golang: add test coverage, and fix handling of files with multiple build-tags

golang.go

@@ -20,20 +20,18 @@ func (g *golangApplier) CheckHeader(target *os.File, t *TagContext) (bool, error
 	}
 	target.Seek(0, 0)
 
+	if cFlags == AutoGenerated {
+		return true, nil
+	}
+
 	tbuf, err := os.ReadFile(filepath.Join(t.templatePath, "go.txt"))
 	if err != nil {
 		return false, err
 	}
 
-	if cFlags == AutoGenerated {
-		return true, nil
-	}
-
 	var templateBuf string
 	if cFlags == CompilerFlags {
-		for _, cbuf := range cbufs {
-			templateBuf += string(cbuf) + "\n"
-		}
+		templateBuf = strings.Join(cbufs, "\n") + "\n"
 		templateBuf += "\n"
 		templateBuf += string(tbuf)
 	} else {
@@ -95,10 +93,10 @@ func (g *golangApplier) ApplyHeader(path string, t *TagContext) error {
 	reader := bufio.NewReader(file)
 	if sFlags == CompilerFlags {
 		for _, f := range flags {
-			tFile.Write(f)
-			tFile.Write([]byte("\n"))
+			tFile.WriteString(f + "\n")
 			_, _, err = reader.ReadLine()
 		}
+		tFile.WriteString("\n")
 		_, _, err = reader.ReadLine()
 	}
 
@@ -124,37 +122,40 @@ func (g *golangApplier) ApplyHeader(path string, t *TagContext) error {
 	return nil
 }
 
-func (g *golangApplier) checkSpecialConditions(target *os.File) (uint8, [][]byte, error) {
+func (g *golangApplier) checkSpecialConditions(target *os.File) (uint8, []string, error) {
 	reader := bufio.NewReader(target)
 	buf, _, err := reader.ReadLine()
 	if err != nil {
 		return NormalFiles, nil, err
 	}
+	line := string(buf)
 
-	// Go 1.17 compiler flags (e.g., `//go:build !windows`)
-	if strings.HasPrefix(string(buf), "//go:") {
-		// read next line too: (`// +build !windows`)
-		if buf2, _, err := reader.ReadLine(); err == nil && strings.HasPrefix(string(buf2), "// +build ") {
-			return CompilerFlags, [][]byte{buf, buf2}, nil
-		}
-		return CompilerFlags, [][]byte{buf}, nil
+	if strings.HasPrefix(line, "//") && strings.Contains(line, "DO NOT EDIT") {
+		return AutoGenerated, nil, nil
 	}
 
-	// Old compiler flags (e.g., `// +build !windows`)
+	var buildTags []string
+
+	// Go 1.17 compiler flags (e.g., `//go:build !windows`), or old compiler
+	// flags (e.g., `// +build !windows`).
 	// checks for Package comments as per https://blog.golang.org/godoc-documenting-go-code
-	if strings.HasPrefix(string(buf), "//") &&
-		(strings.Contains(string(buf), "build") ||
-			strings.Contains(string(buf), "unix") ||
-			strings.Contains(string(buf), "linux") ||
-			strings.Contains(string(buf), "windows") ||
-			strings.Contains(string(buf), "darwin") ||
-			strings.Contains(string(buf), "freebsd")) &&
-		!strings.Contains(string(buf), "Package") {
-		return CompilerFlags, [][]byte{buf}, nil
-	}
-	if strings.HasPrefix(string(buf), "//") &&
-		(strings.Contains(string(buf), "DO NOT EDIT")) {
-		return AutoGenerated, nil, nil
+	if strings.HasPrefix(line, "//go:") || strings.HasPrefix(line, "// +build") {
+		buildTags = append(buildTags, line)
+
+		// read next line too: (`// +build !windows`)
+		for {
+			buf2, _, err := reader.ReadLine()
+			if err != nil {
+				break
+			}
+			if strings.HasPrefix(string(buf2), "// +build ") {
+				buildTags = append(buildTags, string(buf2))
+			} else {
+				break
+			}
+		}
+		return CompilerFlags, buildTags, nil
 	}
+
 	return NormalFiles, nil, nil
 }

golang_test.go

@@ -0,0 +1,118 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestGolangApplier_ApplyHeader(t *testing.T) {
+	tc := newGolangTagContext(t)
+	defer func() { _ = tc.templateFiles.dTemplateFile.Close() }()
+
+	tmpDir := t.TempDir()
+
+	files := []string{
+		"go.basic",
+		"go.generated",
+		"go.single-buildtag",
+		"go.multiple-buildtags",
+		"go.multiple-buildtags-legacy",
+	}
+
+	g := golangApplier{}
+	for _, f := range files {
+		fileName := f
+		t.Run(fileName, func(t *testing.T) {
+			testfile := filepath.Join(tmpDir, fileName)
+			copyFile(t, "./testdata/"+fileName, testfile)
+
+			err := g.ApplyHeader(testfile, &tc)
+			if err != nil {
+				t.Fatalf("failed to apply header to %s: %+v", testfile, err)
+			}
+			compareFiles(t, testfile, "./testdata/"+fileName+".golden")
+		})
+	}
+}
+
+func TestGolangApplier_CheckHeader(t *testing.T) {
+	tests := []struct {
+		fileName string
+		expected bool
+	}{
+		{
+			fileName: "go.basic",
+			expected: false,
+		},
+		{
+			fileName: "go.generated",
+			expected: true, // Generated files are not checked, and always "ok"
+		},
+		{
+			fileName: "go.single-buildtag",
+			expected: false,
+		},
+		{
+			fileName: "go.multiple-buildtags",
+			expected: false,
+		},
+		{
+			fileName: "go.multiple-buildtags-legacy",
+			expected: false,
+		},
+		{
+			fileName: "go.basic.golden",
+			expected: true, // Generated files are not checked, and always "ok"
+		},
+		{
+			fileName: "go.generated.golden",
+			expected: true, // Generated files are not checked, and always "ok"
+		},
+		{
+			fileName: "go.single-buildtag.golden",
+			expected: true,
+		},
+		{
+			fileName: "go.multiple-buildtags.golden",
+			expected: true,
+		},
+		{
+			fileName: "go.multiple-buildtags-legacy.golden",
+			expected: true,
+		},
+	}
+	g := golangApplier{}
+	tagContext := newGolangTagContext(t)
+	defer func() { _ = tagContext.templateFiles.dTemplateFile.Close() }()
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.fileName, func(t *testing.T) {
+			f, err := os.Open("./testdata/" + tc.fileName)
+			if err != nil {
+				t.Fatalf("failed to open file %s: %+v", tc.fileName, err)
+			}
+			defer func() { _ = f.Close() }()
+			found, err := g.CheckHeader(f, &tagContext)
+
+			if err != nil {
+				t.Fatalf("failed to check header: %+v", err)
+			}
+			if found != tc.expected {
+				t.Fail()
+			}
+		})
+	}
+}
+
+func newGolangTagContext(t *testing.T) TagContext {
+	t.Helper()
+	templateFile, err := loadTemplate("./testdata/templates/", "go.txt")
+	if err != nil {
+		t.Fatalf("failed to load Go template")
+	}
+	return TagContext{
+		templateFiles: TemplateFiles{goTemplateFile: templateFile},
+		templatePath:  "./testdata/templates/",
+	}
+}

testdata/go.basic

@@ -0,0 +1 @@
+package plugin

testdata/go.basic.golden

@@ -0,0 +1,17 @@
+/*
+   Copyright <YYYY> <Organization Name>
+
+   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 plugin

testdata/go.generated

@@ -0,0 +1,7 @@
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// versions:
+// 	protoc-gen-go v1.28.1
+// 	protoc        v3.20.1
+// source: github.com/containerd/containerd/api/types/metrics.proto
+
+package types

testdata/go.generated.golden

@@ -0,0 +1,7 @@
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// versions:
+// 	protoc-gen-go v1.28.1
+// 	protoc        v3.20.1
+// source: github.com/containerd/containerd/api/types/metrics.proto
+
+package types

testdata/go.multiple-buildtags

@@ -0,0 +1,7 @@
+//go:build (amd64 || arm64) && !static_build && !gccgo
+// +build amd64 arm64
+// +build !static_build
+// +build !gccgo
+
+// Package plugin does something.
+package plugin

testdata/go.multiple-buildtags-legacy

@@ -0,0 +1,6 @@
+// +build amd64 arm64
+// +build !static_build
+// +build !gccgo
+
+// Package plugin does something.
+package plugin

testdata/go.multiple-buildtags-legacy.golden

@@ -0,0 +1,22 @@
+// +build amd64 arm64
+// +build !static_build
+// +build !gccgo
+
+/*
+   Copyright <YYYY> <Organization Name>
+
+   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 plugin does something.
+package plugin

testdata/go.multiple-buildtags.golden

@@ -0,0 +1,23 @@
+//go:build (amd64 || arm64) && !static_build && !gccgo
+// +build amd64 arm64
+// +build !static_build
+// +build !gccgo
+
+/*
+   Copyright <YYYY> <Organization Name>
+
+   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 plugin does something.
+package plugin

testdata/go.single-buildtag

@@ -0,0 +1,4 @@
+//go:build amd64
+// +build amd64
+
+package main

testdata/go.single-buildtag.golden

@@ -0,0 +1,20 @@
+//go:build amd64
+// +build amd64
+
+/*
+   Copyright <YYYY> <Organization Name>
+
+   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

testdata/templates/go.txt

@@ -0,0 +1,16 @@
+/*
+   Copyright <YYYY> <Organization Name>
+
+   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.
+*/
+