我正在使用import { ActionsObservable } from 'redux-observable';
import { TestScheduler } from 'rxjs/testing';
// your epics to be tested
import epics from './stock';
// actions that you epic will emit
import {
getAll,
getAllStart,
getAllSuccess,
} from '../actions/stock';
// mock the state param (if your epic use it)
import { initialState } from '../reducers/stock';
const state = {
value: {
stock: initialState,
},
};
// mock your dependencies param
const dependencies = {
api: {},
stock: {
getAll() { // in my real code, this is a promise, here is just a normal function, perfect to be use with the of operator
return [];
},
},
Error: class Error {},
};
describe('stock epic', () => {
it('should return all products', (done) => {
// this is just copy-paste
const testScheduler = new TestScheduler((actual, expected) => {
expect(actual).toStrictEqual(expected);
});
testScheduler.run(({ cold, hot, expectObservable, expectSubscriptions, flush }) => {
expectObservable(
epics.getAll$(
ActionsObservable.of(getAll()), // transform action to action$
state, // pass mocked state
dependencies // pass mocked dependencies
)
).toBe(
// my epic has a delay(1000) call
'a 999ms (b|)', {
a: getAllStart(),
b: getAllSuccess()
}
);
done();
});
});
});
模块来使用csv读取csv文件。我是Python的新手，以下行为使我感到困惑。
编辑：之后请参阅原始问题。
csv.DictReader csv = csv.DictReader(csvFile)
print(list(csv)) # prints what I would expect, a sequence of OrderedDict's
print(list(csv)) # prints an empty list...
是否以某种方式突变了list？
原始问题：
csv def removeFooColumn(csv):
for row in csv:
del csv['Foo']
csv = csv.DictReader(csvFile)
print(list(csv)) # prints what I would expect, a sequence of OrderedDict's
removeFooColum(csv)
print(list(csv)) # prints an empty list...
函数中的序列发生什么了？
答案 0 :(得分：1)
csv.DictReader是 generator 迭代器，只能使用一次。解决方法：
def removeFooColumn(csv):
for row in csv:
del row['Foo']
csv = list(csv.DictReader(csvFile))
print(csv) # prints what I would expect, a sequence of OrderedDict's
removeFooColumn(csv)
print(csv) # prints an empty list...