diff --git a/extension/definition_list_test.go b/extension/definition_list_test.go
index 6280a64..d9dfa6c 100644
--- a/extension/definition_list_test.go
+++ b/extension/definition_list_test.go
@@ -17,5 +17,5 @@ func TestDefinitionList(t *testing.T) {
 			DefinitionList,
 		),
 	)
-	testutil.DoTestCaseFile(markdown, "_test/definition_list.txt", t)
+	testutil.DoTestCaseFile(markdown, "_test/definition_list.txt", t, testutil.ParseCliCaseArg()...)
 }
diff --git a/extension/footnote_test.go b/extension/footnote_test.go
index 447d177..08e29d8 100644
--- a/extension/footnote_test.go
+++ b/extension/footnote_test.go
@@ -17,5 +17,5 @@ func TestFootnote(t *testing.T) {
 			Footnote,
 		),
 	)
-	testutil.DoTestCaseFile(markdown, "_test/footnote.txt", t)
+	testutil.DoTestCaseFile(markdown, "_test/footnote.txt", t, testutil.ParseCliCaseArg()...)
 }
diff --git a/extension/linkify_test.go b/extension/linkify_test.go
index 18d1331..d096aca 100644
--- a/extension/linkify_test.go
+++ b/extension/linkify_test.go
@@ -18,7 +18,7 @@ func TestLinkify(t *testing.T) {
 			Linkify,
 		),
 	)
-	testutil.DoTestCaseFile(markdown, "_test/linkify.txt", t)
+	testutil.DoTestCaseFile(markdown, "_test/linkify.txt", t, testutil.ParseCliCaseArg()...)
 }
 
 func TestLinkifyWithAllowedProtocols(t *testing.T) {
diff --git a/extension/strikethrough_test.go b/extension/strikethrough_test.go
index 2569bff..3274c0e 100644
--- a/extension/strikethrough_test.go
+++ b/extension/strikethrough_test.go
@@ -17,5 +17,5 @@ func TestStrikethrough(t *testing.T) {
 			Strikethrough,
 		),
 	)
-	testutil.DoTestCaseFile(markdown, "_test/strikethrough.txt", t)
+	testutil.DoTestCaseFile(markdown, "_test/strikethrough.txt", t, testutil.ParseCliCaseArg()...)
 }
diff --git a/extension/table_test.go b/extension/table_test.go
index baacdf7..cea3c8e 100644
--- a/extension/table_test.go
+++ b/extension/table_test.go
@@ -17,5 +17,5 @@ func TestTable(t *testing.T) {
 			Table,
 		),
 	)
-	testutil.DoTestCaseFile(markdown, "_test/table.txt", t)
+	testutil.DoTestCaseFile(markdown, "_test/table.txt", t, testutil.ParseCliCaseArg()...)
 }
diff --git a/extension/tasklist_test.go b/extension/tasklist_test.go
index 6a04cba..e376227 100644
--- a/extension/tasklist_test.go
+++ b/extension/tasklist_test.go
@@ -17,5 +17,5 @@ func TestTaskList(t *testing.T) {
 			TaskList,
 		),
 	)
-	testutil.DoTestCaseFile(markdown, "_test/tasklist.txt", t)
+	testutil.DoTestCaseFile(markdown, "_test/tasklist.txt", t, testutil.ParseCliCaseArg()...)
 }
diff --git a/extension/typographer_test.go b/extension/typographer_test.go
index 0b1b66f..f8eded1 100644
--- a/extension/typographer_test.go
+++ b/extension/typographer_test.go
@@ -17,5 +17,5 @@ func TestTypographer(t *testing.T) {
 			Typographer,
 		),
 	)
-	testutil.DoTestCaseFile(markdown, "_test/typographer.txt", t)
+	testutil.DoTestCaseFile(markdown, "_test/typographer.txt", t, testutil.ParseCliCaseArg()...)
 }
diff --git a/extra_test.go b/extra_test.go
index bddfe3f..892848e 100644
--- a/extra_test.go
+++ b/extra_test.go
@@ -16,7 +16,7 @@ func TestExtras(t *testing.T) {
 		html.WithXHTML(),
 		html.WithUnsafe(),
 	))
-	testutil.DoTestCaseFile(markdown, "_test/extra.txt", t)
+	testutil.DoTestCaseFile(markdown, "_test/extra.txt", t, testutil.ParseCliCaseArg()...)
 }
 
 func TestEndsWithNonSpaceCharacters(t *testing.T) {
diff --git a/options_test.go b/options_test.go
index 4375b63..9607eb3 100644
--- a/options_test.go
+++ b/options_test.go
@@ -15,5 +15,5 @@ func TestAttributeAndAutoHeadingID(t *testing.T) {
 			parser.WithAutoHeadingID(),
 		),
 	)
-	testutil.DoTestCaseFile(markdown, "_test/options.txt", t)
+	testutil.DoTestCaseFile(markdown, "_test/options.txt", t, testutil.ParseCliCaseArg()...)
 }
diff --git a/testutil/testutil.go b/testutil/testutil.go
index ac2f2a2..e24f89d 100644
--- a/testutil/testutil.go
+++ b/testutil/testutil.go
@@ -32,8 +32,25 @@ type MarkdownTestCase struct {
 const attributeSeparator = "//- - - - - - - - -//"
 const caseSeparator = "//= = = = = = = = = = = = = = = = = = = = = = = =//"
 
+// ParseCliCaseArg parses -case command line args.
+func ParseCliCaseArg() []int {
+	ret := []int{}
+	for _, a := range os.Args {
+		if strings.HasPrefix(a, "case=") {
+			parts := strings.Split(a, "=")
+			for _, cas := range strings.Split(parts[1], ",") {
+				value, err := strconv.Atoi(strings.TrimSpace(cas))
+				if err == nil {
+					ret = append(ret, value)
+				}
+			}
+		}
+	}
+	return ret
+}
+
 // DoTestCaseFile runs test cases in a given file.
-func DoTestCaseFile(m goldmark.Markdown, filename string, t TestingT) {
+func DoTestCaseFile(m goldmark.Markdown, filename string, t TestingT, no ...int) {
 	fp, err := os.Open(filename)
 	if err != nil {
 		panic(err)
@@ -93,7 +110,18 @@ func DoTestCaseFile(m goldmark.Markdown, filename string, t TestingT) {
 			buf = append(buf, text)
 		}
 		c.Expected = strings.Join(buf, "\n")
-		cases = append(cases, c)
+		shouldAdd := len(no) == 0
+		if !shouldAdd {
+			for _, n := range no {
+				if n == c.No {
+					shouldAdd = true
+					break
+				}
+			}
+		}
+		if shouldAdd {
+			cases = append(cases, c)
+		}
 	}
 	DoTestCases(m, cases, t)
 }