Add test method for DetectLint

Signed-off-by: Talon Bowler <talon.bowler@docker.com>

frontend/dockerfile/linter/linter.go

@@ -24,16 +24,15 @@ func (rule *LinterRule[F]) SetSkip(skip bool) {
 	rule.Skip = skip
 }
 
-func (rule *LinterRule[F]) Run(warn LintWarnFunc, location []parser.Range, txt ...string) error {
+func (rule *LinterRule[F]) Run(warn LintWarnFunc, location []parser.Range, txt ...string) {
 	if rule.Skip {
-		return nil
+		return
 	}
 	if len(txt) == 0 {
 		txt = []string{rule.Description}
 	}
 	short := strings.Join(txt, " ")
 	warn(rule.Name, rule.Description, rule.URL, short, location)
-	return nil
 }
 
 func LintFormatShort(rulename, msg string, startLine int) string {

frontend/dockerfile/parser/directives_test.go

@@ -103,3 +103,68 @@ RUN ls
 	_, _, _, ok = DetectSyntax([]byte(dt))
 	require.False(t, ok)
 }
+
+func TestDetectLint(t *testing.T) {
+	t.Parallel()
+
+	dt := `#lint = skip=all // opts
+FROM busybox
+`
+	ref, cmdline, loc, ok := DetectLint([]byte(dt))
+	require.True(t, ok)
+	require.Equal(t, ref, "skip=all")
+	require.Equal(t, cmdline, "skip=all // opts")
+	require.Equal(t, 1, loc[0].Start.Line)
+	require.Equal(t, 1, loc[0].End.Line)
+
+	dt = `#!/bin/sh
+# lint = skip=all
+FROM busybox
+`
+	ref, _, loc, ok = DetectLint([]byte(dt))
+	require.True(t, ok)
+	require.Equal(t, ref, "skip=all")
+	require.Equal(t, 2, loc[0].Start.Line)
+	require.Equal(t, 2, loc[0].End.Line)
+
+	dt = `#!/bin/sh
+
+# lint = skip=all
+`
+	_, _, _, ok = DetectLint([]byte(dt))
+	require.False(t, ok)
+
+	dt = `FROM busybox
+RUN ls
+`
+	ref, cmdline, _, ok = DetectLint([]byte(dt))
+	require.False(t, ok)
+	require.Equal(t, ref, "")
+	require.Equal(t, cmdline, "")
+
+	dt = `//lint=skip=all
+//key=value`
+	ref, _, _, ok = DetectLint([]byte(dt))
+	require.True(t, ok)
+	require.Equal(t, ref, "skip=all")
+
+	dt = `#!/bin/sh
+//lint=skip=all`
+	ref, _, _, ok = DetectLint([]byte(dt))
+	require.True(t, ok)
+	require.Equal(t, ref, "skip=all")
+
+	dt = `{"lint": "skip=all"}`
+	ref, _, _, ok = DetectLint([]byte(dt))
+	require.True(t, ok)
+	require.Equal(t, ref, "skip=all")
+
+	dt = `{"lint": "foo"`
+	_, _, _, ok = DetectLint([]byte(dt))
+	require.False(t, ok)
+
+	dt = `{"lint": "foo"}
+# syntax=bar`
+	_, _, _, ok = DetectLint([]byte(dt))
+	require.False(t, ok)
+}