diff --git a/CMakePresets.json b/CMakePresets.json
index acfb2d7..b411f9b 100644
--- a/CMakePresets.json
+++ b/CMakePresets.json
@@ -16,23 +16,29 @@
       "name": "serial",
       "inherits": "base",
       "displayName": "Serial",
-      "description": "Default build, no OpenMP (was: make serial / make dyna)",
+      "description": "Simulation programs only, no OpenMP, no GoogleTest (was: make serial / make dyna)",
       "binaryDir": "${sourceDir}/build",
-      "cacheVariables": { "SLIMED_ENABLE_OPENMP": "OFF" }
+      "cacheVariables": {
+        "SLIMED_ENABLE_OPENMP": "OFF",
+        "SLIMED_BUILD_TESTS": "OFF"
+      }
     },
     {
       "name": "omp",
       "inherits": "base",
       "displayName": "OpenMP",
-      "description": "OpenMP build, -fopenmp and -DOMP (was: make omp / make dyna_omp)",
+      "description": "Simulation programs only, -fopenmp and -DOMP, no GoogleTest (was: make omp / make dyna_omp)",
       "binaryDir": "${sourceDir}/build-omp",
-      "cacheVariables": { "SLIMED_ENABLE_OPENMP": "ON" }
+      "cacheVariables": {
+        "SLIMED_ENABLE_OPENMP": "ON",
+        "SLIMED_BUILD_TESTS": "OFF"
+      }
     },
     {
       "name": "coverage",
       "inherits": "base",
       "displayName": "Coverage",
-      "description": "Serial build instrumented for gcov/lcov (was: make test COVERAGE=1)",
+      "description": "Instrumented for gcov/lcov; builds and runs the tests, so needs GoogleTest (was: make test COVERAGE=1)",
       "binaryDir": "${sourceDir}/build-cov",
       "cacheVariables": {
         "SLIMED_ENABLE_OPENMP": "OFF",
@@ -53,28 +59,24 @@
       "hidden": true,
       "output": { "outputOnFailure": true }
     },
-    { "name": "serial",   "inherits": "base", "configurePreset": "serial" },
-    { "name": "omp",      "inherits": "base", "configurePreset": "omp" },
     { "name": "coverage", "inherits": "base", "configurePreset": "coverage" }
   ],
 
   "workflowPresets": [
     {
       "name": "serial",
-      "displayName": "Configure, build and test the serial version",
+      "displayName": "Configure and build the serial version",
       "steps": [
         { "type": "configure", "name": "serial" },
-        { "type": "build",     "name": "serial" },
-        { "type": "test",      "name": "serial" }
+        { "type": "build",     "name": "serial" }
       ]
     },
     {
       "name": "omp",
-      "displayName": "Configure, build and test the OpenMP version",
+      "displayName": "Configure and build the OpenMP version",
       "steps": [
         { "type": "configure", "name": "omp" },
-        { "type": "build",     "name": "omp" },
-        { "type": "test",      "name": "omp" }
+        { "type": "build",     "name": "omp" }
       ]
     },
     {
diff --git a/README.md b/README.md
index d0e9fbd..8a4b8ea 100644
--- a/README.md
+++ b/README.md
@@ -115,13 +115,17 @@ SLIMED builds with CMake.
 Because serial and OpenMP builds are both used routinely, `CMakePresets.json`
 defines them as named presets, each with its own build directory:
 
-| Preset | Build directory | Equivalent to |
-| --- | --- | --- |
-| `serial` | `build/` | `make serial` / `make dyna` |
-| `omp` | `build-omp/` | `make omp` / `make dyna_omp` |
-| `coverage` | `build-cov/` | `make test COVERAGE=1` |
+| Preset | Build directory | Builds | Equivalent to |
+| --- | --- | --- | --- |
+| `serial` | `build/` | simulation programs | `make serial` / `make dyna` |
+| `omp` | `build-omp/` | simulation programs | `make omp` / `make dyna_omp` |
+| `coverage` | `build-cov/` | programs + unit tests | `make test COVERAGE=1` |
+
+`serial` and `omp` build the four simulation programs only. They set
+`SLIMED_BUILD_TESTS=OFF`, so GoogleTest is never looked for and does not need to
+be installed to use them.
 
-Configure, build and test in one command:
+Configure and build in one command:
 
 ```console
 cmake --workflow --preset omp
@@ -133,7 +137,16 @@ Or drive the steps separately:
 ```console
 cmake --preset omp           # configure
 cmake --build --preset omp   # build (all cores)
-ctest --preset omp           # test
+```
+
+To run the unit tests, either use the `coverage` preset or configure a build
+directory by hand -- `SLIMED_BUILD_TESTS` defaults to `ON`, so a plain
+configure includes them:
+
+```console
+cmake -S . -B build-test
+cmake --build build-test -j8
+ctest --test-dir build-test --output-on-failure
 ```
 
 Because each preset owns a separate build directory, switching back and forth
@@ -276,17 +289,26 @@ libstdc++; use the default Apple Clang when you need the tests.
 
 ### Tests
 
+`SLIMED_BUILD_TESTS` defaults to `ON`, so any build directory configured by hand
+includes the unit tests:
+
 ```console
-ctest --test-dir build --output-on-failure
+cmake -S . -B build-test
+cmake --build build-test -j8
+ctest --test-dir build-test --output-on-failure
 ```
 
+Note that the `serial` and `omp` presets deliberately set it to `OFF`, so
+`build/` and `build-omp/` contain no tests; use a separate directory as above,
+or the `coverage` preset.
+
 Each GoogleTest case is registered with CTest individually. Several tests open
 fixture files by paths relative to the working directory, so CTest runs
 `test_main` from the top of the source tree automatically. The binary can also
 be run directly, from the source root:
 
 ```console
-./build/bin/test_main
+./build-test/bin/test_main
 ```
 
 If GoogleTest is not installed, CMake prints a warning and skips the test
@@ -311,7 +333,7 @@ collect. There is no packaged `coverage-html` target yet.
 ```console
 cmake --build build --target clean   # like "make clean"; keeps the configuration
 rm -rf build                         # full reset, forgets all cached options
-rm -rf build build-omp build-cov     # remove every preset build directory
+rm -rf build build-omp build-cov build-test   # remove all build directories
 ```
 
 ### The previous Makefile