working on test cases and dressing a bit of code

src/core/operations/ParseIMF.mjs

@@ -61,7 +61,7 @@ class ParseIMF extends Operation {
         const dataObj = eml.extractData(fields);
         let subject = null;
         const retval = [];
-        if (dataObj.length >= 1) {
+        if (dataObj.length) {
             subject = dataObj[0].fields.subject;
             if (dataObj[0].header) {
                 retval.push(new File([dataObj[0].header], "Header.txt", {type: "text/plain"}));

test/index.mjs

@@ -75,6 +75,7 @@ import "./tests/operations/ToGeohash.mjs";
 import "./tests/operations/TranslateDateTimeFormat";
 import "./tests/operations/Magic";
 import "./tests/operations/ParseTLV";
+import "./tests/operations/Mime";
 
 let allTestsPassing = true;
 const testStatusCounts = {

test/tests/operations/Mime.mjs

@@ -0,0 +1,23 @@
+/**
+ * Mime tests.
+ *
+ * @author bwhitn [brian.m.whitney@outlook.com]
+ * @copyright Crown Copyright 2018
+ * @license Apache-2.0
+ */
+import TestRegister from "../../TestRegister";
+
+TestRegister.addTests([
+    {
+        name: "Decode Mime Encoded Words",
+        input: "This is a GBK base64 encoded word: =?GBK?B?x/izx7ncvta52NPazfjC59Pfx+nQxc+i16g=?=.\nThis is a Cyrillic quoted word: =?utf-8?Q?=D0=A2=D0=B5=D1=81=D1=82_=D0=A2=D0=B5=D1=81=D1=82_=D0=A2=D0=B5=D1=81=D1=82?=.",
+        expectedOutput: ["This is a GBK base64 encoded word: 区城管局关于网络舆情信息专.",
+        "This is a Cyrillic quoted word: Тест Тест Тест."].join("\n"),
+        recipeConfig: [
+            {
+                "op": "Decode Mime Encoded Words",
+                "args": []
+            }
+        ]
+    },
+]);