Make the function results separator configurable (#4778)

* Make the function results separator configurable

Signed-off-by: Kushal Harish Naidu 

* Address IsZero() and add table driven tests for TestPrintFnResult

Signed-off-by: Kushal Harish Naidu 

---------

Signed-off-by: Kushal Harish Naidu 

Author: kushnaidu

pkg/fn/runtime/runner.go

@@ -328,7 +328,7 @@ func (fr *FunctionRunner) Filter(input []*yaml.RNode) (output []*yaml.RNode, err
 	output, err = fr.do(input)
 	if err != nil {
 		pr.Printf("[FAIL] %q in %v\n", fnName, time.Since(t0).Truncate(time.Millisecond)) // TODO: use OptPrintf
-		printFnResult(fr.ctx, fr.fnResult)
+		printFnResult(fr.ctx, fr.fnResult, fr.opts.LogOptions.ResultSeparator)
 		if fnErr, ok := goerrors.AsType[*ExecError](err); ok {
 			printFnExecErr(fr.ctx, fnErr)
 			return nil, errors.ErrAlreadyHandled
@@ -337,7 +337,7 @@ func (fr *FunctionRunner) Filter(input []*yaml.RNode) (output []*yaml.RNode, err
 	}
 	if !fr.disableCLIOutput {
 		pr.Printf("[PASS] %q in %v\n", fnName, time.Since(t0).Truncate(time.Millisecond)) // TODO: use OptPrintf
-		printFnResult(fr.ctx, fr.fnResult)
+		printFnResult(fr.ctx, fr.fnResult, fr.opts.LogOptions.ResultSeparator)
 		printFnStderr(fr.ctx, fr.fnResult.Stderr)
 	}
 	return output, err
@@ -536,20 +536,24 @@ func populateResourceRef(item *yaml.RNode, resultItem *fnresultv1.ResultItem) er
 }
 
 // printFnResult prints given function result in a user-friendly format on kpt CLI.
-func printFnResult(ctx context.Context, fnResult *fnresultv1.Result) {
+// separator joins the per-item result lines (defaults to "\n"); embedding
+// applications can set it to e.g. "; " to keep the [Results] output single-line.
+func printFnResult(ctx context.Context, fnResult *fnresultv1.Result, separator string) {
 	pr := printer.FromContextOrDie(ctx)
 	if len(fnResult.Results) > 0 {
 		// function returned structured results
 		var lines []string
 		for _, item := range fnResult.Results {
 			lines = append(lines, item.String())
 		}
+		if separator == "" {
+			separator = "\n"
+		}
 		ri := &runneroptions.SingleLineFormatter{
-			Title:     "[Results]",
-			Lines:     lines,
-			UseQuote:  false,
-			Separator: "\n",
-
+			Title:      "[Results]",
+			Lines:      lines,
+			UseQuote:   false,
+			Separator:  separator,
 			Indent:     2,
 			LineIndent: 2,
 		}

pkg/fn/runtime/runner_test.go

@@ -1077,3 +1077,46 @@ data:
 		assert.Equal(t, "ns-b", meta.Namespace)
 	})
 }
+
+func TestPrintFnResult(t *testing.T) {
+	results := []fnresultv1.ResultItem{
+		{Severity: framework.Info, Message: "first"},
+		{Severity: framework.Error, Message: "second"},
+	}
+
+	tests := map[string]struct {
+		results   []fnresultv1.ResultItem
+		separator string
+		expected  string
+	}{
+		"no results produces no output": {
+			results:   nil,
+			separator: "",
+			expected:  "",
+		},
+		"empty separator preserves newline output": {
+			results:   results,
+			separator: "",
+			expected:  "  [Results]:\n    [info]: first\n    [error]: second\n",
+		},
+		"custom separator joins result items": {
+			results:   results,
+			separator: "; ",
+			expected:  "  [Results]:\n    [info]: first;     [error]: second\n",
+		},
+	}
+
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			out := &bytes.Buffer{}
+			errOut := &bytes.Buffer{}
+			ctx := printer.WithContext(context.Background(), printer.New(out, errOut))
+
+			printFnResult(ctx, &fnresultv1.Result{Results: tc.results}, tc.separator)
+
+			// printFnResult writes to the printer's stderr stream.
+			assert.Equal(t, tc.expected, errOut.String())
+			assert.Equal(t, "", out.String())
+		})
+	}
+}

pkg/lib/runneroptions/runneroptions.go

@@ -104,10 +104,16 @@ type LogOptions struct {
 	// TruncateImageName determines whether the full image name or just the base
 	// name and the tag will be logged.
 	TruncateImageName bool
+
+	// ResultSeparator is used to join the per-item lines of a function's
+	// structured [Results] output. Defaults to "\n" (multi-line) when empty.
+	// Embedding applications (e.g. Porch) can set this to "; " to keep the
+	// result output on a single line for log-friendliness.
+	ResultSeparator string
 }
 
 func (o *LogOptions) IsZero() bool {
-	return o.PkgNameFormat == "" && o.PkgNameSep == "" && o.PkgNameID == 0 && !o.TruncateImageName
+	return o.PkgNameFormat == "" && o.PkgNameSep == "" && o.PkgNameID == 0 && !o.TruncateImageName && o.ResultSeparator == ""
 }
 
 func (o *LogOptions) FillDefaults() {

pkg/lib/runneroptions/runneroptions_test.go

@@ -119,3 +119,35 @@ func TestDefaultImagePrefix(t *testing.T) {
 		}
 	})
 }
+
+func TestLogOptions_IsZero(t *testing.T) {
+	tests := map[string]struct {
+		opts LogOptions
+		want bool
+	}{
+		"fully empty is zero": {
+			opts: LogOptions{},
+			want: true,
+		},
+		"separator-only is not zero": {
+			opts: LogOptions{ResultSeparator: "; "},
+			want: false,
+		},
+		"pkg name format set is not zero": {
+			opts: LogOptions{PkgNameFormat: "%s"},
+			want: false,
+		},
+		"truncate image name set is not zero": {
+			opts: LogOptions{TruncateImageName: true},
+			want: false,
+		},
+	}
+
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			if got := tc.opts.IsZero(); got != tc.want {
+				t.Errorf("IsZero() = %v, want %v", got, tc.want)
+			}
+		})
+	}
+}