FIX: pricePerBroadcaster JSON file line breaks parsing bug (#2914)

* FIX: pricePerBroadcaster JSON file line breaks parsing bug

---------

Co-authored-by: Rick Staa <[email protected]>

CHANGELOG_PENDING.md

@@ -20,6 +20,8 @@
 
 ### Bug Fixes 🐞
 
+- \[#2914](https://github.com/livepeer/go-livepeer/issues/2912) fixes a bug that prevented `pricePerBroadcaster` JSON files with line-breaks from being parsed correctly (@rickstaa).
+
 #### CLI
 
 #### General

common/readfromfile.go

@@ -1,9 +1,9 @@
 package common
 
 import (
-	"bufio"
 	"fmt"
 	"os"
+	"strings"
 )
 
 // ReadFromFile attempts to read a file at the supplied location.
@@ -16,25 +16,18 @@ func ReadFromFile(s string) (string, error) {
 		return s, err
 	}
 	if info.IsDir() {
-		// If the supplied string is a directory,
-		// assume it is the pass and return it
-		// along with an approptiate error.
+		// If the supplied string is a directory, return it along with an appropriate error.
 		return s, fmt.Errorf("supplied path is a directory")
 	}
-	file, err := os.Open(s)
+	bytes, err := os.ReadFile(s)
 	if err != nil {
 		return s, err
 	}
-	scanner := bufio.NewScanner(file)
-	scanner.Split(bufio.ScanLines)
+	txt := strings.TrimSpace(string(bytes))
 
-	scanner.Scan()
-	txtline := scanner.Text()
-	file.Close()
-
-	if len(txtline) == 0 {
+	if len(txt) <= 0 {
 		return s, fmt.Errorf("supplied file is empty")
 	}
 
-	return txtline, nil
+	return txt, nil
 }

common/readfromfile_test.go

@@ -88,14 +88,29 @@ func TestReadFromFile_FileExistsOneLine(t *testing.T) {
 	assert.Equal(expectedOutput, output)
 }
 
+// Check that we can reliably read a single line value from the file, even when it ends in a newline / whitespace
+func TestReadFromFile_FileExistsEndsInNewline(t *testing.T) {
+	input :=
+		`something
+`
+	f, err := os.CreateTemp(os.TempDir(), "TestReadFromFile_FileExistsEndsInNewline*")
+	require.NoError(t, err)
+	defer os.Remove(f.Name())
+
+	_, err = f.WriteString(input)
+	require.NoError(t, err)
+
+	output, err := ReadFromFile(f.Name())
+	require.NoError(t, err)
+	require.Equal(t, "something", output)
+}
+
 func TestReadFromFile_FileExistsMultiline(t *testing.T) {
-	assert := assert.New(t)
 	require := require.New(t)
 
 	input :=
 		`something
 somethingelse`
-	expectedOutput := "something"
 
 	tmpFile := "TestReadFromFile_FileExistsMultiline.txt"
 
@@ -112,7 +127,7 @@ somethingelse`
 
 	output, err := ReadFromFile(tmpFile)
 
-	assert.Nil(err)
+	require.NoError(err)
 	// ReadFromFile should the first line of the text file
-	assert.Equal(expectedOutput, output)
+	require.Equal(input, output)
 }