Fix: improve newline-per-chained-call message (fixes #6340)

lib/rules/newline-per-chained-call.js

@@ -38,6 +38,21 @@ module.exports = {
 
         var sourceCode = context.getSourceCode();
 
+        /**
+         * Gets the property text of a given MemberExpression node.
+         * If the text is multiline, this returns only the first line.
+         *
+         * @param {ASTNode} node - A MemberExpression node to get.
+         * @returns {string} The property text of the node.
+         */
+        function getPropertyText(node) {
+            var prefix = node.computed ? "[" : ".";
+            var lines = sourceCode.getText(node.property).split(/\r\n|\r|\n/g);
+            var suffix = node.computed && lines.length === 1 ? "]" : "";
+
+            return prefix + lines[0] + suffix;
+        }
+
         return {
             "CallExpression:exit": function(node) {
                 if (!node.callee || node.callee.type !== "MemberExpression") {
@@ -57,7 +72,7 @@ module.exports = {
                     context.report(
                         callee.property,
                         callee.property.loc.start,
-                        "Expected line break after `" + sourceCode.getText(callee.object).replace(/\r\n|\r|\n/g, "\\n") + "`."
+                        "Expected line break before `" + getPropertyText(callee) + "`."
                     );
                 }
             }

tests/lib/rules/newline-per-chained-call.js

@@ -53,56 +53,97 @@ ruleTester.run("newline-per-chained-call", rule, {
     invalid: [{
         code: "_\n.chain({}).map(foo).filter(bar).value();",
         errors: [{
-            message: "Expected line break after `_\\n.chain({}).map(foo)`."
+            message: "Expected line break before `.filter`."
         }, {
-            message: "Expected line break after `_\\n.chain({}).map(foo).filter(bar)`."
+            message: "Expected line break before `.value`."
         }]
     }, {
         code: "_\n.chain({})\n.map(foo)\n.filter(bar).value();",
         errors: [{
-            message: "Expected line break after `_\\n.chain({})\\n.map(foo)\\n.filter(bar)`."
+            message: "Expected line break before `.value`."
         }]
     }, {
         code: "a().b().c().e.d()",
         errors: [{
-            message: "Expected line break after `a().b()`."
-        }]
-    }, {
-        code: "a().b().c().e.d()",
-        errors: [{
-            message: "Expected line break after `a().b()`."
+            message: "Expected line break before `.c`."
         }]
     }, {
         code: "a.b.c().e().d()",
         errors: [{
-            message: "Expected line break after `a.b.c().e()`."
+            message: "Expected line break before `.d`."
         }]
     }, {
         code: "_.chain({}).map(a).value(); ",
         errors: [{
-            message: "Expected line break after `_.chain({}).map(a)`."
+            message: "Expected line break before `.value`."
         }]
     }, {
         code: "var a = m1.m2();\n var b = m1.m2().m3().m4().m5();",
         errors: [{
-            message: "Expected line break after `m1.m2().m3()`."
+            message: "Expected line break before `.m4`."
         }, {
-            message: "Expected line break after `m1.m2().m3().m4()`."
+            message: "Expected line break before `.m5`."
         }]
     }, {
         code: "var a = m1.m2();\n var b = m1.m2().m3()\n.m4().m5();",
         errors: [{
-            message: "Expected line break after `m1.m2().m3()\\n.m4()`."
+            message: "Expected line break before `.m5`."
         }]
     }, {
         code: "var a = m1().m2\n.m3().m4().m5().m6().m7();",
         options: [{
             ignoreChainWithDepth: 3
         }],
         errors: [{
-            message: "Expected line break after `m1().m2\\n.m3().m4().m5()`."
+            message: "Expected line break before `.m6`."
+        }, {
+            message: "Expected line break before `.m7`."
+        }]
+    }, {
+        code: [
+            "http.request({",
+            "    // Param",
+            "    // Param",
+            "    // Param",
+            "}).on('response', function(response) {",
+            "    // Do something with response.",
+            "    // Do something with response.",
+            "    // Do something with response.",
+            "    // Do something with response.",
+            "    // Do something with response.",
+            "    // Do something with response.",
+            "    // Do something with response.",
+            "    // Do something with response.",
+            "    // Do something with response.",
+            "    // Do something with response.",
+            "}).on('error', function(error) {",
+            "    // Do something with error.",
+            "    // Do something with error.",
+            "    // Do something with error.",
+            "    // Do something with error.",
+            "    // Do something with error.",
+            "    // Do something with error.",
+            "    // Do something with error.",
+            "    // Do something with error.",
+            "    // Do something with error.",
+            "    // Do something with error.",
+            "}).end();"
+        ].join("\n"),
+        errors: [{
+            message: "Expected line break before `.on`."
+        }, {
+            message: "Expected line break before `.end`."
+        }]
+    }, {
+        code: [
+            "anObject.method1().method2()['method' + n]()[aCondition ?",
+            "    'method3' :",
+            "    'method4']()"
+        ].join("\n"),
+        errors: [{
+            message: "Expected line break before `['method' + n]`."
         }, {
-            message: "Expected line break after `m1().m2\\n.m3().m4().m5().m6()`."
+            message: "Expected line break before `[aCondition ?`."
         }]
     }]