test: add select subroutine tests

test/surgeon/subroutines/selectSubroutine.js

@@ -0,0 +1,51 @@
+import test from 'ava';
+import sinon from 'sinon';
+import selectSubroutine from '../../../src/subroutines/selectSubroutine';
+
+test('returns array when expecting multiple results', (t): void => {
+  const isElement = sinon.stub().returns(true);
+  const querySelectorAll = sinon.stub().returns(['foo', 'bar']);
+
+  const results = selectSubroutine({
+    isElement,
+    querySelectorAll
+  }, null, ['.foo', '{0,}']);
+
+  t.deepEqual(results, ['foo', 'bar']);
+});
+
+test('returns a single result when expecting at most 1 result', (t): void => {
+  const isElement = sinon.stub().returns(true);
+  const querySelectorAll = sinon.stub().returns(['foo']);
+
+  const result = selectSubroutine({
+    isElement,
+    querySelectorAll
+  }, null, ['.foo', '{0,1}']);
+
+  t.true(result === 'foo');
+});
+
+test('returns an empty array when expecting multiple results', (t): void => {
+  const isElement = sinon.stub().returns(true);
+  const querySelectorAll = sinon.stub().returns([]);
+
+  const results = selectSubroutine({
+    isElement,
+    querySelectorAll
+  }, null, ['.foo', '{0,}']);
+
+  t.deepEqual(results, []);
+});
+
+test('returns null when expecting at most 1 result', (t): void => {
+  const isElement = sinon.stub().returns(true);
+  const querySelectorAll = sinon.stub().returns([]);
+
+  const result = selectSubroutine({
+    isElement,
+    querySelectorAll
+  }, null, ['.foo', '{0,1}']);
+
+  t.true(result === null);
+});