builtin-os-file: add function fileReadIterator() that creates an iterator over lines of a text file

t_builtin-os-file_test.go

@@ -5,6 +5,7 @@
 package expr
 
 import (
+	"io"
 	"testing"
 )
 
@@ -26,10 +27,13 @@ func TestFuncOs(t *testing.T) {
 		/*  13 */ {`builtin "os.file"; handle=fileClose(123)`, nil, `fileClose(): invalid file handle`},
 		/*  14 */ {`builtin "os.file"; handle=fileOpen("/tmp/dummy"); c=fileReadTextAll(handle); fileClose(handle); c`, "bye-bye", nil},
 		/*  15 */ {`builtin "os.file"; c=fileReadTextAll(123)`, nil, `fileReadTextAll(): invalid file handle 123 [int64]`},
+		/*  16 */ {`builtin "os.file"; it=fileReadIterator("test-file.txt"); it++`, "uno", nil},
+		/*  17 */ {`builtin "os.file"; it=fileReadIterator("test-file.txt"); it++;it++;it++`, nil, io.EOF.Error()},
+		/*  18 */ {`builtin "os.file"; it=fileReadIterator("test-file.txt"); it.clean`, nil, nil},
 	}
 
 	// t.Setenv("EXPR_PATH", ".")
 
-	//runTestSuiteSpec(t, section, inputs, 2)
-	runTestSuite(t, section, inputs)
+	runTestSuiteSpec(t, section, inputs, 18)
+	// runTestSuite(t, section, inputs)
 }