Add test coverage for config cleaning

Adds unit tests

modules/common/util/template_util.go

@@ -64,34 +64,24 @@ type Template struct {
 func removeSubsequentNewLines(rawConf string) string {
 	lines := strings.Split(rawConf, "\n")
 	var result []string
-	var prevLineWasBlank bool
 
 	for _, line := range lines {
 		trimmedLine := strings.TrimSpace(line)
 
-		if trimmedLine == "" {
-			prevLineWasBlank = true
-			// if current line is blank, no need to add it in result
-		} else {
+		if trimmedLine != "" {
 			if strings.HasPrefix(trimmedLine, "[") && strings.HasSuffix(trimmedLine, "]") {
 				// section-header
-				if len(result) > 0 && !prevLineWasBlank {
-					result = append(result, "")
-				}
-				var sectionHeaderLine string
 				if len(result) > 0 {
-					// new section-hearder
-					sectionHeaderLine = "\n" + line
+					// new section-header
+					result = append(result, "\n"+line)
 				} else {
-					sectionHeaderLine = line
+					// top section-header
+					result = append(result, line)
 				}
-				result = append(result, sectionHeaderLine)
 			} else {
 				// secion-body
 				result = append(result, line)
 			}
-			// reset flag
-			prevLineWasBlank = false
 		}
 	}
 

modules/common/util/template_util_test.go

@@ -266,3 +266,179 @@ func TestGetTemplateData(t *testing.T) {
 		})
 	}
 }
+
+func TestRemoveSubsequentNewLines(t *testing.T) {
+	tests := []struct {
+		name    string
+		raw     string
+		cleaned string
+	}{
+		{
+			name:    "Empty input",
+			raw:     "",
+			cleaned: "",
+		},
+		{
+			name:    "Single empty line",
+			raw:     "\n",
+			cleaned: "",
+		},
+		{
+			name:    "Two empty lines",
+			raw:     "\n\n",
+			cleaned: "",
+		},
+		{
+			name:    "Insert newline at end of file",
+			raw:     "foo",
+			cleaned: "foo\n",
+		},
+		{
+			name:    "Remove starting empty line",
+			raw:     "\nfoo",
+			cleaned: "foo\n",
+		},
+		{
+			name:    "Remove starting empty lines",
+			raw:     "\n\nfoo",
+			cleaned: "foo\n",
+		},
+		{
+			name:    "Remove extra empty line at the end",
+			raw:     "foo\n\n",
+			cleaned: "foo\n",
+		},
+		{
+			name:    "Remove extra empty lines at the end",
+			raw:     "foo\n\n\n",
+			cleaned: "foo\n",
+		},
+		{
+			name:    "Keep subsequent data lines",
+			raw:     "foo\nbar",
+			cleaned: "foo\nbar\n",
+		},
+		{
+			name:    "Remove empty line between subsequent data",
+			raw:     "foo\n\nbar",
+			cleaned: "foo\nbar\n",
+		},
+		{
+			name:    "Extra spaces around data lines are kept",
+			raw:     "\n\n  foo  \n\n  bar  ",
+			cleaned: "  foo  \n  bar  \n",
+		},
+		{
+			name:    "Remove extra lines with spaces only",
+			raw:     " \n  \nfoo\n \nbar\n  \n  ",
+			cleaned: "foo\nbar\n",
+		},
+		{
+			name:    "Remove starting empty line from section header",
+			raw:     "\n[foo]",
+			cleaned: "[foo]\n",
+		},
+		{
+			name:    "Remove starting empty lines from section header",
+			raw:     "\n\n[foo]",
+			cleaned: "[foo]\n",
+		},
+		{
+			name:    "Remove extra empty line after section header",
+			raw:     "[foo]\n\n",
+			cleaned: "[foo]\n",
+		},
+		{
+			name:    "Remove extra empty lines after section header",
+			raw:     "[foo]\n\n\n",
+			cleaned: "[foo]\n",
+		},
+		{
+			name:    "Insert empty line after section header at the end",
+			raw:     "[foo]",
+			cleaned: "[foo]\n",
+		},
+		{
+			name:    "Keep one empty line between section headers",
+			raw:     "[foo]\n\n[bar]",
+			cleaned: "[foo]\n\n[bar]\n",
+		},
+
+		// This ws failing as it inserts two empty lines between sections. But that is inconsistent
+		// as if there are two empty lines between sections then one is removed.
+		// See next test case.
+		{
+			name:    "Insert one empty line between section headers",
+			raw:     "[foo]\n[bar]",
+			cleaned: "[foo]\n\n[bar]\n",
+		},
+		{
+			name:    "Remove more empty lines between section headers",
+			raw:     "[foo]\n\n\n[bar]",
+			cleaned: "[foo]\n\n[bar]\n",
+		},
+		{
+			name:    "Spaces are kept around section lines but not in the empty line in between",
+			raw:     "\n [foo]  \n  \n  [bar] ",
+			cleaned: " [foo]  \n\n  [bar] \n",
+		},
+		{
+			name:    "Remove extra empty line between section header and data",
+			raw:     "[foo]\n\nbar",
+			cleaned: "[foo]\nbar\n",
+		},
+		{
+			name:    "Remove extra empty lines between section header and data",
+			raw:     "[foo]\n\n\nbar",
+			cleaned: "[foo]\nbar\n",
+		},
+
+		// This was failing as it insert two extra lines. It is inconsistent as if there are
+		// two empty lines between sections then one is removed. See next test case.
+		{
+			name:    "Insert extra line between sections",
+			raw:     "[foo]\nbar\n[goo]\nbaz",
+			cleaned: "[foo]\nbar\n\n[goo]\nbaz\n",
+		},
+		{
+			name:    "Remove extra lines between sections",
+			raw:     "[foo]\nbar\n\n\n[goo]\nbaz",
+			cleaned: "[foo]\nbar\n\n[goo]\nbaz\n",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			g := NewWithT(t)
+
+			cleaned := removeSubsequentNewLines(tt.raw)
+			g.Expect(cleaned).To(Equal(tt.cleaned))
+		})
+	}
+}
+
+// Run the cleaning twice on an input and ensure that the second cleaning
+// does nothing as the first run cleaned everything
+// This was failing due to empty line handling between sections is unstable.
+func TestRemoveSubsequentNewLinesIsStable(t *testing.T) {
+	g := NewWithT(t)
+
+	input := `
+
+[foo]
+boo=1
+
+
+bar=1
+[goo]
+
+
+baz=1
+
+
+`
+	cleaned := removeSubsequentNewLines(input)
+	cleaned2 := removeSubsequentNewLines(cleaned)
+
+	g.Expect(cleaned2).To(Equal(cleaned))
+}