Add coverage on pkg/archive

Add tests on:
- changes.go
- archive.go
- wrap.go

Should fix #11603 as the coverage is now 81.2% on the ``pkg/archive``
package. There is still room for improvement though :).

Signed-off-by: Vincent Demeester <vincent@sbr.pm>

archive/wrap_test.go

@@ -0,0 +1,98 @@
+package archive
+
+import (
+	"archive/tar"
+	"bytes"
+	"io"
+	"testing"
+)
+
+func TestGenerateEmptyFile(t *testing.T) {
+	archive, err := Generate("emptyFile")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if archive == nil {
+		t.Fatal("The generated archive should not be nil.")
+	}
+
+	expectedFiles := [][]string{
+		{"emptyFile", ""},
+	}
+
+	tr := tar.NewReader(archive)
+	actualFiles := make([][]string, 0, 10)
+	i := 0
+	for {
+		hdr, err := tr.Next()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			t.Fatal(err)
+		}
+		buf := new(bytes.Buffer)
+		buf.ReadFrom(tr)
+		content := buf.String()
+		actualFiles = append(actualFiles, []string{hdr.Name, content})
+		i++
+	}
+	if len(actualFiles) != len(expectedFiles) {
+		t.Fatalf("Number of expected file %d, got %d.", len(expectedFiles), len(actualFiles))
+	}
+	for i := 0; i < len(expectedFiles); i++ {
+		actual := actualFiles[i]
+		expected := expectedFiles[i]
+		if actual[0] != expected[0] {
+			t.Fatalf("Expected name '%s', Actual name '%s'", expected[0], actual[0])
+		}
+		if actual[1] != expected[1] {
+			t.Fatalf("Expected content '%s', Actual content '%s'", expected[1], actual[1])
+		}
+	}
+}
+
+func TestGenerateWithContent(t *testing.T) {
+	archive, err := Generate("file", "content")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if archive == nil {
+		t.Fatal("The generated archive should not be nil.")
+	}
+
+	expectedFiles := [][]string{
+		{"file", "content"},
+	}
+
+	tr := tar.NewReader(archive)
+	actualFiles := make([][]string, 0, 10)
+	i := 0
+	for {
+		hdr, err := tr.Next()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			t.Fatal(err)
+		}
+		buf := new(bytes.Buffer)
+		buf.ReadFrom(tr)
+		content := buf.String()
+		actualFiles = append(actualFiles, []string{hdr.Name, content})
+		i++
+	}
+	if len(actualFiles) != len(expectedFiles) {
+		t.Fatalf("Number of expected file %d, got %d.", len(expectedFiles), len(actualFiles))
+	}
+	for i := 0; i < len(expectedFiles); i++ {
+		actual := actualFiles[i]
+		expected := expectedFiles[i]
+		if actual[0] != expected[0] {
+			t.Fatalf("Expected name '%s', Actual name '%s'", expected[0], actual[0])
+		}
+		if actual[1] != expected[1] {
+			t.Fatalf("Expected content '%s', Actual content '%s'", expected[1], actual[1])
+		}
+	}
+}