Make --expect additive

Similarly to --bind or --color.

--expect used to replace the previously specified keys, and
fzf#wrap({'options': '--expect=f1'}) wouldn't work as expected. It
forced us to come up with some ugly hacks like the following:

https://github.com/junegunn/fzf.vim/blob/13b27c45c8bdf6c3a41376bb83e4895edadf8c7e/autoload/fzf/vim.vim#L1086

2 files changed, 13 insertions, 2 deletions

diff --git a/src/options.go b/src/options.go
index afd46b9e..e2f33f81 100644
--- a/src/options.go
+++ b/src/options.go
@@ -962,7 +962,9 @@ func parseOptions(opts *Options, allArgs []string) {
 		case "--algo":
 			opts.FuzzyAlgo = parseAlgo(nextString(allArgs, &i, "algorithm required (v1|v2)"))
 		case "--expect":
-			opts.Expect = parseKeyChords(nextString(allArgs, &i, "key names required"), "key names required")
+			for k, v := range parseKeyChords(nextString(allArgs, &i, "key names required"), "key names required") {
+				opts.Expect[k] = v
+			}
 		case "--no-expect":
 			opts.Expect = make(map[int]string)
 		case "--tiebreak":
@@ -1140,7 +1142,9 @@ func parseOptions(opts *Options, allArgs []string) {
 			} else if match, value := optString(arg, "--toggle-sort="); match {
 				parseToggleSort(opts.Keymap, value)
 			} else if match, value := optString(arg, "--expect="); match {
-				opts.Expect = parseKeyChords(value, "key names required")
+				for k, v := range parseKeyChords(value, "key names required") {
+					opts.Expect[k] = v
+				}
 			} else if match, value := optString(arg, "--tiebreak="); match {
 				opts.Criteria = parseTiebreak(value)
 			} else if match, value := optString(arg, "--color="); match {
diff --git a/src/options_test.go b/src/options_test.go
index d3c93450..22f4e4ee 100644
--- a/src/options_test.go
+++ b/src/options_test.go
@@ -414,3 +414,10 @@ func TestPreviewOpts(t *testing.T) {
 		t.Error(opts.Preview)
 	}
 }
+
+func TestAdditiveExpect(t *testing.T) {
+	opts := optsFor("--expect=a", "--expect", "b", "--expect=c")
+	if len(opts.Expect) != 3 {
+		t.Error(opts.Expect)
+	}
+}