Add first simple unit test with workflow (#81)

* Adding first simple unit test

* Add test run to workflow

Co-authored-by: Sascha L. Teichmann <sascha.teichmann@intevation.de>

.github/workflows/go.yml

@@ -29,3 +29,6 @@ jobs:
 
       - name: golint
         uses: Jerome1337/golint-action@v1.0.2
+
+      - name: Tests
+        run: go test -v ./..

util/file_test.go

@@ -0,0 +1,30 @@
+package util
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestNWriter(t *testing.T) {
+
+	msg := []byte("Gruß!\n")
+
+	first, second := msg[:len(msg)/2], msg[len(msg)/2:]
+
+	var buf bytes.Buffer
+	nw := NWriter{Writer: &buf, N: 0}
+	_, err1 := nw.Write(first)
+	_, err2 := nw.Write(second)
+
+	if err1 != nil || err2 != nil {
+		t.Error("Calling NWriter failed")
+	}
+
+	if n := int64(len(msg)); nw.N != n {
+		t.Errorf("Expected %d bytes, but counted %d", n, nw.N)
+	}
+
+	if out := buf.Bytes(); !bytes.Equal(msg, out) {
+		t.Errorf("Expected %q, but got %q", msg, out)
+	}
+}