1 files changed, 59 insertions, 0 deletions
diff --git a/flag_test.go b/flag_test.go
index ccbfadb..584a2c9 100644
--- a/flag_test.go
+++ b/flag_test.go
@@ -52,3 +52,62 @@ func TestFlagTSliceVar(s *testing.T) {
 	t.AssertErrorIs(nil, fs.Parse([]string{"-test=1", "-test=2", "-test=42,84"}))
 	t.AssertEqual([]int{1, 2, 42, 84}, fl)
 }
+
+func TestInitFlagSet(s *testing.T) {
+	t := core.T{T: s}
+
+	for _, tc := range []struct {
+		name string
+		env  []string
+		cfg  map[string]string
+		args []string
+
+		expInt      int
+		expIntSlice []int
+		expStr      string
+		expErr      error
+	}{
+		{
+			name: "ArgsOnly",
+			args: []string{"-int=42", "-int-slice=42,84"},
+
+			expInt:      42,
+			expIntSlice: []int{42, 84},
+		},
+		{
+			name: "EnvOnly",
+			env:  []string{"INT=42", "INT_SLICE=42,84"},
+
+			expInt:      42,
+			expIntSlice: []int{42, 84},
+		},
+		{
+			name: "CfgOnly",
+			cfg:  map[string]string{"int": "42", "int-slice": "42,84"},
+
+			expInt:      42,
+			expIntSlice: []int{42, 84},
+		},
+		{
+			name: "InOrder",
+			env:  []string{"STRING=Hello World!"},
+			cfg:  map[string]string{"string": "Hello Universe!", "int-slice": "42,84"},
+			args: []string{"-int=42", "-int-slice=21,42"},
+
+			expInt:      42,
+			expIntSlice: []int{21, 42},
+			expStr:      "Hello Universe!",
+		},
+	} {
+		t.Run(tc.name, func(t *core.T) {
+			fs := flag.NewFlagSet("", flag.PanicOnError)
+			fi := fs.Int("int", 0, "")
+			fl := core.FlagTSlice(fs, "int-slice", nil, "", strconv.Atoi, ",")
+			fm := fs.String("string", "", "")
+			t.AssertErrorIs(tc.expErr, core.InitFlagSet(fs, tc.env, tc.cfg, tc.args))
+			t.AssertEqual(tc.expInt, *fi)
+			t.AssertEqual(tc.expIntSlice, *fl)
+			t.AssertEqual(tc.expStr, *fm)
+		})
+	}
+}