Add a helper tool to emit Makefile snippets

This loads the whole go universe one time, so should be faster that
repeated calls to `go list`

hack/make-rules/helpers/go2make/pkgwalk_test.go

@@ -0,0 +1,222 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+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 main
+
+import (
+	"path"
+	"reflect"
+	"sort"
+	"testing"
+)
+
+func Test_WalkPkg(t *testing.T) {
+	testCases := []struct {
+		pkg      string
+		fail     bool
+		expected []string
+	}{
+		{
+			pkg:  "./testdata/nonexistent-dir",
+			fail: true,
+		},
+		{
+			pkg:      "./testdata/dir-without-gofiles",
+			expected: []string{"./testdata/dir-without-gofiles"},
+		},
+		{
+			pkg:      "./testdata/dir-with-gofiles",
+			expected: []string{"./testdata/dir-with-gofiles", "./testdata/dir-with-gofiles/subdir"},
+		},
+	}
+
+	for i, tc := range testCases {
+		visited := []string{}
+		err := WalkPkg(tc.pkg, func(imp, abs string) error {
+			if _, base := path.Split(imp); base == "skipme" {
+				return ErrSkipPkg
+			}
+			visited = append(visited, imp)
+			return nil
+		})
+		if err != nil && tc.fail {
+			continue
+		}
+		if err != nil {
+			t.Errorf("[%d] unexpected error: %v", i, err)
+			continue
+		}
+		if tc.fail {
+			t.Errorf("[%d] expected error", i)
+			continue
+		}
+		if !reflect.DeepEqual(visited, tc.expected) {
+			t.Errorf("[%d] unexpected results: %v", i, visited)
+		}
+	}
+}
+func Test_findPackage(t *testing.T) {
+	testCases := []struct {
+		pkg  string
+		fail bool
+	}{
+		{
+			pkg:  "./testdata/nonexistent-dir",
+			fail: true,
+		},
+		{
+			pkg: "./testdata/dir-without-gofiles",
+		},
+		{
+			pkg: "./testdata/dir-with-gofiles",
+		},
+	}
+
+	for i, tc := range testCases {
+		_, err := findPackage(tc.pkg)
+		if err != nil && tc.fail {
+			continue
+		}
+		if err != nil {
+			t.Errorf("[%d] unexpected error: %v", i, err)
+			continue
+		}
+		if tc.fail {
+			t.Errorf("[%d] expected error", i)
+			continue
+		}
+	}
+}
+
+func Test_readDirInfos(t *testing.T) {
+	testCases := []struct {
+		dir      string
+		fail     bool
+		expected map[string]bool
+	}{
+		{
+			dir:  "./testdata/nonexistent-dir",
+			fail: true,
+		},
+		{
+			dir:      "./testdata/dir-without-gofiles",
+			expected: map[string]bool{"README": true},
+		},
+		{
+			dir: "./testdata/dir-with-gofiles",
+			expected: map[string]bool{
+				"README":      true,
+				"foo.go":      true,
+				"bar.go":      true,
+				"subdir":      true,
+				"testdata":    true,
+				"_underscore": true,
+				".dot":        true,
+				"skipme":      true,
+			},
+		},
+	}
+
+	for i, tc := range testCases {
+		infos, err := readDirInfos(tc.dir)
+		if err != nil && tc.fail {
+			continue
+		}
+		if err != nil {
+			t.Errorf("[%d] unexpected error: %v", i, err)
+			continue
+		}
+		if tc.fail {
+			t.Errorf("[%d] expected error", i)
+			continue
+		}
+		result := make([]string, len(infos))
+		sorted := make([]string, len(infos))
+		for i, inf := range infos {
+			result[i] = inf.Name()
+			sorted[i] = inf.Name()
+		}
+		sort.Strings(sorted)
+		if !reflect.DeepEqual(result, sorted) {
+			t.Errorf("[%d] result was not sorted: %v", i, result)
+		}
+		for _, r := range result {
+			if !tc.expected[r] {
+				t.Errorf("[%d] got unexpected result: %s", i, r)
+			} else {
+				delete(tc.expected, r)
+			}
+		}
+		for r := range tc.expected {
+			t.Errorf("[%d] missing expected result: %s", i, r)
+		}
+	}
+}
+
+func Test_readDirNames(t *testing.T) {
+	testCases := []struct {
+		dir      string
+		fail     bool
+		expected map[string]bool
+	}{
+		{
+			dir:  "./testdata/nonexistent-dir",
+			fail: true,
+		},
+		{
+			dir:      "./testdata/dir-without-gofiles",
+			expected: map[string]bool{"README": true},
+		},
+		{
+			dir: "./testdata/dir-with-gofiles",
+			expected: map[string]bool{
+				"README":      true,
+				"foo.go":      true,
+				"bar.go":      true,
+				"subdir":      true,
+				"testdata":    true,
+				"_underscore": true,
+				".dot":        true,
+				"skipme":      true,
+			},
+		},
+	}
+
+	for i, tc := range testCases {
+		result, err := readDirNames(tc.dir)
+		if err != nil && tc.fail {
+			continue
+		}
+		if err != nil {
+			t.Errorf("[%d] unexpected error: %v", i, err)
+			continue
+		}
+		if tc.fail {
+			t.Errorf("[%d] expected error", i)
+			continue
+		}
+		for _, r := range result {
+			if !tc.expected[r] {
+				t.Errorf("[%d] got unexpected result: %s", i, r)
+			} else {
+				delete(tc.expected, r)
+			}
+		}
+		for r := range tc.expected {
+			t.Errorf("[%d] missing expected result: %s", i, r)
+		}
+	}
+}