The son of a Scottish immigrant Tester came of age during the Great Depression. He found work in the mines of  Kirkland Lake, and developed pro-union sentiments. He was soon black-listed by the mining bosses and had to find work elsewhere.

He eventually moved to Oshawa where he was hired on with General Motors in the tool and die shop. He became a member of Local 222 of the United Autoworkers.

After the Second World War, Tester and his wife, Doris, moved to Sudbury where he found work as a machinist with Falconbridge.

He joined Local 598 of the Mine, Mill and Smelter Workers Union. It was one of the largest union locals in North America at the time and represented the huge workforces at Inco and Falconbridge.

Tester became a shop steward, serving on the bargaining committees in 1953, 1954, 1955 and 1959.

He was an eyewitness to some of the epic struggles of the Canadian labour movement including Local 598’s first strike at Inco in 1958, and the bitter strife between the Steelworkers and the Mine Millers.

After the Steelworkers took over representation of Inco workers, the once mighty Local 598 continued to represent Falconbridge workers. Tester was the president of Local 598 from 1969 to 1974.

Tester wrote a newspaper column from 1974 to 1993. He shared his considerable knowledge of union struggles and socialist causes with the readers of Northern Life.

A collection of those columns were published in a book, Son of a Working Man, shortly before his death in 1995 at the age of 81.