good good study, day day up!

vendor/gopl.io/ch7/eval/eval_test.go

@@ -0,0 +1,113 @@
+// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+
+package eval
+
+import (
+	"fmt"
+	"math"
+	"testing"
+)
+
+//!+Eval
+func TestEval(t *testing.T) {
+	tests := []struct {
+		expr string
+		env  Env
+		want string
+	}{
+		{"sqrt(A / pi)", Env{"A": 87616, "pi": math.Pi}, "167"},
+		{"pow(x, 3) + pow(y, 3)", Env{"x": 12, "y": 1}, "1729"},
+		{"pow(x, 3) + pow(y, 3)", Env{"x": 9, "y": 10}, "1729"},
+		{"5 / 9 * (F - 32)", Env{"F": -40}, "-40"},
+		{"5 / 9 * (F - 32)", Env{"F": 32}, "0"},
+		{"5 / 9 * (F - 32)", Env{"F": 212}, "100"},
+		//!-Eval
+		// additional tests that don't appear in the book
+		{"-1 + -x", Env{"x": 1}, "-2"},
+		{"-1 - x", Env{"x": 1}, "-2"},
+		//!+Eval
+	}
+	var prevExpr string
+	for _, test := range tests {
+		// Print expr only when it changes.
+		if test.expr != prevExpr {
+			fmt.Printf("\n%s\n", test.expr)
+			prevExpr = test.expr
+		}
+		expr, err := Parse(test.expr)
+		if err != nil {
+			t.Error(err) // parse error
+			continue
+		}
+		got := fmt.Sprintf("%.6g", expr.Eval(test.env))
+		fmt.Printf("\t%v => %s\n", test.env, got)
+		if got != test.want {
+			t.Errorf("%s.Eval() in %v = %q, want %q\n",
+				test.expr, test.env, got, test.want)
+		}
+	}
+}
+
+//!-Eval
+
+/*
+//!+output
+sqrt(A / pi)
+	map[A:87616 pi:3.141592653589793] => 167
+
+pow(x, 3) + pow(y, 3)
+	map[x:12 y:1] => 1729
+	map[x:9 y:10] => 1729
+
+5 / 9 * (F - 32)
+	map[F:-40] => -40
+	map[F:32] => 0
+	map[F:212] => 100
+//!-output
+
+// Additional outputs that don't appear in the book.
+
+-1 - x
+	map[x:1] => -2
+
+-1 + -x
+	map[x:1] => -2
+*/
+
+func TestErrors(t *testing.T) {
+	for _, test := range []struct{ expr, wantErr string }{
+		{"x % 2", "unexpected '%'"},
+		{"math.Pi", "unexpected '.'"},
+		{"!true", "unexpected '!'"},
+		{`"hello"`, "unexpected '\"'"},
+		{"log(10)", `unknown function "log"`},
+		{"sqrt(1, 2)", "call to sqrt has 2 args, want 1"},
+	} {
+		expr, err := Parse(test.expr)
+		if err == nil {
+			vars := make(map[Var]bool)
+			err = expr.Check(vars)
+			if err == nil {
+				t.Errorf("unexpected success: %s", test.expr)
+				continue
+			}
+		}
+		fmt.Printf("%-20s%v\n", test.expr, err) // (for book)
+		if err.Error() != test.wantErr {
+			t.Errorf("got error %s, want %s", err, test.wantErr)
+		}
+	}
+}
+
+/*
+//!+errors
+x % 2               unexpected '%'
+math.Pi             unexpected '.'
+!true               unexpected '!'
+"hello"             unexpected '"'
+
+log(10)             unknown function "log"
+sqrt(1, 2)          call to sqrt has 2 args, want 1
+//!-errors
+*/