Add tests for imagetools inspect

Signed-off-by: Laurent Goderre <laurent.goderre@docker.com>

util/imagetools/loader_test.go

@@ -0,0 +1,63 @@
+package imagetools
+
+import (
+	"encoding/base64"
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_scanSBOM(t *testing.T) {
+
+}
+
+func Test_scanProvenance(t *testing.T) {
+
+}
+
+func Test_isInTotoDSSE(t *testing.T) {
+	tests := []struct {
+		mime     string
+		expected bool
+	}{
+		{
+			mime:     "application/vnd.in-toto.spdx+dsse",
+			expected: true,
+		},
+		{
+			mime:     "application/vnd.in-toto.provenance+dsse",
+			expected: true,
+		},
+		{
+			mime:     "application/vnd.in-toto+json",
+			expected: false,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.mime, func(t *testing.T) {
+			assert.Equal(t, isInTotoDSSE(test.mime), test.expected)
+		})
+	}
+}
+
+func Test_decodeDSSE(t *testing.T) {
+	// Returns input when mime isn't a DSSE type
+	actual, err := decodeDSSE([]byte("foobar"), "application/vnd.in-toto+json")
+	assert.NoError(t, err)
+	assert.Equal(t, []byte("foobar"), actual)
+
+	// Returns the base64 decoded payload if is a DSSE
+	payload := base64.StdEncoding.EncodeToString([]byte("hello world"))
+	envelope := fmt.Sprintf("{\"payload\":\"%s\"}", payload)
+	actual, err = decodeDSSE([]byte(envelope), "application/vnd.in-toto.spdx+dsse")
+	assert.NoError(t, err)
+	assert.Equal(t, "hello world", string(actual))
+
+	actual, err = decodeDSSE([]byte("not a json"), "application/vnd.in-toto.spdx+dsse")
+	assert.Error(t, err)
+
+	actual, err = decodeDSSE([]byte("{\"payload\": \"not base64\"}"), "application/vnd.in-toto.spdx+dsse")
+	assert.Error(t, err)
+}