Move `IsReadmeFile*` from `modules/markup/` to `modules/util` (#22877)

These functions don't examine contents, just filenames, so they don't
fit in well in a markup module.

This was originally part of
https://github.com/go-gitea/gitea/pull/22177.

Signed-off-by: Nick Guenther <nick.guenther@polymtl.ca>

4 files changed, 120 insertions, 129 deletions

diff --git a/modules/markup/renderer.go b/modules/markup/renderer.go
index 5a31e961f..df2c9ebfc 100644
--- a/modules/markup/renderer.go
+++ b/modules/markup/renderer.go
@@ -317,41 +317,3 @@ func IsMarkupFile(name, markup string) bool {
 	}
 	return false
 }
-
-// IsReadmeFile reports whether name looks like a README file
-// based on its name.
-func IsReadmeFile(name string) bool {
-	name = strings.ToLower(name)
-	if len(name) < 6 {
-		return false
-	} else if len(name) == 6 {
-		return name == "readme"
-	}
-	return name[:7] == "readme."
-}
-
-// IsReadmeFileExtension reports whether name looks like a README file
-// based on its name. It will look through the provided extensions and check if the file matches
-// one of the extensions and provide the index in the extension list.
-// If the filename is `readme.` with an unmatched extension it will match with the index equaling
-// the length of the provided extension list.
-// Note that the '.' should be provided in ext, e.g ".md"
-func IsReadmeFileExtension(name string, ext ...string) (int, bool) {
-	name = strings.ToLower(name)
-	if len(name) < 6 || name[:6] != "readme" {
-		return 0, false
-	}
-
-	for i, extension := range ext {
-		extension = strings.ToLower(extension)
-		if name[6:] == extension {
-			return i, true
-		}
-	}
-
-	if name[6] == '.' {
-		return len(ext), true
-	}
-
-	return 0, false
-}
diff --git a/modules/markup/renderer_test.go b/modules/markup/renderer_test.go
index 624558c3f..0791081f9 100644
--- a/modules/markup/renderer_test.go
+++ b/modules/markup/renderer_test.go
@@ -2,94 +2,3 @@
 // SPDX-License-Identifier: MIT
 
 package markup_test
-
-import (
-	"testing"
-
-	. "code.gitea.io/gitea/modules/markup"
-
-	_ "code.gitea.io/gitea/modules/markup/markdown"
-
-	"github.com/stretchr/testify/assert"
-)
-
-func TestMisc_IsReadmeFile(t *testing.T) {
-	trueTestCases := []string{
-		"readme",
-		"README",
-		"readME.mdown",
-		"README.md",
-		"readme.i18n.md",
-	}
-	falseTestCases := []string{
-		"test.md",
-		"wow.MARKDOWN",
-		"LOL.mDoWn",
-		"test",
-		"abcdefg",
-		"abcdefghijklmnopqrstuvwxyz",
-		"test.md.test",
-		"readmf",
-	}
-
-	for _, testCase := range trueTestCases {
-		assert.True(t, IsReadmeFile(testCase))
-	}
-	for _, testCase := range falseTestCases {
-		assert.False(t, IsReadmeFile(testCase))
-	}
-
-	type extensionTestcase struct {
-		name     string
-		expected bool
-		idx      int
-	}
-
-	exts := []string{".md", ".txt", ""}
-	testCasesExtensions := []extensionTestcase{
-		{
-			name:     "readme",
-			expected: true,
-			idx:      2,
-		},
-		{
-			name:     "readme.md",
-			expected: true,
-			idx:      0,
-		},
-		{
-			name:     "README.md",
-			expected: true,
-			idx:      0,
-		},
-		{
-			name:     "ReAdMe.Md",
-			expected: true,
-			idx:      0,
-		},
-		{
-			name:     "readme.txt",
-			expected: true,
-			idx:      1,
-		},
-		{
-			name:     "readme.doc",
-			expected: true,
-			idx:      3,
-		},
-		{
-			name: "readmee.md",
-		},
-		{
-			name:     "readme..",
-			expected: true,
-			idx:      3,
-		},
-	}
-
-	for _, testCase := range testCasesExtensions {
-		idx, ok := IsReadmeFileExtension(testCase.name, exts...)
-		assert.Equal(t, testCase.expected, ok)
-		assert.Equal(t, testCase.idx, idx)
-	}
-}
diff --git a/modules/util/path.go b/modules/util/path.go
index e060b527f..74acb7a85 100644
--- a/modules/util/path.go
+++ b/modules/util/path.go
@@ -11,6 +11,7 @@ import (
 	"path/filepath"
 	"regexp"
 	"runtime"
+	"strings"
 )
 
 // EnsureAbsolutePath ensure that a path is absolute, making it
@@ -201,3 +202,41 @@ func CommonSkip(name string) bool {
 
 	return false
 }
+
+// IsReadmeFileName reports whether name looks like a README file
+// based on its name.
+func IsReadmeFileName(name string) bool {
+	name = strings.ToLower(name)
+	if len(name) < 6 {
+		return false
+	} else if len(name) == 6 {
+		return name == "readme"
+	}
+	return name[:7] == "readme."
+}
+
+// IsReadmeFileExtension reports whether name looks like a README file
+// based on its name. It will look through the provided extensions and check if the file matches
+// one of the extensions and provide the index in the extension list.
+// If the filename is `readme.` with an unmatched extension it will match with the index equaling
+// the length of the provided extension list.
+// Note that the '.' should be provided in ext, e.g ".md"
+func IsReadmeFileExtension(name string, ext ...string) (int, bool) {
+	name = strings.ToLower(name)
+	if len(name) < 6 || name[:6] != "readme" {
+		return 0, false
+	}
+
+	for i, extension := range ext {
+		extension = strings.ToLower(extension)
+		if name[6:] == extension {
+			return i, true
+		}
+	}
+
+	if name[6] == '.' {
+		return len(ext), true
+	}
+
+	return 0, false
+}
diff --git a/modules/util/path_test.go b/modules/util/path_test.go
index 5794df1eb..93f4f67cf 100644
--- a/modules/util/path_test.go
+++ b/modules/util/path_test.go
@@ -55,3 +55,84 @@ func TestFileURLToPath(t *testing.T) {
 		}
 	}
 }
+
+func TestMisc_IsReadmeFileName(t *testing.T) {
+	trueTestCases := []string{
+		"readme",
+		"README",
+		"readME.mdown",
+		"README.md",
+		"readme.i18n.md",
+	}
+	falseTestCases := []string{
+		"test.md",
+		"wow.MARKDOWN",
+		"LOL.mDoWn",
+		"test",
+		"abcdefg",
+		"abcdefghijklmnopqrstuvwxyz",
+		"test.md.test",
+		"readmf",
+	}
+
+	for _, testCase := range trueTestCases {
+		assert.True(t, IsReadmeFileName(testCase))
+	}
+	for _, testCase := range falseTestCases {
+		assert.False(t, IsReadmeFileName(testCase))
+	}
+
+	type extensionTestcase struct {
+		name     string
+		expected bool
+		idx      int
+	}
+
+	exts := []string{".md", ".txt", ""}
+	testCasesExtensions := []extensionTestcase{
+		{
+			name:     "readme",
+			expected: true,
+			idx:      2,
+		},
+		{
+			name:     "readme.md",
+			expected: true,
+			idx:      0,
+		},
+		{
+			name:     "README.md",
+			expected: true,
+			idx:      0,
+		},
+		{
+			name:     "ReAdMe.Md",
+			expected: true,
+			idx:      0,
+		},
+		{
+			name:     "readme.txt",
+			expected: true,
+			idx:      1,
+		},
+		{
+			name:     "readme.doc",
+			expected: true,
+			idx:      3,
+		},
+		{
+			name: "readmee.md",
+		},
+		{
+			name:     "readme..",
+			expected: true,
+			idx:      3,
+		},
+	}
+
+	for _, testCase := range testCasesExtensions {
+		idx, ok := IsReadmeFileExtension(testCase.name, exts...)
+		assert.Equal(t, testCase.expected, ok)
+		assert.Equal(t, testCase.idx, idx)
+	}
+}