run functions

vm/vm_test.go

@@ -296,3 +296,93 @@ func TestIndexExpressions(t *testing.T) {
 
 	runVmTests(t, tests)
 }
+
+func TestCallingFunctionsWithoutArguments(t *testing.T) {
+	tests := []vmTestCase{
+		{
+			input: `
+        let fivePlusTen = fn() { 5 + 10; };
+        fivePlusTen();
+        `,
+			expected: 15,
+		},
+		{
+			input: `
+        let one = fn() { 1; };
+        let two = fn() { 2; };
+        one() + two()
+        `,
+			expected: 3,
+		},
+		{
+			input: `
+        let a = fn() { 1 };
+        let b = fn() { a() + 1 };
+        let c = fn() { b() + 1 };
+        c();
+        `,
+			expected: 3,
+		},
+	}
+
+	runVmTests(t, tests)
+}
+
+func TestFunctionsWithReturnStatements(t *testing.T) {
+	tests := []vmTestCase{
+		{
+			input: `
+        let earlyExit = fn() { return 99; 100; };
+        earlyExit();
+        `,
+			expected: 99,
+		},
+		{
+			input: `
+        let earlyExit = fn() { return 99; return 100; };
+        earlyExit();
+        `,
+			expected: 99,
+		},
+	}
+
+	runVmTests(t, tests)
+}
+
+func TestFunctionsWithoutReturnValue(t *testing.T) {
+	tests := []vmTestCase{
+		{
+			input: `
+        let noReturn = fn() { };
+        noReturn();
+        `,
+			expected: Null,
+		},
+		{
+			input: `
+        let noReturn = fn() { };
+        let noReturnTwo = fn() { noReturn(); };
+        noReturn();
+        noReturnTwo();
+        `,
+			expected: Null,
+		},
+	}
+
+	runVmTests(t, tests)
+}
+
+func TestFirstClassFunctions(t *testing.T) {
+	tests := []vmTestCase{
+		{
+			input: `
+        let returnsOne = fn() { 1; };
+        let returnsOneReturner = fn() { returnsOne; };
+        returnsOneReturner()();
+        `,
+			expected: 1,
+		},
+	}
+
+	runVmTests(t, tests)
+}