Added test for rule disabling

ktlint-core/src/test/kotlin/com/pinterest/ktlint/core/DisabledRulesTest.kt

@@ -0,0 +1,68 @@
+package com.pinterest.ktlint.core
+
+import com.pinterest.ktlint.core.ast.ElementType
+import org.assertj.core.api.Assertions.assertThat
+import org.jetbrains.kotlin.com.intellij.lang.ASTNode
+import org.junit.Test
+import java.util.ArrayList
+
+class DisabledRulesTest {
+
+    @Test
+    fun testDisabledRule() {
+        class NoVarRule : Rule("no-var") {
+
+            override fun visit(
+                node: ASTNode,
+                autoCorrect: Boolean,
+                emit: (offset: Int, errorMessage: String, canBeAutoCorrected: Boolean) -> Unit
+            ) {
+                if (node.elementType == ElementType.VAR_KEYWORD) {
+                    emit(node.startOffset, "Unexpected var, use val instead", false)
+                }
+            }
+        }
+
+        assertThat(
+            ArrayList<LintError>().apply {
+                KtLint.lint(
+                    KtLint.Params(
+                        text = "var foo",
+                        ruleSets = listOf(RuleSet("standard", NoVarRule())),
+                        cb = { e, _ -> add(e) }
+                    )
+                )
+            }
+        ).isEqualTo(
+            listOf(
+                LintError(1, 1, "no-var", "Unexpected var, use val instead")
+            )
+        )
+
+        assertThat(
+            ArrayList<LintError>().apply {
+                KtLint.lint(
+                    KtLint.Params(
+                        text = "var foo",
+                        ruleSets = listOf(RuleSet("standard", NoVarRule())),
+                        cb = { e, _ -> add(e) },
+                        userData = mapOf(("disabled_rules" to "no-var"))
+                    )
+                )
+            }
+        ).isEmpty()
+
+        assertThat(
+            ArrayList<LintError>().apply {
+                KtLint.lint(
+                    KtLint.Params(
+                        text = "var foo",
+                        ruleSets = listOf(RuleSet("experimental", NoVarRule())),
+                        cb = { e, _ -> add(e) },
+                        userData = mapOf(("disabled_rules" to "experimental:no-var"))
+                    )
+                )
+            }
+        ).isEmpty()
+    }
+}