Split mixin command args by whitespace

Some mixin commands have whitespace and right now we are passing them in
as packed into a single array element when executing the command

exec.Cmd("aws", []string{"ec2", "run-instances", "--security-group-ids
group1 group2"})

When the debug command is printed, we can't tell that this has happened,
and why the command failed. What needs to happen is that when there is a
space, and it's not enclosed in double quotes, it should be split into
its own array element

exec.Cmd("aws", []string{"ec2", "run-instances", "--security-group-ids",
"group1", "group2"})

pkg/exec/builder/execute.go

@@ -2,6 +2,7 @@ package builder
 
 import (
 	"bytes"
+	"encoding/csv"
 	"fmt"
 	"io"
 	"strings"
@@ -77,6 +78,11 @@ func ExecuteStep(cxt *context.Context, step ExecutableStep) (string, error) {
 	}
 	args = append(args, flags.ToSlice(dashes)...)
 
+	// Split up any arguments or flags that have spaces so that we pass them as separate array elements
+	// It doesn't show up any differently in the printed command, but it matters to how the command
+	// it executed against the system.
+	args = expandOnWhitespace(args)
+
 	cmd := cxt.NewCommand(step.GetCommand(), args...)
 	output := &bytes.Buffer{}
 	cmd.Stdout = io.MultiWriter(cxt.Out, output)
@@ -99,3 +105,27 @@ func ExecuteStep(cxt *context.Context, step ExecutableStep) (string, error) {
 
 	return output.String(), nil
 }
+
+// expandOnWhitespace finds elements with multiple words that are not "glued" together with quotes
+// and splits them into separate elements in the slice
+func expandOnWhitespace(slice []string) []string {
+	expandedSlice := make([]string, 0, len(slice))
+	for _, chunk := range slice {
+		r := csv.NewReader(strings.NewReader(chunk))
+		r.Comma = ' '
+		r.LazyQuotes = true
+		group, err := r.Read()
+		if err != nil {
+			if err == io.EOF {
+				break
+			}
+			expandedSlice = append(expandedSlice, chunk)
+		} else {
+			for _, chunkette := range group {
+				expandedSlice = append(expandedSlice, chunkette)
+			}
+		}
+	}
+
+	return expandedSlice
+}

pkg/exec/builder/execute_test.go

@@ -59,3 +59,25 @@ func TestExecuteSingleStepAction(t *testing.T) {
 	exists, _ = c.FileSystem.Exists("/cnab/app/porter/outputs/jsonpath")
 	assert.True(t, exists, "jsonpath output was not evaluated")
 }
+
+func Test_expandOnWhitespace(t *testing.T) {
+	t.Run("split whitespace", func(t *testing.T) {
+		result := expandOnWhitespace([]string{"cmd", "--myarg", "val1 val2"})
+		assert.Equal(t, []string{"cmd", "--myarg", "val1", "val2"}, result)
+	})
+
+	t.Run("keep double quoted whitespace", func(t *testing.T) {
+		result := expandOnWhitespace([]string{"cmd", "--myarg", "\"val1 val2\" val3"})
+		assert.Equal(t, []string{"cmd", "--myarg", "val1 val2", "val3"}, result)
+	})
+
+	t.Run("embedded single quote", func(t *testing.T) {
+		result := expandOnWhitespace([]string{"cmd", "--myarg", `"Patty O'Brien" true`})
+		assert.Equal(t, []string{"cmd", "--myarg", "Patty O'Brien", "true"}, result)
+	})
+
+	t.Run("embedded double quote", func(t *testing.T) {
+		result := expandOnWhitespace([]string{"cmd", "--myarg", `"Patty O"Brien" true`})
+		assert.Equal(t, []string{"cmd", "--myarg", "Patty O\"Brien", "true"}, result)
+	})
+}