feat: scan local go mod cache for licenses of golang packages (#1645)

Signed-off-by: Avi Deitcher <avi@deitcher.net>
Co-authored-by: Keith Zantow <kzantow@gmail.com>

syft/pkg/cataloger/golang/licenses_test.go

@@ -0,0 +1,76 @@
+package golang
+
+import (
+	"os"
+	"path"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/anchore/syft/syft/source"
+)
+
+func Test_LicenseSearch(t *testing.T) {
+	tests := []struct {
+		name     string
+		version  string
+		expected string
+	}{
+		{
+			name:     "github.com/someorg/somename",
+			version:  "v0.3.2",
+			expected: "Apache-2.0",
+		},
+		{
+			name:     "github.com/CapORG/CapProject",
+			version:  "v4.111.5",
+			expected: "MIT",
+		},
+	}
+
+	wd, err := os.Getwd()
+	require.NoError(t, err)
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			l := newGoLicenses(GoCatalogerOpts{
+				SearchLocalModCacheLicenses: true,
+				LocalModCacheDir:            path.Join(wd, "test-fixtures", "licenses"),
+			})
+			licenses, err := l.getLicenses(source.MockResolver{}, test.name, test.version)
+			require.NoError(t, err)
+
+			require.Len(t, licenses, 1)
+
+			require.Equal(t, test.expected, licenses[0])
+		})
+	}
+}
+
+func Test_processCaps(t *testing.T) {
+	tests := []struct {
+		name     string
+		expected string
+	}{
+		{
+			name:     "CycloneDX",
+			expected: "!cyclone!d!x",
+		},
+		{
+			name:     "Azure",
+			expected: "!azure",
+		},
+		{
+			name:     "xkcd",
+			expected: "xkcd",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			got := processCaps(test.name)
+
+			require.Equal(t, test.expected, got)
+		})
+	}
+}