRESSION,
+            REFERENCE_EXPRESSION,
+            ElementType.BINARY_EXPRESSION,
+            ElementType.LAMBDA_EXPRESSION,
+            ElementType.CALLABLE_REFERENCE_EXPRESSION,
+            ElementType.SAFE_ACCESS_EXPRESSION,
+            ElementType.WHEN_CONDITION_WITH_EXPRESSION,
+            ElementType.COLLECTION_LITERAL_EXPRESSION
+        )
         private val uselessKdocRegex = """^([rR]eturn|[gGsS]et)[s]?\s+\w+(\s+\w+)?$""".toRegex()
     }
 }
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 a2a634eebf..5d976b27d8 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
@@ -303,6 +303,7 @@ class IndentationRule(configRules: List<RulesConfig>) : DiktatRule(
 
         /**
          * @param token a token that caused indentation increment, for example an opening brace
+         * @return Unit
          */
         fun storeIncrementingToken(token: IElementType) = token
             .also { require(it in increasingTokens) { "Only tokens that increase indentation should be passed to this method" } }
@@ -342,6 +343,7 @@ class IndentationRule(configRules: List<RulesConfig>) : DiktatRule(
          * @param initiator a node that caused exceptional indentation
          * @param indent an additional indent
          * @param includeLastChild whether the last child node should be included in the range affected by exceptional indentation
+         * @return true if add exception in exceptionalIndents
          */
         fun addException(
             initiator: ASTNode,
@@ -351,6 +353,7 @@ class IndentationRule(configRules: List<RulesConfig>) : DiktatRule(
 
         /**
          * @param astNode the node which is used to determine whether exceptinoal indents are still active
+         * @return boolean result
          */
         fun checkAndReset(astNode: ASTNode) = exceptionalIndents.retainAll { it.isActive(astNode) }
 
diff --git a/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/utils/KotlinParser.kt b/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/utils/KotlinParser.kt
index 44a01a6e20..9307619f1c 100644
--- a/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/utils/KotlinParser.kt
+++ b/diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/utils/KotlinParser.kt
@@ -76,6 +76,7 @@ class KotlinParser {
 
     /**
      * @param text kotlin code
+     * @return [KtPrimaryConstructor]
      */
     fun createPrimaryConstructor(text: String) = ktPsiFactory.createPrimaryConstructor(text)
 


Test patch:
diff --git a/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter2/KdocMethodsFixTest.kt b/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter2/KdocMethodsFixTest.kt
index ae8a5074c9..6fe6014cef 100644
--- a/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter2/KdocMethodsFixTest.kt
+++ b/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter2/KdocMethodsFixTest.kt
@@ -22,6 +22,12 @@ class KdocMethodsFixTest : FixTestBase("test/paragraph2/kdoc/package/src/main/ko
         fixAndCompare("MissingKdocWithModifiersExpected.kt", "MissingKdocWithModifiersTest.kt")
     }
 
+    @Test
+    @Tag(WarningNames.MISSING_KDOC_ON_FUNCTION)
+    fun `KDoc should be for function with single line body`() {
+        fixAndCompare("MissingKdocOnFunctionExpected.kt", "MissingKdocOnFunctionTest.kt")
+    }
+
     @Test
     @Tag(WarningNames.KDOC_EMPTY_KDOC)
     fun `Rule should not suggest empty KDoc templates`() {
diff --git a/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter2/KdocMethodsTest.kt b/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter2/KdocMethodsTest.kt
index 9002b23029..59b26ad742 100644
--- a/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter2/KdocMethodsTest.kt
+++ b/diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter2/KdocMethodsTest.kt
@@ -292,7 +292,7 @@ class KdocMethodsTest : LintTestBase(::KdocMethods) {
                     |        this.x = x
                     |    }
                     |    
-                    |    fun getX() {
+                    |    fun getX(): Type {
                     |        return x
                     |    }
                     |    
@@ -309,7 +309,6 @@ class KdocMethodsTest : LintTestBase(::KdocMethods) {
                     |    }
                     |}
                 """.trimMargin(),
-            LintError(10, 5, ruleId, "${MISSING_KDOC_ON_FUNCTION.warnText()} getY", false),
             LintError(12, 5, ruleId, "${MISSING_KDOC_ON_FUNCTION.warnText()} setY", true),
             LintError(17, 5, ruleId, "${MISSING_KDOC_ON_FUNCTION.warnText()} getZ", true)
         )
@@ -368,4 +367,17 @@ class KdocMethodsTest : LintTestBase(::KdocMethods) {
             LintError(1, 1, ruleId, "${MISSING_KDOC_ON_FUNCTION.warnText()} foo", true)
         )
     }
+
+    @Test
+    @Tag(WarningNames.MISSING_KDOC_ON_FUNCTION)
+    fun `KDoc should be for function with single line body`() {
+        lintMethod(
+            """
+                    |fun hasNoChildren() = children.size == 0
+                    |fun getFirstChild() = children.elementAtOrNull(0)
+                """.trimMargin(),
+            LintError(1, 1, ruleId, "${MISSING_KDOC_ON_FUNCTION.warnText()} hasNoChildren", true),
+            LintError(2, 1, ruleId, "${MISSING_KDOC_ON_FUNCTION.warnText()} getFirstChild", true)
+        )
+    }
 }
diff --git a/diktat-rules/src/test/resources/test/paragraph2/kdoc/package/src/main/kotlin/org/cqfn/diktat/kdoc/methods/MissingKdocOnFunctionExpected.kt b/diktat-rules/src/test/resources/test/paragraph2/kdoc/package/src/main/kotlin/org/cqfn/diktat/kdoc/methods/MissingKdocOnFunctionExpected.kt
new file mode 100644
index 0000000000..db817c5226
--- /dev/null
+++ b/diktat-rules/src/test/resources/test/paragraph2/kdoc/package/src/main/kotlin/org/cqfn/diktat/kdoc/methods/MissingKdocOnFunctionExpected.kt
@@ -0,0 +1,13 @@
+package test.paragraph2.kdoc
+
+class Example {
+    /**
+ * @return
+ */
+fun hasNoChildren() = children.size == 0
+
+    /**
+ * @return
+ */
+fun getFirstChild() = children.elementAtOrNull(0)
+}
\ No newline at end of file
diff --git a/diktat-rules/src/test/resources/test/paragraph2/kdoc/package/src/main/kotlin/org/cqfn/diktat/kdoc/methods/MissingKdocOnFunctionTest.kt b/diktat-rules/src/test/resources/test/paragraph2/kdoc/package/src/main/kotlin/org/cqfn/diktat/kdoc/methods/MissingKdocOnFunctionTest.kt
new file mode 100644
index 0000000000..b782d8cb1a
--- /dev/null
+++ b/diktat-rules/src/test/resources/test/paragraph2/kdoc/package/src/main/kotlin/org/cqfn/diktat/kdoc/methods/MissingKdocOnFunctionTest.kt
@@ -0,0 +1,7 @@
+package test.paragraph2.kdoc
+
+class Example {
+    fun hasNoChildren() = children.size == 0
+
+    fun getFirstChild() = children.elementAtOrNull(0)
+}
\ No newline at end of file
diff --git a/diktat-test-framework/src/main/kotlin/org/cqfn/diktat/test/framework/config/TestArgumentsReader.kt b/diktat-test-framework/src/main/kotlin/org/cqfn/diktat/test/framework/config/TestArgumentsReader.kt
index 6e387548b7..22b2dd768c 100644
--- a/diktat-test-framework/src/main/kotlin/org/cqfn/diktat/test/framework/config/TestArgumentsReader.kt
+++ b/diktat-test-framework/src/main/kotlin/org/cqfn/diktat/test/framework/config/TestArgumentsReader.kt
@@ -74,6 +74,8 @@ class TestArgumentsReader(
 
     /**
      * Whether all tests should be run
+     *
+     * @return true if command has option "all"
      */
     fun shouldRunAllTests() = cmd.hasOption("all")
 
diff --git a/diktat-test-framework/src/main/kotlin/org/cqfn/diktat/test/framework/processing/TestCompare.kt b/diktat-test-framework/src/main/kotlin/org/cqfn/diktat/test/framework/processing/TestCompare.kt
index 5446b992e9..e37ce0879d 100644
--- a/diktat-test-framework/src/main/kotlin/org/cqfn/diktat/test/framework/processing/TestCompare.kt
+++ b/diktat-test-framework/src/main/kotlin/org/cqfn/diktat/test/framework/processing/TestCompare.kt
@@ -88,6 +88,8 @@ open class TestCompare : TestBase {
 
     /**
      * Get result of the test execution
+     *
+     * @return list stdOut
      */
     protected open fun getExecutionResult() = testResult.stdOut
 }