The Soviet Union's political courting of West Germany became more than a mere mischievous flirtation last week with the disclosure that Soviet President Leonid Brezhnev has invited Chancellor Helmut Schmidt to visit Moscow this summer.

Moscow's wooing takes on the appearance of a serious effort to test West Germany's bonds to the Western alliance and is sure to heighten concern in Washington about the faithfulness of America's mightist ally in Europe.

If Schmidt accepts -- and he is known to want to -- he will be the first major Western leader to see Brezhnew since the Soviet invasion of Afghanistan and could deliver a clear, foreceful message from the Atlantic Alliance. But the spectacle of Schmidt conferring with Brezhnev at this time involves political risks for Schmidt, both within the Western alliance, and at home although it is likely to have a favorable impact on his campaign for reelection this fall.

Opinion is divided on how Bonn has reacted to Moscow's overtures. Some U.S. analysts credit it with being realistic about Soviet advances, neither seeking nor expecting major shifts in Soviet policy towards the West. Others voice concern at what they regard as Bonn's tendency to be overly solicitous of the Soviets.

Twice since the December invasion, Schmidt has told parliamnent he was prepared to go to Moscow. He is expected to delay a deciion on Brezhnev's offer, which the Bonn government has publicized, while he consults his allies.

For Bonn, the trip is a must if West Germany wishes to preserve its many ties with Eastern Europe which were carefully constructed during the past decade by Schmidt's Social Democratic Party.

But the visit would enable the Soviets to tug further at already strained policy differences between Bonn and Washington. Moreover, the Soviets could use the chancellor's visit to temper the impact of the near certainty that Bonn will boycott the Moscow Olympics.

Beyond these immediate aims, the invitation appears to be part of a larger Soviet strategy to cultivate closer ties with Bonn.

Having peppered West Germany with neo-Nazi and warmongering epithets for most of the postwar period, Moscow several years ago began to assess its developing ties with Bonn to more positive terms.

This more pleasant tone was formalized by Brezhnev's 1978 visit to Bonn. During the visit, long-term economic cooperation agreements were signed.

Since then, the Kremlin has approved better transportation and economic links between West and East Germany. The flow of ethnic German refugees from Eastern Europe also continues with Moscow's blessings.

At the last Brezhnev-Schmidt meeting the invitation for the chancellor to visit Moscow was first tendered and was planned for this year. But the Afghanistan invasion and the resulting cooling of relations between the Soviet Union and the West put the visit in doubt.

Moscow appeared also to be angered by Bonn's leading role in December's NATO decision to station medium-range nuclear missiles in Europe.

The fact that Brezhnev has now unexpectedly offered a specific date for the visit this soon is being taken here both as a sign of Soviet interest in drawing Bonn out as well as evidence of Schmidt's success in striking a somewhat independent foreign policy from Washington.

Specialists here say Moscow has no illusions about pulling Bonn away from the Western alliance, but appears fascinated by the extent of recent German criticism of the United States and is eager to test the U.S.-West German relationship.

In addition, the Soviets may be motivated in part by defensive considerations. Analysts suggest that Moscow may be trying to ensure West Germany's position as a stabilizing force in Central Europe and in the context of East-West relations generally.

Schmidt continues to say he does not want to mediate between the Soviet Union and the United States. But in a speech last weekend, he decried the lack of communication between Moscow and Washington.

Without U.S. sanction, a Schmidt-Brezhnev summit will be open to attack by the opposition Christian Democrats. So far, no official public word has come from Washington.

Part of Washington's hesitation could well be the result of anxious stirring over what the West German chancellor is likely to say and do in Moscow. Having made no secret of his view that the United States has mismanaged its relations with the Soviet Union, Schmidt has shown himself ready to try a few maneuvers of his own.