feat: blueprint-test file logger

infra/blueprint-test/pkg/utils/logger.go

@@ -17,9 +17,13 @@
 package utils
 
 import (
+	"fmt"
+	"io"
+	"os"
 	"testing"
 
 	"github.com/gruntwork-io/terratest/modules/logger"
+	terraTesting "github.com/gruntwork-io/terratest/modules/testing"
 )
 
 // GetLoggerFromT returns a logger based on test verbosity
@@ -29,3 +33,33 @@ func GetLoggerFromT() *logger.Logger {
 	}
 	return logger.Discard
 }
+
+// TestFileLogger is a logger that writes to disk instead of stdout.
+// This is useful when you want to redirect verbose logs of long running tests to disk.
+type TestFileLogger struct {
+	pth string
+	w   io.WriteCloser
+}
+
+// NewTestFileLogger returns a TestFileLogger logger that can be used with the WithLogger option.
+func NewTestFileLogger(t *testing.T, pth string) (*logger.Logger, func(t *testing.T)) {
+	f, err := os.OpenFile(pth, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		t.Fatalf("error opening file %s: %v", pth, err)
+	}
+	fl := TestFileLogger{
+		pth: pth,
+		w:   f,
+	}
+	return logger.New(fl), fl.Close
+}
+
+func (fl TestFileLogger) Logf(t terraTesting.TestingT, format string, args ...interface{}) {
+	logger.DoLog(t, 3, fl.w, fmt.Sprintf(format, args...))
+}
+
+func (fl TestFileLogger) Close(t *testing.T) {
+	if err := fl.w.Close(); err != nil {
+		t.Fatalf("error closing file logger %s: %v", fl.pth, err)
+	}
+}

infra/blueprint-test/pkg/utils/logger_test.go

@@ -0,0 +1,53 @@
+/**
+ * Copyright 2022 Google LLC
+ *
+ * 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 utils
+
+import (
+	"fmt"
+	"os"
+	"path"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNewTestFileLogger(t *testing.T) {
+	tests := []struct {
+		name    string
+		content string
+	}{
+		{
+			name:    "simple",
+			content: "foo",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert := assert.New(t)
+			testFile := path.Join(t.TempDir(), fmt.Sprintf("%s.log", tt.name))
+			fl, flClose := NewTestFileLogger(t, testFile)
+			fl.Logf(t, tt.content)
+			flClose(t)
+			gotContent, err := os.ReadFile(testFile)
+			assert.NoError(err)
+			assert.Contains(string(gotContent), "foo")
+			// assert we are wrapping logger.DoLog which prints stack/test info
+			assert.Contains(string(gotContent), fmt.Sprintf("TestNewTestFileLogger/%s", tt.name))
+			assert.Contains(string(gotContent), "logger_test.go")
+		})
+	}
+}