internal/postgres: update definition of latest

The definition of latest is updated to prefer incompatible
release/prerelease versions over pseudoversion. This matches the
definition by cmd/go.

Change-Id: Ic3c79c32e14dc4df3cf11d52df6548f0fd781a6b
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/259997
Trust: Julie Qiu <julie@golang.org>
Run-TryBot: Julie Qiu <julie@golang.org>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>

1 files changed, 45 insertions, 0 deletions

diff --git a/internal/postgres/insert_module_test.go b/internal/postgres/insert_module_test.go
index 6a1dd4af..e1652f78 100644
--- a/internal/postgres/insert_module_test.go
+++ b/internal/postgres/insert_module_test.go
@@ -394,6 +394,51 @@ func TestLatestVersion(t *testing.T) {
 	}
 }
 
+func TestLatestVersion_PreferIncompatibleOverPrerelease(t *testing.T) {
+	defer ResetTestDB(testDB, t)
+	ctx := context.Background()
+
+	for _, mod := range []struct {
+		version    string
+		modulePath string
+	}{
+		{
+			version:    "v0.0.0-20201007032633-0806396f153e",
+			modulePath: sample.ModulePath,
+		},
+		{
+			version:    "v2.0.0+incompatible",
+			modulePath: sample.ModulePath,
+		},
+	} {
+		m := sample.LegacyDefaultModule()
+		m.Version = mod.version
+		m.ModulePath = mod.modulePath
+
+		if err := testDB.InsertModule(ctx, m); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	for _, tc := range []struct {
+		modulePath string
+		want       string
+	}{
+		{
+			modulePath: sample.ModulePath,
+			want:       "v2.0.0+incompatible",
+		},
+	} {
+		isLatest, err := isLatestVersion(ctx, testDB.db, tc.modulePath, tc.want)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if !isLatest {
+			t.Errorf("%s is not the latest version", tc.want)
+		}
+	}
+}
+
 func TestDeleteModule(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), testTimeout)
 	defer cancel()