Add test cases (#26)

* Add tests for the Exists function

* Add tests for the StripHTMLTags function

file/file_test.go

@@ -0,0 +1,43 @@
+package file
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/spf13/afero"
+)
+
+var FakeFs = afero.NewOsFs()
+
+func TestExists(t *testing.T) {
+	t.Run("expects file to exist", func(t *testing.T) {
+		input, _ := afero.TempFile(FakeFs, ".", "")
+		defer removeFile(input.Name(), t)
+
+		got := Exists(input.Name())
+		expect := true
+
+		if got != expect {
+			t.Errorf("Expected file %s to exist.", input.Name())
+		}
+	})
+
+	t.Run("expects file to not exist", func(t *testing.T) {
+		input := fmt.Sprintf("test_file_%d", time.Now().UnixNano())
+
+		got := Exists(input)
+		expect := false
+
+		if got != expect {
+			t.Errorf("Expected file %s to not exist", input)
+		}
+	})
+}
+
+func removeFile(name string, t *testing.T) {
+	err := FakeFs.Remove(name)
+	if err != nil {
+		t.Errorf("Did not cleanly delete file %s", name)
+	}
+}