✨ [logs] Add a file logger which only logs to a file (#477)

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Copyright (C) 2020-2022 Arm Limited or its affiliates and Contributors.
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SPDX-License-Identifier: Apache-2.0
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### Description

- extend the current file logger not to log to stderr or stdout



### Test Coverage

<!--
Please put an `x` in the correct box e.g. `[x]` to indicate the testing
coverage of this change.
-->

- [ ]  This change is covered by existing or additional automated tests.
- [ ] Manual testing has been performed (and evidence provided) as
automated testing was not feasible.
- [x] Additional tests are not required for this change (e.g.
documentation update).

changes/20240613181738.feature

@@ -0,0 +1 @@
+:sparkles: `[logs]` Add a way to use a `Loggers` as a plain `logr.Logger`

changes/20240614163145.feature

@@ -0,0 +1 @@
+:sparkles: `[logs]` Add a file logger which only logs to a file

utils/logs/file_logger.go

@@ -5,12 +5,22 @@
 
 package logs
 
-import "github.com/sirupsen/logrus"
+import (
+	"io"
 
-// NewFileLogger creates a logger to a file
+	"github.com/sirupsen/logrus"
+)
+
+// NewFileLogger creates a logger to a file.
 func NewFileLogger(logFile string, loggerSource string) (loggers Loggers, err error) {
 	return NewLogrusLoggerWithFileHook(logrus.New(), loggerSource, logFile)
+}
 
+// NewFileOnlyLogger creates a logger to a file such as NewFileLogger but logs are only sent to a file and will not be printed to StdErr or StdOut.
+func NewFileOnlyLogger(logFile string, loggerSource string) (loggers Loggers, err error) {
+	underlying := logrus.New()
+	underlying.SetOutput(io.Discard)
+	return NewLogrusLoggerWithFileHook(underlying, loggerSource, logFile)
 }
 
 // CreateFileLogger creates a logger to a file

utils/logs/file_logger_test.go

@@ -5,6 +5,7 @@
 package logs
 
 import (
+	"fmt"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -14,27 +15,44 @@ import (
 )
 
 func TestFileLogger(t *testing.T) {
-	file, err := filesystem.TempFileInTempDir("test-filelog-*.log")
-	require.NoError(t, err)
+	var tests = []struct {
+		loggerCreationFunc func(path string) (Loggers, error)
+	}{
+		{
+			loggerCreationFunc: func(path string) (Loggers, error) { return NewFileLogger(path, "Test") },
+		},
+		{
+			loggerCreationFunc: func(path string) (Loggers, error) { return NewFileOnlyLogger(path, "Test") },
+		},
+	}
+	for i := range tests {
+		test := tests[i]
+		t.Run(fmt.Sprintf("logger %v", i), func(t *testing.T) {
+			file, err := filesystem.TouchTempFileInTempDir("test-filelog-*.log")
+			require.NoError(t, err)
+
+			defer func() { _ = filesystem.Rm(file) }()
+
+			empty, err := filesystem.IsEmpty(file)
+			require.NoError(t, err)
+			assert.True(t, empty)
+
+			loggers, err := test.loggerCreationFunc(file)
+			require.NoError(t, err)
+
+			testLog(t, loggers)
+
+			empty, err = filesystem.IsEmpty(file)
+			require.NoError(t, err)
+			assert.False(t, empty)
+
+			content, err := filesystem.ReadFile(file)
+			require.NoError(t, err)
+			fmt.Println(string(content))
+
+			err = filesystem.Rm(file)
+			require.NoError(t, err)
+		})
+	}
 
-	err = file.Close()
-	require.NoError(t, err)
-
-	defer func() { _ = filesystem.Rm(file.Name()) }()
-
-	empty, err := filesystem.IsEmpty(file.Name())
-	require.NoError(t, err)
-	assert.True(t, empty)
-
-	loggers, err := NewFileLogger(file.Name(), "Test")
-	require.NoError(t, err)
-
-	testLog(t, loggers)
-
-	empty, err = filesystem.IsEmpty(file.Name())
-	require.NoError(t, err)
-	assert.False(t, empty)
-
-	err = filesystem.Rm(file.Name())
-	require.NoError(t, err)
 }