v doc: fix an infinite recursion in `v doc .` executed in /tmp. Add tests for v.doc.get_parent_mod/1 .

vlib/v/doc/doc_private_fn_test.v

@@ -0,0 +1,47 @@
+module doc
+
+import os
+
+fn testsuite_begin() {
+	os.chdir(@VMODROOT)
+	eprintln('>> @VMODROOT: ' + @VMODROOT)
+}
+
+fn test_get_parent_mod_on_root_folder() {
+	// TODO: add an equivalent windows check for c:\
+	$if !windows {
+		assert '---' == get_parent_mod('/') or {
+			assert err.msg == 'root folder reached'
+			'---'
+		}
+	}
+}
+
+fn test_get_parent_mod_current_folder() {
+	// TODO: this should may be return '' reliably on windows too:
+	// assert '' == get_parent_mod('.') or {
+	//	assert err.msg == 'No V files found.'
+	//	'---'
+	// }
+}
+
+fn test_get_parent_mod_on_temp_dir() ? {
+	// TODO: fix this on windows
+	$if !windows {
+		assert get_parent_mod(os.temp_dir()) ? == ''
+	}
+}
+
+fn test_get_parent_mod_normal_cases() ? {
+	assert '---' == get_parent_mod(os.join_path(@VMODROOT, 'vlib/v')) or {
+		assert err.msg == 'No V files found.'
+		'---'
+	}
+	// TODO: WTF?
+	// assert get_parent_mod(os.join_path(@VMODROOT, 'vlib', 'v', 'doc', 'doc.v')) ? == 'v.v.doc'
+	assert get_parent_mod(os.join_path(@VMODROOT, 'vlib', 'v', 'doc')) ? == 'v'
+	assert get_parent_mod(os.join_path(@VMODROOT, 'vlib', 'os', 'os.v')) ? == 'os'
+	assert get_parent_mod(os.join_path(@VMODROOT, 'cmd')) ? == ''
+	assert get_parent_mod(os.join_path(@VMODROOT, 'cmd', 'tools', 'modules', 'testing',
+		'common.v')) ? == 'testing'
+}

vlib/v/doc/module.v

@@ -11,16 +11,19 @@ import v.pref
 // For example, given something like /languages/v/vlib/x/websocket/tests/autobahn
 // it returns `x.websocket.tests`, because /languages/v/ has v.mod file in it.
 // NB: calling this is expensive, so keep the result, instead of recomputing it.
+// TODO: turn this to a Doc method, so that the new_vdoc_preferences call here can
+// be removed.
 fn get_parent_mod(input_dir string) ?string {
-	$if windows {
-		// windows root path is C: or D:
-		if input_dir.len <= 2 {
-			return error('root folder reached')
-		}
-	} $else {
-		if input_dir.len == 0 {
-			return error('root folder reached')
-		}
+	// windows root path is C: or D:
+	if input_dir.len == 2 && input_dir[1] == `:` {
+		return error('root folder reached')
+	}
+	// unix systems have / at the top:
+	if input_dir == '/' {
+		return error('root folder reached')
+	}
+	if input_dir == '' {
+		return error('no input folder')
 	}
 	base_dir := os.dir(input_dir)
 	input_dir_name := os.file_name(base_dir)