```ruby
require "spec_helper"

describe Stream::Feed do
  it "should validate feed_id" do
    feed = Stream::Feed.new(nil, "slug", "user_id", "")
  end

  it "should validate user_id" do
    feed = Stream::Feed.new(nil, "slug", "user_id-1", "")
  end

  it "should refuse user_id with semicolon" do
    expect { Stream::Feed.new(nil, "slug", "user:id", "") }.to raise_error Stream::StreamInputData
  end

  it "should refuse feed_slug with dashes" do
    expect { Stream::Feed.new(nil, "feed-slug", "user_id", "") }.to raise_error Stream::StreamInputData
  end

  it "should refuse feed_slug with underscores" do
    expect { Stream::Feed.new(nil, "feed_slug", "user_id", "") }.to raise_error Stream::StreamInputData
  end
end
```

Fix spec for underscore support for feed slugs
user
```ruby
require "spec_helper"

describe Stream::Feed do
  it "should validate feed_id" do
    feed = Stream::Feed.new(nil, "slug", "user_id", "")
  end

  it "should validate user_id" do
    feed = Stream::Feed.new(nil, "slug", "user_id-1", "")
  end

  it "should refuse user_id with semicolon" do
    expect { Stream::Feed.new(nil, "slug", "user:id", "") }.to raise_error Stream::StreamInputData
  end

  it "should refuse feed_slug with dashes" do
    expect { Stream::Feed.new(nil, "feed-slug", "user_id", "") }.to raise_error Stream::StreamInputData
  end

  it "should not refuse feed_slug with underscores" do
    expect { Stream::Feed.new(nil, "feed_slug", "user_id", "") }.to_not raise_error Stream::StreamInputData
  end
end
```
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