Fixes #852 optionally add last newline

Tested with Linux and Windows, by appending many new functions to
a single stack.yml file.

Signed-off-by: Kyle Brennan <kylos101@gmail.com>

Author: kylos101

commands/new_function.go

@@ -152,6 +152,11 @@ Download templates:
 		}
 
 		fileName = appendFile
+
+		if err := addEofNewlines("./" + fileName); err != nil {
+			return err
+		}
+
 		outputMsg = fmt.Sprintf("Stack file updated: %s\n", fileName)
 
 	} else {
@@ -346,3 +351,28 @@ Cannot have duplicate function names in same yaml file`, functionName, appendFil
 
 	return nil
 }
+
+func addEofNewlines(fileName string) error {
+	bytes, err := os.ReadFile(fileName)
+	if err != nil {
+		return fmt.Errorf("could not open '%s' to check for new lines %s", fileName, err)
+	}
+
+	content := string(bytes)
+	hasLastNewline := strings.HasSuffix(content, "\n")
+	if hasLastNewline {
+		return nil
+	}
+
+	file, err := os.OpenFile(fileName, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0600)
+	if err != nil {
+		return fmt.Errorf("could not open '%s' to append new lines %s", fileName, err)
+	}
+	defer file.Close()
+
+	if _, err = file.WriteString("\n\n"); err != nil {
+		return fmt.Errorf("could not write to '%s' to append new lines %s", fileName, err)
+	}
+
+	return nil
+}

commands/new_function_test.go

@@ -372,6 +372,11 @@ func tearDownNewFunction(t *testing.T, functionName string) {
 			t.Log(err)
 		}
 	}
+	if _, err := os.Stat("stack.yml"); err == nil {
+		if err := os.Remove("stack.yml"); err != nil {
+			t.Log(err)
+		}
+	}
 	hDir := handlerDir
 	if len(hDir) == 0 {
 		hDir = functionName
@@ -423,3 +428,58 @@ func Test_getPrefixValue_Flag(t *testing.T) {
 		t.Errorf("want %s, got %s", want, val)
 	}
 }
+
+func Test_addEofNewlines_works(t *testing.T) {
+	table := []struct {
+		funcName string
+	}{
+		// TODO: after #906 is fixed
+		// -f or --yaml will work
+		// and we can change stack to func1
+		{"stack"},
+		{"func2"},
+		{"func3"},
+	}
+	resetForTest()
+	templatePullLocalTemplateRepo(t)
+
+	defer tearDownFetchTemplates(t)
+	const stackFile = "stack.yml"
+
+	for i, row := range table {
+		const functionLang = "ruby"
+
+		parameters := []string{
+			"new",
+			row.funcName,
+			"--lang=" + functionLang,
+		}
+
+		if i == 0 {
+			// there's a bug where this doesn't get honored
+			// as a workaround, func1 is "stack" in the test table
+			// this way we predictability create stack.yml
+			parameters = append(parameters, "--yaml="+stackFile)
+		} else {
+			parameters = append(parameters, "--append="+stackFile)
+		}
+
+		faasCmd.SetArgs(nil)
+		faasCmd.SetArgs(parameters)
+		faasCmd.Execute()
+
+		// drop last two bytes (\n\n) for the first function
+		if i == 0 {
+			func(fileName string) {
+				file, _ := os.OpenFile(fileName, os.O_RDWR, 0600)
+				defer file.Close()
+				fileStats, _ := file.Stat()
+				file.Truncate(fileStats.Size() - 2)
+			}(stackFile)
+		}
+	}
+
+	for _, row := range table {
+		defer tearDownNewFunction(t, row.funcName)
+	}
+}