Preserve code blocks in templates.Normalizer (#118029)

* Preserve code blocks in templates.Normalizer

Currently, if templates.LongDesc function is invoked multiple times
for a string including a code block, this code block is converted to
invalid code block.

The reason of this issue is that blackfriday package, which templates package uses, relies on
4 * indentation to detect code blocks. This PR always preserves
4 * indentation in code blocks to always detect it code blocks in also
post invocations.

* Add indentations to test for code blocks

* Use strings.repeat for repetition

staging/src/k8s.io/kubectl/pkg/util/templates/markdown.go

@@ -58,7 +58,9 @@ func (r *ASCIIRenderer) RenderNode(w io.Writer, node *blackfriday.Node, entering
 		lines := []string{}
 		for _, line := range strings.Split(string(node.Literal), linebreak) {
 			trimmed := strings.Trim(line, " \t")
-			indented := r.Indentation + trimmed
+			// Adding 4 times of indentation will let blackfriday to accept
+			// this literal as Code or CodeBlock again in next invocation
+			indented := strings.Repeat(r.Indentation, 4) + trimmed
 			lines = append(lines, indented)
 		}
 		w.Write([]byte(strings.Join(lines, linebreak)))

staging/src/k8s.io/kubectl/pkg/util/templates/normalizers_test.go

@@ -64,7 +64,12 @@ func TestLongDescMarkdown(t *testing.T) {
 		{
 			desc: "Multi lines without order",
 			in:   "\t\t\t\t\tDescriptions.\n\n * Item.\n * Item2.",
-			out:  "Descriptions.\n  \n  *  Item.\n  *  Item2.",
+			out:  "Descriptions.\n        \n  *  Item.\n  *  Item2.",
+		},
+		{
+			desc: "With code block",
+			in:   "Line1\n\n\t<type>.<fieldName>[.<fieldName>]\n\nLine2",
+			out:  "Line1\n\n        <type>.<fieldName>[.<fieldName>]\n        \n Line2",
 		},
 	}
 
@@ -77,3 +82,51 @@ func TestLongDescMarkdown(t *testing.T) {
 		})
 	}
 }
+
+func TestMultiLongDescInvocation(t *testing.T) {
+	tests := []struct {
+		desc string
+		in   string
+		out  string
+	}{
+		{
+			desc: "Empty input produces empty output",
+			in:   "",
+			out:  "",
+		},
+		{
+			desc: "Single line text is preserved as is",
+			in:   "Some text",
+			out:  "Some text",
+		},
+		{
+			desc: "Consecutive new lines are combined into a single paragraph",
+			in:   "Line1\nLine2",
+			out:  "Line1 Line2",
+		},
+		{
+			desc: "Two paragraphs",
+			in:   "Line1\n\nLine2",
+			out:  "Line1\n\n Line2",
+		},
+		{
+			desc: "Leading and trailing spaces are stripped (single line)",
+			in:   "\t  \nThe text line  \n  \t",
+			out:  "The text line",
+		},
+		{
+			desc: "With code block",
+			in:   "Line1\n\n\t<type>.<fieldName>[.<fieldName>]\n\nLine2",
+			out:  "Line1\n\n        <type>.<fieldName>[.<fieldName>]\n        \n Line2",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.desc, func(t *testing.T) {
+			got := LongDesc(LongDesc(test.in))
+			if got != test.out {
+				t.Errorf("expected(%d):\n%s\n=====\ngot(%d):\n%s\n", len(test.out), test.out, len(got), got)
+			}
+		})
+	}
+}