feat: seclude formatParts util

format-parts.js

@@ -0,0 +1,20 @@
+// For given resolver returns
+
+"use strict";
+
+var ensureArray  = require("es5-ext/array/valid-array")
+  , isValue      = require("es5-ext/object/is-value")
+  , ensureObject = require("es5-ext/object/valid-object")
+  , ensureString = require("es5-ext/object/validate-stringifiable-value");
+
+module.exports = function (parts) {
+	var literals = ensureArray(ensureObject(parts).literals);
+	var substitutions = ensureArray(parts.substitutions);
+	var resolvedString = literals.length
+		? literals.reduce(function (resolved, literal, index) {
+				return resolved + substitutions[index - 1] + literal;
+		  })
+		: "";
+	if (isValue(parts.rest)) resolvedString += ensureString(parts.rest);
+	return resolvedString;
+};

index.js

@@ -1,20 +1,12 @@
 "use strict";
 
-var getPartsResolver = require("./get-parts-resolver");
+var getPartsResolver = require("./get-parts-resolver")
+  , formatParts      = require("./format-parts");
 
 module.exports = function (modifiers) {
 	var resolveParts = getPartsResolver(modifiers);
 
 	return function (formatIgnored/*, ...params*/) {
-		var data = resolveParts.apply(null, arguments);
-		var literals = data.literals;
-		var substitutions = data.substitutions;
-		var resolvedString = literals.length
-			? literals.reduce(function (resolved, literal, index) {
-					return resolved + substitutions[index - 1] + literal;
-			  })
-			: "";
-		if (data.rest) resolvedString += data.rest;
-		return resolvedString;
+		return formatParts(resolveParts.apply(null, arguments));
 	};
 };

test/format-parts.js

@@ -0,0 +1,37 @@
+"use strict";
+
+var test        = require("tape")
+  , formatParts = require("../format-parts");
+
+test("getResolver", function (t) {
+	t.test("Should resolve", function (t) {
+		t.equal(formatParts({ literals: ["foo raz"], substitutions: [], rest: null }), "foo raz");
+		t.equal(
+			formatParts({ literals: ["foo ", ""], substitutions: ["marko"], rest: null }),
+			"foo marko", "Single placeholder"
+		);
+		t.equal(
+			formatParts({
+				literals: ["foo ", " ", ""],
+				substitutions: ["marko", "12"],
+				rest: null
+			}),
+			"foo marko 12", "Two placeholders"
+		);
+		t.equal(
+			formatParts({ literals: [], substitutions: [], rest: null }), "",
+			"Non-string first argument without rest"
+		);
+
+		t.equal(
+			formatParts({ literals: ["foo ", ""], substitutions: ["marko"], rest: " 12-elo" }),
+			"foo marko 12-elo", "with rest handling"
+		);
+		t.equal(
+			formatParts({ literals: [], substitutions: [], rest: "12-13" }), "12-13",
+			"Non-string first argument with rest"
+		);
+		t.end();
+	});
+	t.end();
+});