How do I change the range of the x-axis with datetimes in matplotlib?

Edit:

Having seen actual data from the OP, all of the values are at the same date/time. So matplotlib is automatically zooming the x-axis out. You can still manually set the x-axis limits with datetime objects

---

If I do something like this on matplotlib v1.3.1:

import datetime
import matplotlib.pyplot as plt

x = [datetime.date(2014, 1, 29)] * 3 
y = [2, 4, 1]

fig, ax = plt.subplots()
ax.plot_date(x, y, markerfacecolor='CornflowerBlue', markeredgecolor='white')
fig.autofmt_xdate()
ax.set_xlim([datetime.date(2014, 1, 26), datetime.date(2014, 2, 1)])
ax.set_ylim([0, 5])

I get:

And the axes limits match the dates that I specified.

With help from Paul H's solution, I was able to change the range of my time-based x-axis.

Here is a more general solution for other beginners.

import matplotlib.pyplot as plt
import datetime as dt

# Set X range. Using left and right variables makes it easy to change the range.
#
left = dt.date(2020, 3, 15)
right = dt.date(2020, 7, 15)

# Create scatter plot of Positive Cases
#
plt.scatter(
  x, y, c="blue", edgecolor="black", 
  linewidths=1, marker = "o", alpha = 0.8, label="Total Positive Tested"
)

# Format the date into months & days
plt.gca().xaxis.set_major_formatter(mdates.DateFormatter('%m-%d')) 

# Change the tick interval
plt.gca().xaxis.set_major_locator(mdates.DayLocator(interval=30)) 

# Puts x-axis labels on an angle
plt.gca().xaxis.set_tick_params(rotation = 30)  

# Changes x-axis range
plt.gca().set_xbound(left, right)

plt.show()