diff --git a/src/checkAutoItCode.js b/src/checkAutoItCode.js
deleted file mode 100644
index 6a5b6f8..0000000
--- a/src/checkAutoItCode.js
+++ /dev/null
@@ -1,36 +0,0 @@
-// const configuration = workspace.getConfiguration('autoit');
-// const { checkPath } = configuration;
-import { Diagnostic, DiagnosticSeverity, Range, Position } from 'vscode';
-
-export const getDiagnosticSeverity = severityString => {
-  switch (severityString) {
-    case 'warning':
-      return DiagnosticSeverity.Warning;
-    default:
-      return DiagnosticSeverity.Error;
-  }
-};
-
-export const getDiagnosticRange = (line, position) => {
-  const diagnosticPosition = new Position(parseInt(line, 10) - 1, parseInt(position, 10) - 1);
-
-  return new Range(diagnosticPosition, diagnosticPosition);
-};
-
-export const updateDiagnostics = (currentDiagnostics, scriptPath, range, description, severity) => {
-  const diagnosticToAdd = new Diagnostic(range, description, severity);
-  const updatedDiagnostics = currentDiagnostics;
-
-  if (!(scriptPath in updatedDiagnostics)) {
-    updatedDiagnostics[scriptPath] = [];
-  }
-  updatedDiagnostics[scriptPath].push(diagnosticToAdd);
-
-  return updatedDiagnostics;
-};
-
-const checkAutoItCode = () => {
-  return null;
-};
-
-export default checkAutoItCode;
diff --git a/src/diagnosticUtils.js b/src/diagnosticUtils.js
new file mode 100644
index 0000000..d54fd9f
--- /dev/null
+++ b/src/diagnosticUtils.js
@@ -0,0 +1,63 @@
+import { Diagnostic, DiagnosticSeverity, Range, Position, Uri } from 'vscode';
+
+export const getDiagnosticSeverity = severityString => {
+  switch (severityString) {
+    case 'warning':
+      return DiagnosticSeverity.Warning;
+    default:
+      return DiagnosticSeverity.Error;
+  }
+};
+
+export const getDiagnosticRange = (line, position) => {
+  const diagnosticPosition = new Position(parseInt(line, 10) - 1, parseInt(position, 10) - 1);
+
+  return new Range(diagnosticPosition, diagnosticPosition);
+};
+
+export const updateDiagnostics = (currentDiagnostics, scriptPath, range, description, severity) => {
+  const diagnosticToAdd = new Diagnostic(range, description, severity);
+  const updatedDiagnostics = currentDiagnostics;
+
+  if (!(scriptPath in updatedDiagnostics)) {
+    updatedDiagnostics[scriptPath] = [];
+  }
+  updatedDiagnostics[scriptPath].push(diagnosticToAdd);
+
+  return updatedDiagnostics;
+};
+
+/**
+ * Processes the results of AU3Check, identifies warnings and errors.
+ * @param {string} output Text returned from AU3Check.
+ * @param {vscode.DiagnosticCollection} collection - The diagnostic collection to update.
+ */
+export const parseAu3CheckOutput = (output, collection) => {
+  const OUTPUT_REGEXP = /"(?<scriptPath>.+)"\((?<line>\d{1,4}),(?<position>\d{1,4})\)\s:\s(?<severity>warning|error):\s(?<description>.+)\./gm;
+  let matches = null;
+  let diagnosticRange;
+  let diagnosticSeverity;
+  let diagnostics = {};
+
+  matches = OUTPUT_REGEXP.exec(output);
+  while (matches !== null) {
+    diagnosticRange = getDiagnosticRange(matches.groups.line, matches.groups.position);
+    diagnosticSeverity = getDiagnosticSeverity(matches.groups.severity);
+
+    diagnostics = updateDiagnostics(
+      diagnostics,
+      matches.groups.scriptPath,
+      diagnosticRange,
+      matches.groups.description,
+      diagnosticSeverity,
+    );
+
+    matches = OUTPUT_REGEXP.exec(output);
+  }
+
+  Object.keys(diagnostics).forEach(scriptPath => {
+    collection.set(Uri.file(scriptPath), diagnostics[scriptPath]);
+  });
+};
+
+export default parseAu3CheckOutput;
diff --git a/src/extension.js b/src/extension.js
index d90c65a..05d4aa2 100644
--- a/src/extension.js
+++ b/src/extension.js
@@ -11,43 +11,11 @@ const workspaceSymbolsFeature = require('./ai_workspaceSymbols');
 const goToDefinitionFeature = require('./ai_definition');
 
 const { registerCommands } = require('./registerCommands');
-const {
-  getDiagnosticRange,
-  getDiagnosticSeverity,
-  updateDiagnostics,
-} = require('./checkAutoItCode');
+const { parseAu3CheckOutput } = require('./diagnosticUtils');
 
 let diagnosticCollection;
 
-const parseAu3CheckOutput = (document, output) => {
-  const OUTPUT_REGEXP = /"(?<scriptPath>.+)"\((?<line>\d{1,4}),(?<position>\d{1,4})\)\s:\s(?<severity>warning|error):\s(?<description>.+)\./gm;
-  let matches = null;
-  let diagnosticRange;
-  let diagnosticSeverity;
-  let diagnostics = {};
-
-  matches = OUTPUT_REGEXP.exec(output);
-  while (matches !== null) {
-    diagnosticRange = getDiagnosticRange(matches.groups.line, matches.groups.position);
-    diagnosticSeverity = getDiagnosticSeverity(matches.groups.severity);
-
-    diagnostics = updateDiagnostics(
-      diagnostics,
-      matches.groups.scriptPath,
-      diagnosticRange,
-      matches.groups.description,
-      diagnosticSeverity,
-    );
-
-    matches = OUTPUT_REGEXP.exec(output);
-  }
-
-  Object.keys(diagnostics).forEach(scriptPath => {
-    diagnosticCollection.set(vscode.Uri.file(scriptPath), diagnostics[scriptPath]);
-  });
-};
-
-function checkAutoItCode(document) {
+const checkAutoItCode = document => {
   const { checkPath, enableDiagnostics } = vscode.workspace.getConfiguration('autoit');
 
   diagnosticCollection.clear();
@@ -75,13 +43,13 @@ function checkAutoItCode(document) {
     if (data.length === 0) {
       return;
     }
-    parseAu3CheckOutput(document, data.toString());
+    parseAu3CheckOutput(data.toString(), diagnosticCollection);
   });
 
   checkProcess.stderr.on('error', error => {
     vscode.window.showErrorMessage(`${checkPath} error: ${error}`);
   });
-}
+};
 
 const activate = ctx => {
   const features = [