add tests around new file metadata cataloger

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

syft/file/digest_cataloger_test.go

@@ -0,0 +1,98 @@
+package file
+
+import (
+	"crypto"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/anchore/syft/syft/source"
+)
+
+func testDigests(t testing.TB, files []string, hashes ...crypto.Hash) map[source.Location][]Digest {
+	digests := make(map[source.Location][]Digest)
+
+	for _, f := range files {
+		fh, err := os.Open(f)
+		if err != nil {
+			t.Fatalf("could not open %q : %+v", f, err)
+		}
+		b, err := ioutil.ReadAll(fh)
+		if err != nil {
+			t.Fatalf("could not read %q : %+v", f, err)
+		}
+
+		for _, hash := range hashes {
+			h := hash.New()
+			h.Write(b)
+			digests[source.NewLocation(f)] = append(digests[source.NewLocation(f)], Digest{
+				Algorithm: cleanAlgorithmName(hash.String()),
+				Value:     fmt.Sprintf("%x", h.Sum(nil)),
+			})
+		}
+	}
+
+	return digests
+}
+
+func TestDigestsCataloger(t *testing.T) {
+	files := []string{"test-fixtures/last/path.txt", "test-fixtures/another-path.txt", "test-fixtures/a-path.txt"}
+
+	tests := []struct {
+		name           string
+		algorithms     []string
+		expected       map[source.Location][]Digest
+		constructorErr bool
+		catalogErr     bool
+	}{
+		{
+			name:           "bad algorithm",
+			algorithms:     []string{"sha-nothing"},
+			constructorErr: true,
+		},
+		{
+			name:           "unsupported algorithm",
+			algorithms:     []string{"sha512"},
+			constructorErr: true,
+		},
+		{
+			name:       "md5-sha1-sha256",
+			algorithms: []string{"md5"},
+			expected:   testDigests(t, files, crypto.MD5),
+		},
+		{
+			name:       "md5-sha1-sha256",
+			algorithms: []string{"md5", "sha1", "sha256"},
+			expected:   testDigests(t, files, crypto.MD5, crypto.SHA1, crypto.SHA256),
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			c, err := NewDigestsCataloger(test.algorithms)
+			if err != nil && !test.constructorErr {
+				t.Fatalf("could not create cataloger (but should have been able to): %+v", err)
+			} else if err == nil && test.constructorErr {
+				t.Fatalf("expected constructor error but did not get one")
+			} else if test.constructorErr && err != nil {
+				return
+			}
+
+			resolver := source.NewMockResolverForPaths(files...)
+			actual, err := c.Catalog(resolver)
+			if err != nil && !test.catalogErr {
+				t.Fatalf("could not catalog (but should have been able to): %+v", err)
+			} else if err == nil && test.catalogErr {
+				t.Fatalf("expected catalog error but did not get one")
+			} else if test.catalogErr && err != nil {
+				return
+			}
+
+			assert.Equal(t, actual, test.expected, "mismatched digests")
+
+		})
+	}
+}