1 files changed, 83 insertions, 0 deletions
diff --git a/up_test.go b/up_test.go
new file mode 100644
index 0000000..de31c59
--- /dev/null
+++ b/up_test.go
@@ -0,0 +1,83 @@
+package main
+
+import "testing"
+
+func Test_Editor_insert(test *testing.T) {
+	cases := []struct {
+		comment   string
+		e         Editor
+		insert    []rune
+		wantValue []rune
+	}{
+		{
+			comment: "prepend ASCII char",
+			e: Editor{
+				value:  []rune(`abc`),
+				cursor: 0,
+			},
+			insert:    []rune{'X'},
+			wantValue: []rune(`Xabc`),
+		},
+		{
+			comment: "prepend UTF char",
+			e: Editor{
+				value:  []rune(`abc`),
+				cursor: 0,
+			},
+			insert:    []rune{'☃'},
+			wantValue: []rune(`☃abc`),
+		},
+		{
+			comment: "insert ASCII char",
+			e: Editor{
+				value:  []rune(`abc`),
+				cursor: 1,
+			},
+			insert:    []rune{'X'},
+			wantValue: []rune(`aXbc`),
+		},
+		{
+			comment: "insert UTF char",
+			e: Editor{
+				value:  []rune(`abc`),
+				cursor: 1,
+			},
+			insert:    []rune{'☃'},
+			wantValue: []rune(`a☃bc`),
+		},
+		{
+			comment: "append ASCII char",
+			e: Editor{
+				value:  []rune(`abc`),
+				cursor: 3,
+			},
+			insert:    []rune{'X'},
+			wantValue: []rune(`abcX`),
+		},
+		{
+			comment: "append UTF char",
+			e: Editor{
+				value:  []rune(`abc`),
+				cursor: 3,
+			},
+			insert:    []rune{'☃'},
+			wantValue: []rune(`abc☃`),
+		},
+		{
+			comment: "insert 2 ASCII chars",
+			e: Editor{
+				value:  []rune(`abc`),
+				cursor: 1,
+			},
+			insert:    []rune{'X', 'Y'},
+			wantValue: []rune(`aXYbc`),
+		},
+	}
+
+	for _, c := range cases {
+		c.e.insert(c.insert...)
+		if string(c.e.value) != string(c.wantValue) {
+			test.Errorf("%q: bad value\nwant: %q\nhave: %q", c.comment, c.wantValue, c.e.value)
+		}
+	}
+}