1 files changed, 100 insertions, 0 deletions
diff --git a/pkg/gui/lbl/focus_test.go b/pkg/gui/lbl/focus_test.go
new file mode 100644
index 000000000..f36191ce5
--- /dev/null
+++ b/pkg/gui/lbl/focus_test.go
@@ -0,0 +1,100 @@
+package lbl
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNewOrigin(t *testing.T) {
+	type scenario struct {
+		name            string
+		origin          int
+		bufferHeight    int
+		firstLineIdx    int
+		lastLineIdx     int
+		selectedLineIdx int
+		selectMode      selectMode
+		expected        int
+	}
+
+	scenarios := []scenario{
+		{
+			name:            "selection above scroll window",
+			origin:          50,
+			bufferHeight:    100,
+			firstLineIdx:    10,
+			lastLineIdx:     10,
+			selectedLineIdx: 10,
+			selectMode:      LINE,
+			expected:        10,
+		},
+		{
+			name:            "selection below scroll window",
+			origin:          0,
+			bufferHeight:    100,
+			firstLineIdx:    150,
+			lastLineIdx:     150,
+			selectedLineIdx: 150,
+			selectMode:      LINE,
+			expected:        50,
+		},
+		{
+			name:            "selection within scroll window",
+			origin:          0,
+			bufferHeight:    100,
+			firstLineIdx:    50,
+			lastLineIdx:     50,
+			selectedLineIdx: 50,
+			selectMode:      LINE,
+			expected:        0,
+		},
+		{
+			name:            "range ending below scroll window with selection at end of range",
+			origin:          0,
+			bufferHeight:    100,
+			firstLineIdx:    40,
+			lastLineIdx:     150,
+			selectedLineIdx: 150,
+			selectMode:      RANGE,
+			expected:        50,
+		},
+		{
+			name:            "range ending below scroll window with selection at beginning of range",
+			origin:          0,
+			bufferHeight:    100,
+			firstLineIdx:    40,
+			lastLineIdx:     150,
+			selectedLineIdx: 40,
+			selectMode:      RANGE,
+			expected:        40,
+		},
+		{
+			name:            "range starting above scroll window with selection at beginning of range",
+			origin:          50,
+			bufferHeight:    100,
+			firstLineIdx:    40,
+			lastLineIdx:     150,
+			selectedLineIdx: 40,
+			selectMode:      RANGE,
+			expected:        40,
+		},
+		{
+			name:            "hunk extending beyond both bounds of scroll window",
+			origin:          50,
+			bufferHeight:    100,
+			firstLineIdx:    40,
+			lastLineIdx:     200,
+			selectedLineIdx: 70,
+			selectMode:      HUNK,
+			expected:        40,
+		},
+	}
+
+	for _, s := range scenarios {
+		s := s
+		t.Run(s.name, func(t *testing.T) {
+			assert.EqualValues(t, s.expected, calculateOrigin(s.origin, s.bufferHeight, s.firstLineIdx, s.lastLineIdx, s.selectedLineIdx, s.selectMode))
+		})
+	}
+}