spatial/r2: add tests for Vec.{Add,Sub,Scale}

spatial/r2/vector_test.go

@@ -0,0 +1,79 @@
+// Copyright ©2020 The Gonum Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package r2
+
+import "testing"
+
+func TestAdd(t *testing.T) {
+	for _, test := range []struct {
+		v1, v2 Vec
+		want   Vec
+	}{
+		{Vec{0, 0}, Vec{0, 0}, Vec{0, 0}},
+		{Vec{1, 0}, Vec{0, 0}, Vec{1, 0}},
+		{Vec{1, 2}, Vec{3, 4}, Vec{4, 6}},
+		{Vec{1, -3}, Vec{1, -6}, Vec{2, -9}},
+		{Vec{1, 2}, Vec{-1, -2}, Vec{}},
+	} {
+		t.Run("", func(t *testing.T) {
+			got := test.v1.Add(test.v2)
+
+			if got != test.want {
+				t.Fatalf(
+					"error: %v + %v: got=%v, want=%v",
+					test.v1, test.v2, got, test.want,
+				)
+			}
+		})
+	}
+}
+
+func TestSub(t *testing.T) {
+	for _, test := range []struct {
+		v1, v2 Vec
+		want   Vec
+	}{
+		{Vec{0, 0}, Vec{0, 0}, Vec{0, 0}},
+		{Vec{1, 0}, Vec{0, 0}, Vec{1, 0}},
+		{Vec{1, 2}, Vec{3, 4}, Vec{-2, -2}},
+		{Vec{1, -3}, Vec{1, -6}, Vec{0, 3}},
+		{Vec{1, 2}, Vec{1, 2}, Vec{}},
+	} {
+		t.Run("", func(t *testing.T) {
+			got := test.v1.Sub(test.v2)
+			if got != test.want {
+				t.Fatalf(
+					"error: %v - %v: got=%v, want=%v",
+					test.v1, test.v2, got, test.want,
+				)
+			}
+		})
+	}
+}
+
+func TestScale(t *testing.T) {
+	for _, test := range []struct {
+		a    float64
+		v    Vec
+		want Vec
+	}{
+		{3, Vec{0, 0}, Vec{0, 0}},
+		{1, Vec{1, 0}, Vec{1, 0}},
+		{0, Vec{1, 0}, Vec{0, 0}},
+		{3, Vec{1, 0}, Vec{3, 0}},
+		{-1, Vec{1, -3}, Vec{-1, 3}},
+		{2, Vec{1, -3}, Vec{2, -6}},
+		{10, Vec{1, 2}, Vec{10, 20}},
+	} {
+		t.Run("", func(t *testing.T) {
+			got := test.v.Scale(test.a)
+			if got != test.want {
+				t.Fatalf(
+					"error: %v * %v: got=%v, want=%v",
+					test.a, test.v, got, test.want)
+			}
+		})
+	}
+}