| John A. Tester | |
| State: | Wisconsin |
| State Assembly: | Wisconsin |
| District: | Buffalo |
| Term Start: | January 1, 1883 |
| Term End: | January 5, 1885 |
| Predecessor: | Martin W. McDonnell |
| Successor: | Samuel Decius Hubbard |
| Party: | Republican |
| Birth Date: | 30 March 1835 |
| Birth Place: | Rongellen, Grisons, Switzerland |
| Death Place: | Seattle, Washington, U.S. |
| Restingplace: | Lake View Cemetery, Seattle |
| Spouse: | Mathilda F. Tester (died 1934) |
| Occupation: | Merchant |
| Allegiance: | United States |
| Branch: | United States Volunteers Union Army |
| Rank: | 1st Lieutenant, USV |
| Serviceyears: | 1861 - 1862 |
| Unit: | 6th Reg. Wis. Vol. Infantry |
| Battles: | American Civil War |
John A. Tester (March 30, 1835May 26, 1918) was a Swiss American immigrant, merchant, and Republican politician. He was a member of the Wisconsin State Assembly, representing Buffalo County in the 1883 session.[1]
Born in Rongellen, the Canton of Grisons, Switzerland, Tester moved with his parents to St. Louis, Missouri, in 1848 and then to Wisconsin in 1853. He served in the 6th Wisconsin Volunteer Infantry Regiment as first lieutenant during the American Civil War.[2] He served as deputy county treasurer for Buffalo County, Wisconsin, and on the Buffalo County Board of Supervisors. He also served on the Alma, Wisconsin, village board as trustee and as president.[3]