Add test for job using struct field

driver_test.go

@@ -162,3 +162,58 @@ func TestLocalNoCrashOnNoResolvedInputFiles(t *testing.T) {
 
 	driver.Main()
 }
+
+type statefulJob struct {
+	filterWords *[]string
+}
+
+func (s statefulJob) Map(key, value string, emitter Emitter) {
+	for _, word := range strings.Fields(value) {
+		for _, filterWord := range *s.filterWords {
+			if filterWord == word {
+				emitter.Emit(word, "1")
+			}
+		}
+	}
+}
+
+func (statefulJob) Reduce(key string, values ValueIterator, emitter Emitter) {
+	count := 0
+	for range values.Iter() {
+		count++
+	}
+	emitter.Emit(key, fmt.Sprintf("%d", count))
+}
+
+func TestLocalStructFieldMapReduce(t *testing.T) {
+	tmpdir, err := ioutil.TempDir("", "test")
+	assert.Nil(t, err)
+	defer os.RemoveAll(tmpdir)
+
+	inputPath := filepath.Join(tmpdir, "test_input")
+	ioutil.WriteFile(inputPath, []byte("the test input\nthe input test\nfoo bar baz"), 0700)
+
+	jobStruct := statefulJob{filterWords: &[]string{"foo", "bar"}}
+	job := NewJob(jobStruct, jobStruct)
+	driver := NewDriver(
+		job,
+		WithInputs(tmpdir),
+		WithWorkingLocation(tmpdir),
+	)
+
+	driver.Main()
+
+	output, err := ioutil.ReadFile(filepath.Join(tmpdir, "output-part-0"))
+	assert.Nil(t, err)
+
+	keyVals := testOutputToKeyValues(string(output))
+	assert.Len(t, keyVals, 2)
+
+	correct := []keyValue{
+		{"foo", "1"},
+		{"bar", "1"},
+	}
+	for _, kv := range correct {
+		assert.Contains(t, keyVals, kv)
+	}
+}