chore: refactor header tests to iterate over a struct

car_test.go

@@ -237,6 +237,58 @@ func TestEOFHandling(t *testing.T) {
 }
 
 func TestBadHeaders(t *testing.T) {
+	testCases := []struct {
+		name   string
+		hex    string
+		errStr string // either the whole error string
+		errPfx string // or just the prefix
+	}{
+		{
+			"{version:2}",
+			"0aa16776657273696f6e02",
+			"invalid car version: 2",
+			"",
+		},
+		{
+			// an unfortunate error because we don't use a pointer
+			"{roots:[baeaaaa3bmjrq]}",
+			"13a165726f6f747381d82a480001000003616263",
+			"invalid car version: 0",
+			"",
+		}, {
+			"{version:\"1\",roots:[baeaaaa3bmjrq]}",
+			"1da265726f6f747381d82a4800010000036162636776657273696f6e6131",
+			"", "invalid header: ",
+		}, {
+			"{version:1}",
+			"0aa16776657273696f6e01",
+			"empty car, no roots",
+			"",
+		}, {
+			"{version:1,roots:{cid:baeaaaa3bmjrq}}",
+			"20a265726f6f7473a163636964d82a4800010000036162636776657273696f6e01",
+			"",
+			"invalid header: ",
+		}, {
+			"{version:1,roots:[baeaaaa3bmjrq],blip:true}",
+			"22a364626c6970f565726f6f747381d82a4800010000036162636776657273696f6e01",
+			"",
+			"invalid header: ",
+		}, {
+			"[1,[]]",
+			"03820180",
+			"",
+			"invalid header: ",
+		}, {
+			// this is an unfortunate error, it'd be nice to catch it better but it's
+			// very unlikely we'd ever see this in practice
+			"null",
+			"01f6",
+			"",
+			"invalid car version: 0",
+		},
+	}
+
 	makeCar := func(t *testing.T, byts string) error {
 		fixture, err := hex.DecodeString(byts)
 		if err != nil {
@@ -253,62 +305,18 @@ func TestBadHeaders(t *testing.T) {
 		}
 	})
 
-	t.Run("{version:2}", func(t *testing.T) {
-		err := makeCar(t, "0aa16776657273696f6e02")
-		if err.Error() != "invalid car version: 2" {
-			t.Fatalf("bad error: %v", err)
-		}
-	})
-
-	// an unfortunate error because we don't use a pointer
-	t.Run("{roots:[baeaaaa3bmjrq]}", func(t *testing.T) {
-		err := makeCar(t, "13a165726f6f747381d82a480001000003616263")
-		if err.Error() != "invalid car version: 0" {
-			t.Fatalf("bad error: %v", err)
-		}
-	})
-
-	t.Run("{version:\"1\",roots:[baeaaaa3bmjrq]}", func(t *testing.T) {
-		err := makeCar(t, "1da265726f6f747381d82a4800010000036162636776657273696f6e6131")
-		if !strings.HasPrefix(err.Error(), "invalid header: ") {
-			t.Fatalf("bad error: %v", err)
-		}
-	})
-
-	t.Run("{version:1}", func(t *testing.T) {
-		err := makeCar(t, "0aa16776657273696f6e01")
-		if err.Error() != "empty car, no roots" {
-			t.Fatalf("bad error: %v", err)
-		}
-	})
-
-	t.Run("{version:1,roots:{cid:baeaaaa3bmjrq}}", func(t *testing.T) {
-		err := makeCar(t, "20a265726f6f7473a163636964d82a4800010000036162636776657273696f6e01")
-		if !strings.HasPrefix(err.Error(), "invalid header: ") {
-			t.Fatalf("bad error: %v", err)
-		}
-	})
-
-	t.Run("{version:1,roots:[baeaaaa3bmjrq],blip:true}", func(t *testing.T) {
-		err := makeCar(t, "22a364626c6970f565726f6f747381d82a4800010000036162636776657273696f6e01")
-		if !strings.HasPrefix(err.Error(), "invalid header: ") {
-			t.Fatalf("bad error: %v", err)
-		}
-	})
-
-	t.Run("[1,[]]", func(t *testing.T) {
-		err := makeCar(t, "03820180")
-		if !strings.HasPrefix(err.Error(), "invalid header: ") {
-			t.Fatalf("bad error: %v", err)
-		}
-	})
-
-	// this is an unfortunate error, it'd be nice to catch it better but it's
-	// very unlikely we'd ever see this in practice
-	t.Run("null", func(t *testing.T) {
-		err := makeCar(t, "01f6")
-		if !strings.HasPrefix(err.Error(), "invalid car version: 0") {
-			t.Fatalf("bad error: %v", err)
-		}
-	})
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			err := makeCar(t, tc.hex)
+			if tc.errStr != "" {
+				if err.Error() != tc.errStr {
+					t.Fatalf("bad error: %v", err)
+				}
+			} else {
+				if !strings.HasPrefix(err.Error(), tc.errPfx) {
+					t.Fatalf("bad error: %v", err)
+				}
+			}
+		})
+	}
 }