Technical solutions are described for reusing a solution for a test. An example method includes building, by a processor, a solution cache including a tree structure representative of a plurality of solutions, which stores a key configurable immediate value of a previous solution as a node, the previous solution as a leaf node of the tree, and an edge from the node indicative of a value of the key configurable immediate value at the node. The method includes traversing nodes of the tree structure in the solution cache to identify key configurable immediate values of a previous solution identical to configurable immediate values from the test by identifying edges associated values identical to those from the test. In response to reaching a leaf node of the tree structure, using the solution(s) at the leaf node as a solution of the test.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A computer implemented method for reusing a solution for a test, the method comprising: building, by a processor, a solution cache comprising a tree structure representative of a plurality of solutions, the tree structure comprising a key configurable immediate value of a previous solution as a node, the previous solution as a leaf node of the tree, and an edge from the node indicative of a value of the key configurable immediate value at the node; in response to receiving the test for which a solution is to be determined: traversing to a first node of the tree structure in the solution cache, the first node comprising the key configurable immediate value of the previous solution identical to a configurable immediate value from the test; identifying an edge of the tree structure from the first node, the edge being associated with a value identical to a value of the configurable immediate value from the test; traversing to a next node of the tree structure along the edge; and in response to the next node being a leaf node of the tree structure, using the solution at the leaf node as a solution of the test. 2. The computer implemented method of claim 1, further comprising: in response to the next node of the tree structure not being a leaf node: identifying the key configurable immediate value of the previous solution represented by the next node; determining the presence of another configurable immediate value in the test, the other configurable immediate value identical to the key configurable immediate value at the next node; and in response to the other configurable immediate value being present, determining equality of a value of the other configurable immediate value in the test and a value associated with an edge from the next node; and in response to the values of the other configurable immediate value in the test and the key configurable immediate value at the next node being equal, traversing to a second next node along the edge from the next node. 3. The computer implemented method of claim 2, wherein in response to traversal of the tree structure not leading to a leaf node, determining a new solution for the test and updating the tree structure in the solution cache by adding key configurable immediate values of the new solution to the tree structure. 4. The computer implemented method of claim 1, wherein the configurable immediate value is a constant value in a constraint of the test, wherein the constant value is configurable. 5. The computer implemented method of claim 1, further comprising selecting the key configurable immediate value of the previous solution. 6. The computer implemented method of claim 5, wherein selecting the key configurable immediate value of the previous solution further comprises: traversing nodes of a constraint tree structure from a root node of the constraint tree structure, wherein the constraint tree structure comprises at least one of an operator node, an immediate value node, and a variable node; and in response to a traversed node being an immediate value node representative of a configurable immediate value, selecting the configurable immediate value as the key configurable immediate value. 7. The computer implemented method of claim 5, wherein selecting the key configurable immediate value of the previous solution further comprises: parsing a constraint string to identify operators, variables, and immediate values in the constraint string; and building a constraint tree structure corresponding to the constraint string, the constraint tree structure comprises at least one of an operator node, an immediate value node, and a variable node. 8. A system for reusing a solution of a constraint satisfaction problem as a solution for a test, the system comprising: a memory configured to store a solution cache, wherein the solution cache comprises a tree structure representative of a plurality of solutions, the tree structure comprising intermediate nodes and leaf nodes, each intermediate node corresponding to a key configurable immediate value of a previous solution, and each leaf node corresponding respective previous solutions, and an edge from the intermediate node indicative of a value of the key configurable immediate value at the intermediate node; a processor identifying, from the previous solutions in the solution cache, a solution to be reused for the test, the processor being configured to: determine configurable immediate values in the test; traverse to a first intermediate node of the tree structure in the solution cache, the key configurable immediate value of the previous solution at the first intermediate node identical to a first configurable immediate value from the test; identify an edge of the tree structure from the first intermediate node, the edge being associated with a value identical to a value of the first configurable immediate value from the configurable immediate values in the test; traverse to a next node of the tree structure along the edge; and in response to the next node being a leaf node of the tree structure, reuse the previous solution at the leaf node as a solution of the test. 9. The system of claim 8, wherein the processor is further configured to: in response to the next node of the tree structure being a second intermediate node: identify the key configurable immediate value of the previous solution represented by the second intermediate node; determine the presence of a second key configurable immediate value in the test, the second configurable immediate value being identical to the second key configurable immediate value; and in response to the second configurable immediate value being present, and a value of the second configurable immediate value in the test being equal to a value associated with an edge from the second intermediate node, traverse to a third node along the edge from the second intermediate node. 10. The system of claim 8, wherein the processor is further configured to: in response to traversal of the tree structure not leading to a leaf node of the tree structure: determine a new solution for the test; and update the tree structure in the solution cache based on the key configurable immediate values of the new solution. 11. The system of claim 8, wherein the configurable immediate value is a configurable constant value in a constraint of the test. 12. The system of claim 8, wherein the processor is further configured to select the key configurable immediate value of each respective previous solution in the solution cache. 13. The system of claim 12, wherein selection of the key configurable immediate value of a previous solution further comprises: traversal of nodes of a constraint tree structure from a root node of the constraint tree structure, wherein the constraint tree structure comprises at least one of an operator node, an immediate value node, and a variable node; and in response to a traversed node being an immediate value node representative of a configurable immediate value, selection of the configurable immediate value as the key configurable immediate value. 14. The system of claim 12, wherein selection of the key configurable immediate value of a previous solution further comprises: parsing of a constraint string to identify operators, variables, and immediate values in the constraint string; and generation of a constraint tree structure corresponding to the constraint string, the constraint tree structure comprises at least one of an operator node, an immediate value node, and a variable node. 15. A computer program product for reusing a solution from a solution cache, the computer product comprising computer readable storage medium, the computer readable storage medium comprising computer executable instructions, wherein the computer readable storage medium comprises instructions to: build a solution cache, wherein the solution cache comprises a tree structure representative of a plurality of solutions, the tree structure comprising intermediate nodes and leaf nodes, each intermediate node corresponding to a key configurable immediate value of a previous solution, and each leaf node corresponding respective previous solutions, and an edge from the intermediate node indicative of a value of the key configurable immediate value at the intermediate node; in response to receipt of a test for which a solution is to be determined: traverse to a first node of the tree structure in the solution cache, the key configurable immediate value of the previous solution at a first intermediate node identical to a first configurable immediate value from the test; identify an edge of the tree structure from the first intermediate node, the edge being associated with a value identical to a value of the first configurable immediate value from the test; traverse to a next node of the tree structure along the edge; and in response to the next node being a leaf node of the tree structure, reuse the previous solution at the leaf node as a solution of the test. 16. The computer program product of claim 15, wherein the computer readable storage medium further comprises instructions to: in response to the next node of the tree structure being a second intermediate node: identify the key configurable immediate value of the previous solution represented by the second intermediate node; determine the presence of a second configurable immediate value in the test, the second configurable immediate value being identical to the second key configurable immediate value; and in response to the second configurable immediate value being present, and a value of the second configurable immediate value in the test being equal to a value associated with an edge from the second intermediate node, traverse to a third node along the edge from the second intermediate node. 17. The computer program product of claim 15, wherein the computer readable storage medium further comprises instructions to: in response to traversal of the tree structure not leading to a leaf node of the tree structure: determine a new solution for the test; and update the tree structure in the solution cache based on the key configurable immediate values of the new solution. 18. The computer program product of claim 15, wherein the computer readable storage medium further comprises instructions to select the key configurable immediate value of each respective previous solution in the solution cache. 19. The computer program product of claim 18, wherein selection of the key configurable immediate value of a previous solution further comprises: traversal of nodes of a constraint tree structure from a root node of the constraint tree structure, wherein the constraint tree structure comprises at least one of an operator node, an immediate value node, and a variable node; and in response to a traversed node being an immediate value node, wherein the immediate value node is representative of a configurable immediate value, selection of the configurable immediate value as the key configurable immediate value. 20. The computer program product of claim 18, wherein selection of the key configurable immediate value of a previous solution further comprises: parsing of a constraint string to identify operators, variables, and immediate values in the constraint string; and generation of a constraint tree structure corresponding to the constraint string, the constraint tree structure comprises at least one of an operator node, an immediate value node, and a variable node.