bufmodule: test NewModuleForBucket (#1486)

`NewModuleForBucket` didn't have any coverage, so here's some I added as
I was working on other things.

private/bufpkg/bufmodule/module_test.go

@@ -0,0 +1,124 @@
+// Copyright 2020-2022 Buf Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package bufmodule
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/bufbuild/buf/private/bufpkg/bufmodule/bufmoduleref"
+	"github.com/bufbuild/buf/private/pkg/storage/storagemem"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func testNewModuleForBucket(
+	t *testing.T,
+	desc string,
+	files map[string][]byte,
+	isError bool,
+	isNil bool,
+	pins []bufmoduleref.ModulePin,
+	documentation string,
+	license string,
+) {
+	t.Run(desc, func(t *testing.T) {
+		t.Parallel()
+		ctx := context.Background()
+		bucket, err := storagemem.NewReadBucket(files)
+		require.NoError(t, err)
+		module, err := newModuleForBucket(ctx, bucket)
+		if isError {
+			assert.Error(t, err, "isError")
+			return
+		}
+		require.NoError(t, err)
+		if isNil {
+			assert.Nil(t, module, "isNil")
+			return
+		}
+		require.NotNil(t, module, "!isNil")
+
+		assert.Equal(t, pins, module.dependencyModulePins, "pins")
+		assert.Equal(t, documentation, module.documentation, "documentation")
+		assert.Equal(t, license, module.license, "license")
+	})
+}
+
+func TestNewModuleForBucket(t *testing.T) {
+	testNewModuleForBucket(t,
+		"an empty bucket is a valid parse",
+		map[string][]byte{},
+		false,
+		false,
+		[]bufmoduleref.ModulePin{},
+		"",
+		"",
+	)
+
+	wantPin, err := bufmoduleref.NewModulePin(
+		"foo",
+		"bar",
+		"baz",
+		"",
+		"62f35d8aed1149c291d606d958a7ce32",
+		time.Time{},
+	)
+	require.NoError(t, err)
+	testNewModuleForBucket(t,
+		"pins are consumed",
+		map[string][]byte{
+			"buf.lock": []byte(`
+version: v1
+deps:
+  - remote: foo
+    owner: bar
+    repository: baz
+    commit: 62f35d8aed1149c291d606d958a7ce32
+`),
+		},
+		false,
+		false,
+		[]bufmoduleref.ModulePin{wantPin},
+		"",
+		"",
+	)
+
+	testNewModuleForBucket(t,
+		"license and documentation are consumed",
+		map[string][]byte{
+			"buf.md":  []byte("foo"),
+			"LICENSE": []byte("bar"),
+		},
+		false,
+		false,
+		[]bufmoduleref.ModulePin{},
+		"foo",
+		"bar",
+	)
+
+	testNewModuleForBucket(t,
+		"invalid buf.lock",
+		map[string][]byte{
+			"buf.lock": []byte("version: v0"),
+		},
+		true,
+		false,
+		[]bufmoduleref.ModulePin{},
+		"",
+		"",
+	)
+}